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Volume 93-B, Issue SUPP_III July 2011

Abdel-Rahman Lawendy David W. Sanders Aurelia Bihari Amit Badhwar

Purpose: Compartment syndrome is a limb-threatening complication of skeletal trauma. Both ischemia and inflammation may be responsible for tissue necrosis in compartment syndrome (CS). In this study, normal rodents were compared with neutropenic animals to determine the importance of inflammation as a mechanism of cellular damage using techniques of intravital videomicroscopy (IVVM) and histochemical staining.

Method: Forty Wistar rats were randomised. Twenty animals served as a control (group C). Twenty rats were rendered neutropenic using cyclophosphamide (250mg/kg) (group N). Animals were anaesthetised with 5 % isoflurane. Elevated intracompartmental pressure was induced by saline infusion into the anterior hindlimb compartment and maintained at 30–40 mmHg for 0, 15, 45 or 90 minute time intervals. Following fasciotomy, the EDL muscle was analyzed using IVVM to quantify tissue injury, capillary perfusion, and inflammatory response.

Results: The proportion of injured cells decreased in group N compared to group C at all time intervals of EICP (p< 0.05). The proportion of injured cells in group N was 8 % after 0 minutes EICP, and 12, 15, and 10 % at 15, 45, and 90 min of EICP. In group C injured cells increased from 8 % to 20, 22, and 21 % at 15, 45, and 90 minutes EICP respectively. Groups N and C both demonstrated a time-dependent reduction in capillary perfusion. In group N continuously-perfused capillaries decreased from 79±4/mm with 0 min of EICP, to 48±11/mm (15min), 36±7/mm (45min), and 24±10/mm (90min) (p < 0.05). Overall, There was no difference between groups N and C with regards to perfusion (p> 0.05).

Conclusion: This study demonstrates the importance of inflammation as a cause of injury in compartment syndrome. There was a 50% decrease in injury in neutropenic animals compared to controls after 90 minutes of elevated intracompartmental pressure. Microvascular perfusion analysis demonstrated a time-dependent decrease in capillary perfusion in both neutropenic and control animals. Blocking of the inflammatory response via neutropenia was protective against tissue injury. These results provide evidence toward a potential therapeutic benefit for anti-inflammatory treatment of elevated intra-compartmental pressure.

Charles Secretan Jenn Bater Keith Bagnall Nadr M. Jomha

Purpose: The introduction of supplementary cells into a region of diseased or damaged tissue is becoming a viable treatment strategy in many areas of medicine. Mesenchymal stem cells (MSCs) are attractive for this purpose because they represent an autologous, multipotent cell source. However, it has been recognized that populations of MSCs represent a heterogenous group of cells with each cell subpopulation possessing unique terminal differential capacity. The CD44 cell surface receptor has previously been identified on some of the cells within the MSC population. It is also present on chondrocytes and is thought to play a critical role in cartilage matrix generation and homeostasis. We hypothesized that a CD44+ purified subpopulation of MSCs will possess enhanced chondrogenic potential and be more suitable for articular cartilage regeneration.

Method: Bone marrow aspirates were collected from orthopaedic patients undergoing iliac crest bone grafting. Human MSCs were isolated and cultured using standard techniques. Flow cytometry was utilized to identify the cell surface antigens characteristic of the MSC population. FACS was utilized to isolate the CD44 positive cells based on antigenic recognition, generating a CD44 positive population and a CD44 negative population. To confirm the multilineage potential of the isolates, defined media and culture conditions were utilized to differentiate both groups into osteocytes, adipocytes and chondrocytes. Real time polymerase chain reaction was utilized to quantify and compare the essential markers, collagen II, collagen I and aggrecan, in the stem cell derived chondrocytes. The CD44 enriched and CD44 depleted populations were compared.

Results: The cells isolated possessed a cell morphology and surface antigen profile consistent with a MSC population. In addition, both experimental groups demonstrated multipotent ability. Real time PCR analysis of the chondrogenic cells demonstrated that the CD44 positive population expressed collagen II and aggrecan at a significantly higher level than the CD44 negative population.

Conclusion: To date no group has successfully identified a relationship between a MSC subpopulation and the multipotent progenitors responsible for generating cartilage. This work demonstrated that there are MSC sub-populations with different potential for chondrogenic expression and represents an important step towards identifying MSC subpopulations with enhanced cartilage formation potential.

Frédérick-Charles Cloutier Dominique Rouleau Eric Beaumont Michael Atlan Pierre H. Beaumont

Purpose: Nerve re-generation and functional recovery are often incomplete after a peripheral nerve lesion. The aim of this study was to determine if the injection of chondrotinase ABC at the lesion site, one hour of electrical stimulation, and the combination of these treatments at the time of repair are effective in promoting nerve regeneration and muscle re-innervation.

Method: A complete right sciatic nerve section was done on 32 female Sprague-Dawley rats. End-to-end microsuture repair was performed and fibrin glue was added. Five groups were studied:

Sutures and Fibrine glue (S+F),

S+F and chondrotinase ABC,

S+F and electrical stimulation,

S+F and chondrotinase and electrical stimulation,

uninjured nerve. Video kynematic, EMG, muscle strengh and axonal count were used to asses nerve recovery at 150 days post-repair.

Results: Side video kinematics was performed and a larger excursion of the hip-ankle-toe angle during walking was showed in groups 2, 3, and 4. (p< 0.05) At 150 days, in-vivo EMg activity and maximal muscle force were similar in group 2, 3, 4, 5 and all of them were higher compared to group 1 (p< 0.05). Histological study revealed equivalent number of axone in all group and pore correlation with nerve function.

Conclusion: In conclusion, five months after nerve transection, the recovery is incomplete when using suture and fibrine glue only. Moreover, an injection of chondrotinase ABC at the lesion site and/or one hour of electrical stimulation of the proximal nerve stump is beneficial in promoting nerve regeneration and functional muscle re-innervation.

Michael Monument David A. Hart A. D. Befus Paul T. Salo Kevin Hildebrand

Purpose: To determine if mast cell activity is vital to the induction of joint capsule fibrosis and contracture formation in a rabbit model of posttraumatic joint contracture.

Method: To reproducibly induce joint contractures, we used a model of surgical injury and immobilization of the knee in skeletally mature New Zealand white rabbits. Four animals groups were studied: a non-operative control group (CON), an operative contracture group (ORC) and two-operative groups treated with a mast cell stabilizer, Ketotifen fumarate at doses of 0.5mg/kg (KF0.5) and 1.0mg/kg (KF1.0) twice daily subcutaneously, respectively. Animals were sacrificed after 8 weeks of immobilization. Flexion contractures (biomechanics), cellular counts of myofibroblasts and mast cells within the joint capsule (immunohistochemistry) and the joint capsule protein expression of TGF-β1, collagen I and III were quantified (western blots). Biomechanical data was interpreted using a linear regression analysis of repeated measures and an ANOVA analysis of variance was used for molecular data. Significance was defined at p< 0.05 for all statistical tests.

Results: Flexion contractures were most severe in the ORC group and treatment with Ketotifen (both KF0.5 and KF1.0) significantly reduced contracture severity by 52% and 42%, respectively (p< 0.03). Joint capsule myofibroblast and mast cell hyperplasia was a prominent feature of the more severely contracted ORC group and myofibroblast and mast cell numbers were dramatically reduced in both Ketotifen groups (p< 0.001). The expression of TGF-β1 and collagen I was also increased in the ORC group and significantly reduced in both Ketotifen groups (p< 0.01).

Conclusion: Joint capsule fibrosis, characterized by hyperplasia of myofibroblasts and mast cells and enhanced collagen deposition, is a prominent feature of posttraumatic joint contractures in this animal model. Treatment with a mast cell stabilizer reduced the molecular markers of joint capsule fibrosis and the resultant biomechanical severity of contracture formation. These results suggest mast cell activity may be an important process in the development of posttraumatic contractures and future work is needed to determine if pharmacological inhibition of mast cell activity has a preventative or therapeutic role in humans.

Greg W. McGarr David W. Sanders Amit Badhwar

Purpose: Compartment syndrome is a severe complication of skeletal trauma. Intravital microscopy (IVVM) has demonstrated an inflammatory response to compartment syndrome (CS). The molecular mechanisms underlying this inflammatory response are unknown. The purpose of this study was threefold. First, a broad inflammatory cytokine profile was examined to determine the molecules responsible for white cell recruitment. As well, skeletal muscle expression of white cell adhesion molecules including P-Selectin, E-Selectin, Mac-1 and ICAM-1 were examined to assess the extent of white cell activation in target tissues. Finally, skeletal muscle apoptosis was measured to determine the magnitude of cell death.

Method: Normal and neutropenic rats were randomised to either compartment syndrome or control groups. CS Animals were treated with 45 minutes of elevated intra-compartmental pressure (EICP) of the hindlimb. Fasciotomy was then performed, followed by 60 minutes of reperfusion. Control animals experienced no EICP. Blood was collected from carotid arterial lines used for pressure monitoring. Skeletal muscle tissue samples were collected from the EDL following reperfusion. Blood samples were obtained from carotid arterial lines and skeletal muscle was collected following reperfusion. A Multiplex assay was used to examine serum levels of 24 proinflammatory cytokines/chemokines. Skeletal muscle mRNA levels of P-Selectin, E-Selectin, Mac-1 and ICAM-1 were evaluated using real-time PCR. Finally, skeletal muscle apoptosis was measured by DNA laddering and a caspase-3 assay.

Results: Neutropenic CS animals demonstrated a continuous increase in TNF-alpha levels, peaking at 700+/−350pg/ml by 60 minutes of reperfusion. TNF-alpha values for other groups did not increase. A 104-fold increase in ICAM-1 mRNA levels was observed in neutropenic CS rats while other groups showed no significant increase. There was no significant increase in any group for P-Selectin, E-Selectin, or Mac-1.

Conclusion: This study is the first to attempt to describe the molecular inflammatory response in CS. Neutropenic CS animals demonstrated an upregulation in TNF-alpha and ICAM-1 mRNA levels. This likely represents an attempt to generate an inflammatory response in the neutropenic animals. Additional data at incremental timepoints is necessary to further characterize the molecular mechanisms. However, both TNF-alpha and ICAM-1 appear to be important in the mechanism of inflammatory activation in compartment syndrome.

Andrei R. Manolescu David Cinats Charles Secretan Deborah O’Neill Chris Cheeseman Keith Bagnall Nadr M. Jomha

Purpose: Differentiation of BM-MSCs into adult chondrocytes represents a complex physiological mechanism and full characterization of each individual stage through which the BM-MSC differentiate into adult chondrocytes is not yet understood. The physiological micro-environment of the chondrocytes is intensely hypoxic which triggers over-expression SLC2A proteins (GLUTs) in their membranes as a compensatory mechanism for energy production within the glycolytic cycle.

Method: We cultured and differentiated BM-MSC, and adult chondrocytes in hypoxic (5% O2 tension) and normoxic (20% O2) conditions. Within this cell populations we screened for the presence of the 12 GLUT genes as well as quantification of the variation of the 12 GLUTs gene translation by simple pcr and rt-pcr. The expression profile of the GLUT proteins was investigated using western blot analysis and immunohistochemistry. Functional characterization of the GLUTs expressed in the different cell populations was carried out by the means of radio-isotope labeled hexose fluxes done accordingly to the substrate specificity and kinetic properties particular to each SLC2A isoforms.

Results: Our data showed that the functional genotype and phenotype of the adult chondrocyte and hypoxic BM-MSC comprised an extensive expression of fructose-transporting GLUTs as opposed to the glucose-only transporting isoforms expression in normoxic BM-MSC. The flux data showed clear similarities in functional GLUT profiles between BM-MSC cultured in hypoxic conditions, adult chondrocytes. Investigation of the uptake of a panel of five individual sugars (glucose, fructose, 2-deoxy-gluose, 3-orthomethyl-glucose and galactose) in these cellular populations under both hypoxic and normoxic conditions and in the presence and absence of Cytochalasin B (a GLUT1-specific inhibitor) showed that SLC2A class II transporters (GLUTs 5, 7, 9 and 11) play a more important role in the uptake of sugars by the normal hypoxic chondrocytes when compared to the ubiquitously-expressed GLUT1.

Conclusion: Use of this approach allows the correct culturing conditions to be identified that would select for those chondrocyte precursors from the total BM-MSC population that would have the best potential for producing viable articular cartilage. In addition, specific substrates for GLUTs isoforms could be used for physiologic, non-invasive and real time imaging of cartilage, BM-MSC and cartilage autograft by means of Positron Emission Tomography.

Fackson Mwale Hong Tian Wang Pierre-Luc Girard-Lauriault Michael R. Wertheimer John Antoniou Alain Petit

Purpose: Recent evidence indicates that a major drawback of current cartilage and intervertebral disc (IVD) tissue engineering is that human mesenchymal stem cells (MSCs) from osteoarthritic patients rapidly express type X collagen (COL10A1), a marker of late-stage chondrocyte hypertrophy associated with endochondral ossification. We recently discovered that a novel atmospheric-pressure plasma-polymerized thin film substrate, named “nitrogen-rich plasma-polymerized ethylene” (PPE:N), is able to inhibit COL10A1 expression in committed MSCs. However, the cellular mechanisms implicated in the inhibition of COL10A1 expression by PPE:N surfaces are unknown.

Method: Human mesenchymal stem cells (MSCs) were obtained from aspirates from the intramedullary canal of donors (60–80 years of age) undergoing total hip replacement for osteoarthritis. Bone marrow aspirates were processed and MSCs were cultured on commercial polystyrene (PS control) and on PPE:N surfaces in the presence of different kinases and cyclooxygenase inhibitors for 3 days. Total RNA was extracted with TRIzol reagent (Invitrogen, Burlington, ON) and the expression of COL10A1, cyclooxygenase-1 (COX-1), and 5-lipoxygenase (5-LOX) genes was measured by real-time quantitative RT-PCR.

Results: Results showed that a non-specific inhibitor of cyclooxygenases reduced the expression of COL10A1. In contrast, inhibitors of protein kinases stimulated the expression of COL10A1. Furthermore, potent and selective inhibitors of COX-1 and 5-LOX also reduced the expression of COL10A1. However, COX-2 and 12-LOX inhibitors had no significant effect on the expression of COL10A1. COX-1 gene expression was also decreased when MSCs were incubated on “S5” PPE:N surfaces. Interestingly, MSCs did not express 5-LOX.

Conclusion: PPE:N surfaces suppress COL10A1 expression through the inhibition of COX-1 which is directly implicated in the synthesis of prostaglandins. The decreased expression of COX-1 and COL10A1 in human MSCs cultured on PPE:N is therefore in agreement with the induction of the osteogenic capacity of rat bone marrow and bone formation by systemic or local injection of PGE2 in rats. However, PGE2 and other prostaglandins inhibited COL10A1 expression in chick growth plate chondrocytes. This suggests that the effect of prostaglandins on COL10A1 expression may be cell-specific or may be dependent on pre-existing patho-physiological conditions.

Richard C. Smith Brenton Short Paul W. Clarkson Bassam A. Masri Michael Underhill

Purpose: Chondral injuries of the knee are commonly seen at arthroscopy, yet there is no consensus on the most appropriate treatment method. However, untreated cartilage injury predisposes to osteoarthritis contributing to pain and disability. For cell-based cartilage repair strategies, an ex-vivo expansion phase is required to obtain sufficient numbers of cells needed for therapy. Although recent reports demonstrated the central role of oxygen for the function and differentiation of chondrocytes, little is known of the effect of physiological low oxygen concentrations during the expansion of the cells and whether this alters their chondrogenic capacity.

Method: Initial studies of chondrocyte expansion were performed in mature mice, with cells expanded at either atmospheric oxygen tension (21%) or 5% 02 in monolayer cultures. Chondrogenic differentiation was subsequently assessed via micromass culture. Having determined that oxygen tension influences murine chondrocyte expansion and differentiation, similar studies were conducted using adult human chondrocytes taken from knee arthroplasty off-cuts, with mRNA expression of select genes involved in the chondrogenic program analyzed by q-PCR.

Results: Cellular morphology was improved in hypoxic culture, with a markedly more fibroblastic appearance seen after greater than 2 passages in 21% O2. Micromass cultures maintained in hypoxic conditions demonstrated stronger staining with Alcian blue, indicating stronger expression of cartilaginous glycosaminoglycans. Collagen type II mRNA expression was two-fold higher in cells expanded at 5% as compared to expansion at 21% O2. Micromass cultures grown at 21% O2 showed up to a twofold increase in the tissue content of glycosaminoglycans when formed with cells expanded at 5% instead of 21% O2. However, no differences in the mRNA expression or staining for collagen type II protein were observed in these micromass cultures. Hypoxia (5% O2) applied during micromass cultures gave rise to tissues with low contents of glycosaminoglycans.

Conclusion: In-vivo, chondrocytes are adapted to a hypoxic environment. Taking this into account, applying 5% O2 in the expansion phase in the course of cell-based cartilage repair strategies, may result in a repair tissue with higher quality by increasing the content of glycosaminoglycans.

Krishna Maragh Jenn Bater Charles Secretan Keith M. Bagnall Nadr M. Jomha

Purpose: Current techniques for articular cartilage repair remain suboptimal. The best technique involves the introduction of cultured chondrocytes into the injury site. Experimental results of current chondrocyte culture and expansion techniques (passaging) have shown phenotypic alteration resulting in fibroblast-like cells. Therefore, treatment methods that propose the transplantation of cultured chondrocytes might be transplanting fibroblast-like cells instead of chondrocytes. This experiment explored the difference in genetic expression of chondrocytes left at confluence compared to chondrocytes that were passaged as performed in current culture techniques. It was hypothesized that chondrocytes left at confluence would maintain their collagen I and collagen II gene expression over time.

Method: Fresh normal human articular cartilage was collected from deceased donor patients. The matrix was digested and the chondrocytes were plated in monolayer to create two groups. The first group was cultured and passaged 2? at confluence seven times. The second group was cultured at confluence and left for seven weeks, with medium changes every 3–4 days without passaging. At weekly intervals RNA was extracted from cells in both groups and analyzed with real time PCR, probing specifically for the genes responsible for the production of collagen I, collagen II, aggrecan, and GAPDH. This was done in duplicate.

Results: Collagen II gene expression was maintained over seven weeks in cells left at confluence but was decreased in passaged cells. Collagen I gene expression decreased over seven weeks in cells left at confluence, but remained the same in passaged cells. Aggrecan gene expression remained the same in both groups.

Conclusion: Current culture and expansion techniques that employ passaging (as used in clinical scenarios) result in significant alterations in gene expression that are inconsistent with the current definition of a “chondrocyte”. Culturing chondrocytes at confluence can produce gene expression more similar to native chondrocytes but even these cells have expression of collagen type I that should not be present in chondrocytes. The results of this study suggest that further investigation is required to develop chondrocyte culture and expansion techniques that minimize the de-differentiation of chondrocytes by maintaining collagen II gene expression and eliminating/preventing collagen I gene expression.

Neil Saran Robert É. Turcotte Renwen Zhang

Purpose: Extracortical bone bridging and ingrowth have been shown to reduce stresses on the stem and cement mantle of tumor endoprostheses. The purpose of this study was to assess the effect of bone morphogenetic protein 7 (BMP-7) delivered by Peri-Apatiteâ (PA, Stryker Orthopaedics) hydroxyapatite coating on porous segmental replacement prostheses.

Method: Eighteen mature mongrel canines were implanted with unilateral segmental replacement prostheses made of a cobalt-chromium (Co-Cr) alloy and coated with two layers of sintered Co-Cr alloy beads (diameter 600 to 800mm). The control group consisted of a plain porous coated segmental prosthesis without any PA coating. Group 2 consisted of a PA-coated segmental prosthesis coated with buffer solution. Group three consisted of a PA-coated segmental prosthesis loaded with rhBMP-7 (Stryker Biotech) in a buffer solution carrier. Group 1 had the implant only. Group 2 had the buffer solution evenly applied to the porous coat and group 3 had 2.9 mg of BMP-7 in liquid buffer solution evenly applied. The canines were allowed to fully bear weight without restrictions. The femurs were retrieved at twelve weeks for radiographic and histologic analysis.

Results: Gross and radiographic data of the retrieved specimens showed that all six PA-coated implants augmented with BMP-7 had complete bone bridging; only one of the PA-coated implants and only two of the plain porous implants were completely bridged. There was a greater percentage of bone apposition for the BMP-7 augmented PA-coated group compared to both the plain (p=0.0026) and the PA-coated (p=0.0001). There was no difference in bone formation or bone apposition between the plain and PA-coated groups. Histology revealed greater depth of bone ingrowth in the BMP-7 augmented PA-coated group as compared to the plain (p< 0.0001) and the PA-coated (p< 0.0001) groups. There was also significantly greater bone apposition in the BMP-7 augmented PA coated groups as compared to the plain (p=0.0014) and PA-coated (p=0.0067) groups. There was no significant difference in depth of bone ingrowth or bone apposition between the plain and PA-coated groups.

Conclusion: BMP-7 when used to augment PA-coated prostheses in a canine segmental defect model can significantly improve extracortical bone bridging and bone ingrowth. PA-coated implants may be considered to deliver the exogenous biological growth factors.

Kivanc I. Atesok Ru Li Emil H. Schemitsch

Purpose: Endothelial Progenitor Cells (EPCs) have been proven to contribute to formation of new blood vessels. The objective of this study was to evaluate the effects of local EPC therapy on the stimulation of angiogenesis at a fracture site and the promotion of bone healing by increasing osteogenesis and callus formation.

Method: Rat bone marrow EPCs were isolated and cultured. A segmental bone defect (4mm.) was created in the rat femur diaphysis and stabilized with a mini-plate. A gelfoam piece impregnated with a solution of EPCs (1x106) was placed into the fracture gap. Control animals received only saline-gelfoam with no cells. In total, 42 rats were studied: 21 in EPC and 21 in control groups. Seven animals were sacrificed from each group at one, two, and three weeks post-operatively. Plain radiographs of the operated femur were taken before sacrifice. Operated femurs were harvested and the specimens from the osteotomy site were collected for histological evaluation. The x-rays were scored in a scale from zero to five according to the percentage and the intensity of the bone filling at the osteotomy site. Hematoxylin-eosin stained slides were evaluated for new vessel formation and the amount of bone tissue.

Results: Radiographically, at three weeks, the mean score for the EPC group was 4.5 with five out of seven animals having bridging callus; whereas for the control group, the mean score was 2.2 with no bridging callus formation. At two weeks, EPC treated animals had a mean score of 2.4, and the control group had a score of 1. Bone formation was insignificant at one week in either group, however, the scores tended to be higher in the EPC group animals than the control; 0.6 to 0.3 respectively. Histological evaluation revealed that the specimens from EPC treated animals had abundant spicules of trabecular bone containing predominantly bone cells, osteoid, and new vessels. Conversely, control animals had scarce trabecular bone with markedly less bone cells and vessels.

Conclusion: Local EPC therapy stimulates angiogenesis and increases osteogenesis and callus formation post fracture. Our report encourages further investigation of the local use of EPCs as a potential therapy to promote bone regeneration.

Paul R. T. Kuzyk Emil H. Schemitsch John E.D. Davies

Purpose: The aim of our study was to evaluate bone formation and angiogenesis produced within a biodegradable poly-D, L-lactide-co-glycolide acid/calcium phosphate (PLGA/CaP) scaffold when used to treat a diaphyseal tibia defect and compare this to an iliac crest autograft or an empty defect.

Method: An 8.0 mm diaphyseal defect was created in a canine tibia model. All tibiae were reamed to 7.0 mm and fixed with a 6.5 mm statically locked intramedullary nail. Eighteen canines were allotted into three treatment groups:

empty (N=5),

iliac crest autograft (N=6), or

PLGA/CaP biodegradable scaffold Tissue Regeneration Therapeutics Inc., ON, Canada) (N=7).

Fluorescent markers were given at different times: calcein green (six weeks), xylenol orange (nine weeks), and tetracycline (11 and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Radiography, Micro CT, and brightfield and fluorescent microscopy were used for analysis.

Results: Micro CT and brightfield images of scaffold samples displayed multiple vessels (10 to 100μm) within the scaffold. The bone volume and vasculature volume (measured with Micro CT) within the tibial defect site were reported as a percentage of the total volume of the defect site. The percent bone volume within the defect site was not different between treatment groups (p=0.112). There was greater percent vasculature volume in the scaffold group than the autograft group (p< 0.001). Bone formation at the osteotomy sites was defined as the distance from the original osteotomy site to the tip of newly formed bone. Osteotomy bone formation was significantly greater in the scaffold group than the autograft group (p=0.015). Osteotomy sites associated with greater angiogenesis displayed greater bone formation. Bone formation rates were reported as the distance between the fluorescent bone labels. Autograft samples had the greatest bone formation rates within the periosteum. Autograft and scaffold samples had the greatest rate of bone formation within the cortex.

Conclusion: Our canine tibial defect model provides a satisfactory facsimile of the traumatic tibia fracture with associated bone loss. The PLGA/CaP biodegradable scaffold we have employed promotes angiogenesis within a defect and could be used in conjunction with autografting.

Thomas Karakolis Gregory R. Wohl

Purpose: Bone fatigue damage can lead to stress fractures and may play a role in fragility fractures. The rat forelimb compression model has been used to examine biological responses and gene expression associated with woven bone repair after fatigue damage. Development a similar mouse model would enable the use of genetically modified mice to study molecular mechanisms associated with bone repair.

Method: Following approval from our Central Animal Facility, forelimbs of male retired breeder C57BL/6 mice and Sprague Dawley rats (n=31 each) were loaded in axial compression across the carpus and olecranon. First, both forelimbs (postmortem, n=6 each) were monotonically loaded to determine failure load. Next, both forelimbs of animals (postmortem, n=5 each) were loaded cyclically to sub-fracture load (67% of monotonic load for mice, 55% for rats) until fatigue failure. Following analysis of fatigue displacement histories, right forelimbs (post-mortem, n=10 each) were loaded cyclically to a set displacement short of the expected failure displacement (mice–30%; rats–55%). Non-loaded left forelimbs served as controls. Three-point bending tests were performed on the ulnae; mechanical properties were compared between fatigued and non-loaded limbs. Finally, right forelimbs (n=10 each) were cyclically loaded in anaesthetised (2.5% isofluorane) animals to 30% (mice) and 55% (rats) of failure displacement. Animals recovered for seven days; microCT imaging and three-point bend tests were performed on the ulnae.

Results: Ultimate forelimb failure loads were 5.63 ± 0.47 N (mouse) and 57.1 ± 5.8 N (rat). Measured from the 10th cycle, fatigue failure occurred at displacements of 1.68 ± 0.21 mm (mouse) and 2.96 ± 0.22 mm (rat). In three-point bending, fatigue damaged ulnae failed at significantly lower loads versus control (mouse −51.6%; rat −32.1%). After seven days healing, bone cross-sectional area was significantly greater (microCT) and mechanical properties partially recovered (−13.8% versus control).

Conclusion: Rat and mouse forelimb fatigue loading models have been developed to induce repeatable bone damage. Observed differences in fatigue behaviour necessitated different loading parameters between models. Following seven days of healing, recovery of mechanical strength accompanied woven bone formation (demonstrated by microCT). Further work will compare the biological, woven bone, response between the mouse and rat forelimb models.

Paul R. T. Kuzyk John E.D. Davies Emil H. Schemitsch

Purpose: The purpose of this study was to relate the extent of reaming to bone formation occurring around a critical sized defect in the tibia.

Method: Eleven canines were allocated into 2 groups: empty (N=5) or iliac crest autograft (N=6). All tibiae were reamed to 7.0 mm and fixed with a 6.5 mm statically locked intramedullary nail after creation of an 8.0 mm diaphyseal defect. The extent of reaming of the canal was dependent on the cross-sectional area of the tibia as all tibiae were reamed to 7.0 mm. Fluorescent markers were given at different times: calcein green (6 weeks), xylenol orange (9 weeks), and tetracycline (11 and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Radiography, Micro CT, brightfield microscopy and fluorescent microscopy were used for analysis.

Results: Bone and vasculature volume within the defect were reported as a percentage of the total volume of the defect. Linear regression analysis of percent bone volume (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.925 (p=0.025) for the empty group and 0.244 (p=0.641) for the autograft group. Linear regression analysis of percent vasculature volume (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.784 (p=0.117) for the empty group and −0.146 (p=0.783) for the autograft group. Bone formation at osteotomy sites was defined as the distance from the original osteotomy site to the tip of newly formed bone. Linear regression analysis of bone formation at the osteotomy sites (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.132 (p=0.832) for the empty group and −0.937 (p=0.006) for the autograft group. Bone formation rates were reported as the distance between the fluorescent labels. Bone formation rate was less within the endosteum, cortex and periosteum with extensive reaming in empty samples.

Conclusion: Our results suggest that the acute management of tibia fractures with bone defects should involve limited reaming. This does not apply when the defect is autografted. Limited reaming may be defined by the cross-sectional area of the tibia in ratio to that of the reamer.

John Street Brian Lenehan Charles G. Fisher Marcel Dvorak

Purpose: Apoptosis of osteoblasts and osteoclasts regulates bone homeostasis. Vertebral osteoporotic insufficiency fractures are characterised by pathological rates of osteoblast apoptosis. Skeletal injury in humans results in ‘angiogenic’ responses primarily mediated by vascular endothelial growth factor(VEGF), a protein essential for bone repair in animal models. Osteoblasts release VEGF in response to a number of stimuli and express receptors for VEGF in a differentiation dependent manner. This study investigates the putative role of VEGF in regulating the lifespan of primary human vertebral osteoblasts (PHVO) in-vitro.

Method: PHVO were cultured from biopsies taken at time of therapeutic vertebroplasty and were examined for VEGF receptors. Cultures were supplemented with VEGF(0–50ng/mL), a neutralising antibody to VEGF, mAB VEGF(0.3ug/mL) and Placental Growth Factor (PlGF), an Flt-1 receptor-specific VEGF ligand(0–100 ng/mL) to examine their effects on mineralised nodule assay, alkaline phosphatase assay and apoptosis. The role of the VEGF specific antiapoptotic gene target BCl2 in apoptosis was determined.

Results: PHVO expressed functional VEGF receptors. VEGF 10 and 25 ng/mL increased nodule formation 2.3- and 3.16-fold and alkaline phosphatase release 2.6 and 4.1-fold respectively while 0.3ug/mL of mAB VEGF resulted in approx 40% reductions in both. PlGF 50ng/mL had greater effects on alkaline phosphatase release (103% increase) than on nodule formation (57% increase). 10ng/mL of VEGF inhibited spontaneous and pathological apoptosis by 83.6% and 71% respectively, while PlGF had no significant effect. Pretreatment with mAB VEGF, in the absence of exogenous VEGF resulted in a significant increase in apoptosis (14 versus 3%). BCl2 transfection gave a 0.9% apoptotic rate. VEGF 10 ng/mL increased BCl2 expression four fold while mAB VEGF decreased it by over 50%.

Conclusion: VEGF is a potent regulator of osteoblast life-span in-vitro. This autocrine feedback regulates survival of these cells, mediated via the KDR receptor and expression of BCl2 antiapoptotic gene. This mechanism may represent a novel therapeutic model for the treatment of osteoporosis.

Marlis Sabo Steven I. Pollmann Kevin R. Gurr Christopher Bailey David W. Holdsworth

Purpose: Bone mineral density (BMD) is an important factor in the performance of orthopaedic instrumentation both in and ex-vivo, and until now, there has not existed a reliable technique for determining BMD at the precise location of such hardware. This paper describes such a technique using cadaveric human sacra as a model.

Method: Nine fresh-frozen sacra had solid and hollow titanium screw placed into the S1 pedicles from a posterior approach. High-resolution micro-computed tomography (CT) was performed on each specimen before and after screw placement. All images were reconstructed with an isotropic spatial resolution of 0.308 mm, reoriented, and the pre-screw and post-screw scans were registered and transformed using a six-degree rigid-body transformation matrix. Once registered, two points, corresponding to the center of the screw at the cortex and at the screw tip, were determined in each scan. These points were used to generate cylindrical regions of interest (ROI) with the same trajectory and dimensions as the screw. BMD measurements were obtained within each of the ROI in the pre-screw scan. To examine the effect of artefact on BMD measurements around the titanium screws, annular ROI of 1 mm thickness were created expanding from the surface of the screws, and BMD was measured within each in both the pre-and post-screw scans.

Results: The registration process was accurate, with an error of 0.2 mm. Four specimens were scanned five times with repositioning, and error in BMD measurements was ± 2%. BMD values in the cylindrical ROI corresponding to screw trajectories were not statistically different from side to side of each specimen (p = 0.23). Artefact-related differences in BMD values followed an exponential decay curve as distance from the screws increased, approaching a low value of approximately 20 mg HA/cc, but not disappearing completely.

Conclusion: CT in the presence of metal creates artefact, making measured BMD values near implants unreliable. This technique is accurate for determination of BMD, non-destructive, and eliminates the problem of this metal artefact through the use of co-registration of a pre- and post-screw scan. This technique has applications both in-vitro and in-vivo.

Claire Li Ru Li Michael D. McKee Emil H. Schemitsch

Purpose: Vascular Endothelial Growth Factor (VEGF) plays an important role in promoting angiogenesis and osteogenesis during fracture repair. Our previous studies have shown that cell-based VEGF gene therapy accelerates bone healing of a rabbit tibia segmental bone defect in-vivo, and increases osteoblast proliferation and mineralization in-vitro. The aim of this project was to examine the effect of exogenous human VEGF (hVEGF) on the endogenous rat VEGF messenger RNA (mRNA) expression in a cell-based gene transfer model.

Method: The osteoblasts were obtained from the rat periosteum. The fibroblasts were obtained from the rat dermal tissue. The cells were then cultured to reach 60% confluence and transfected with hVEGF using Superfect. Four groups were:



Osteoblasts alone, and

Fibroblasts only.

The cultured cells were harvested at 1, 3 and 7 days after the transfection. The total mRNA was extracted (TRIZOL); both hVEGF and rat VEGF mRNA were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantified by VisionWorksLS.

Results: The hVEGF mRNA was detected by RT-PCR from transfected osteoblasts after three days of gene transfection. The hVEGF mRNA expression in transfected fibroblasts increased exponentially at days 1, 3 and 7 after the transfection. We compared the endogenous rat VEGF mRNA expression level of the osteoblasts or fibroblasts that were transfected with hVEGF with the cells without the transfection. The hVEGF transfected osteoblasts had a greater rat VEGF mRNA expression than the non-transfected osteoblasts. Furthermore, when hVEGF was transfected to the rat fibroblasts, the endogenous mRNA expression level measured was also greater than that from the non-transfected fibroblasts. Rat VEGF mRNA expression increased in the first three days of the hVEGF transfection, but the expression level was reduced at Day 7.

Conclusion: These results suggest that cell-based hVEGF gene therapy enhances endogenous rat VEGF mRNA expression in both osteoblasts and fibroblasts.

Kyle A. R. Kemp Michael J. Dunbar Lori A. Livingston Allan Hennigar

Purpose: Despite their inclusion within clinical practice, standardized radiographs may not accurately project an individual’s level of function and mobility. The purpose of this study is to examine the potential relationship between established radiographic features and lurch; a functional measure of asymmetric gait, in a group of patients who will receive total hip arthroplasty (THA).

Method: Thirty-two patients (16 females, 16 males) identified as hip replacement candidates were recruited, with a mean age of 57.0 years. Lurch was obtained using the Walkabout Portable Gait Monitor (WPGM); a wireless, triaxial accelerometry device. The independent variables were comprised of the Kellgren-Lawrence Scale, and a collection of standard radiographic features, as adopted by the American Academy of Orthopaedic Surgeons (AAOS), the National Institutes of Health (NIH), and the World Health Organization (WHO). Radiographs were blinded, and the surgeon completing the rating scale was unaware of patient’s lurch values. Age-adjusted regression analyses were used to examine the potential association between each radiographic feature and lurch.

Results: Increased amounts of lurch (i.e. functional impairment) were independently associated with higher Kellgren-Lawrence Scale scores (p=.047), increased Joint Space Narrowing in the mid-portion of the joint (zone 2; p=.004), the presence of acetabular wear (p=.045), an increased severity of subchondral femoral head cysts (p=.004), and higher surgeon-rated Visual Analog Scale scores for overall severity of joint degeneration (p=.008). Lurch was not significantly associated with the remaining 10 features which were examined. Further analyses revealed that lurch was not significantly associated with certain demographic factors, including sex, Body Mass Index, and co-morbid health conditions.

Conclusion: Although the Kellgren-Lawrence scale was associated with an objective measure of gait, our results indicate that other radiographic features may provide a more accurate prediction of gait performance among this patient population. As lurch appears to be a robust objective measure of physical impairment, which is unaffected by BMI and co-morbidities, we believe that portable triaxial accelerometers can likely be used to conveniently collect objective gait data. This functional data may be used to supplement clinical efforts to screen and prioritize appropriate hip arthroplasty patients.

Louis M. Ferreira Graham J.W. King James A. Johnson

Results: Repeatability of creating motion-based JCS was less than 1 mm and 1° in all directions. The inter-specimen standard-deviations of position and orientation measurements were smaller for the motion-based than for the anatomy-based JCS in every direction and for every specimen (p< 0.006). The ulno-humeral varus angle and internal/external rotation kinematics of active flexion showed less inter-specimen variability when calculated using motion-based JCS (p< 0.05).

Petar Seslija Xunhua Yuan Douglas Naudie Terry M. Peters Robert B. Bourne Steven J.M. MacDonald David W. Holdsworth

Purpose: Accurate measurement of dynamic joint motion remains a clinical challenge. To address this problem, we have developed a low-dose clinical procedure using the Roentgen Single-plane Photogrammetric Analysis (RSPA) technique. A validation study was performed in a clinical setting, using a conventional digital flat-panel radiography system.

Method: To validate the technique, three experiments were performed: assessment of static accuracy, dynamic repeatability and measurement of effective dose. A knee joint phantom, imbedded with tantalum markers, was utilized for the experiments. Relative spatial positions of the markers were reconstructed using Radiostereometric Analysis (RSA). A digital flat-panel radiography system was used for image acquisition, and the three-dimensional pose of each segment was determined from single-plane projections by applying the RSPA technique. All images were processed using software developed in-house. To assess static accuracy, the phantom was mounted onto a three-axis translational stage and moved through a series of displacements ranging from 0 to 500 μm. Images of the phantom were acquired at each position. Accuracy was calculated by analyzing differences between reconstructed and applied displacements. To assess dynamic repeatability, the phantom was mounted on a six-axis robot, programmed to apply a flexion-extension movement to the joint. Multiple cine acquisitions of the moving phantom were acquired (30 fps, 4 ms exposure). Repeatability was calculated by analyzing the variation between motions reconstructed from repeated acquisitions. The effective dose of the procedure was measured using an ion-chamber dosimeter. The ion chamber was positioned between the phantom and x-ray source, facing the source. Entrance exposure was measured for multiple acquisitions, from which the effective dose was calculated.

Results: The accuracy determined from the static assessment was 25 μm and 450μm at the 95% confidence intervals for translations parallel and orthogonal to the image plane, respectively. Repeatability of the motion reconstructed from dynamic acquisitions was better than ± 200 μm for translations and ± 0.1 for rotations. The average effective dose for a 6 second dynamic acquisition was approximately 2μSv.

Conclusion: The proposed clinical procedure demonstrates both a high degree of accuracy and repeatability, and delivers a low effective dose.

Inder Gill Vinod Kolimarala Richard Montgomery

Purpose: To analyse the results of the use of Recombinant Bone Morphogenic Protein (BMP-7) for treatment of fracture nonunions at our institution.

Method: From 2001 to 2006, 23 patients with fracture non-union were treated with BMP-7 for bone healing. There were 14 male and nine females. The mean age of patients was 45 years (Range 21–76 yrs). There were 11 femoral, nine tibial and three humerus fractures. There were four open injuries. The average number of operations before BMP-7 insertion was 2.5 (Range 0–6). The mean time between the injury and BMP insertion was 52 months (Range 5–312). Nine (40%) patients had previous autologous bone graft inserted without union. 4 patients had BMP-7 insertion on its own. In another 4 patients it was mixed with allograft. In the rest of 15 patients BMP-7 was mixed with autologous bone graft. 2 patients needed BMP-7 insertion on 2 separate occasions. In all except 1 patient the original fixation of the fracture had to be revised using various appropriate methods.

Results: All the fracture went on to unite within an average of seven months (Range 4–16). There were no complications from the use of BMP-7.

Conclusion: Use of recombinant BMP-7, bone graft and stable fixation lead to fracture union in all our patients. We believe that the use of BMP-7 improved the chances of fracture healing in persistent non-unions and it is safe and easy to use.

John Antoniou Fackson Mwale David J. Zukor Olga L. Huk Alain Petit

Purpose: The presence of metal ions in the blood of patients with a metal-on-metal (MM) bearing points to the importance of understanding the long-term effects of these ions. Metal ions have the potential to induce the production of reactive oxygen species (ROS), making them prime suspects for inducing molecular damage in circulating cells. The aim of this study was to analyze the levels of oxidative stress markers in the plasma of patients with hip surface replacement.

Method: Blood was collected up to 3 years after implantation from 66 patients with articular surface replacement (ASRÔ, DePuy Orthopaedics) and 54 patients with 36 mm-head MM THA. Forty (40) pre-operative patients were also assessed as control group. Total anti-oxidant levels were measured by the Oxford Biomedical total antioxidant power assay (Oxford, MI) to obtain an overview of the defense capacity of patient’s oxidative stress. Peroxide concentrations were measured by the Biomedica OxyStat assay (Medicorp, Montreal, QC) to quantify damage to lipids in the systemic circulation. Nitrototyrosine levels were quantified using the BIOXYTECH® Nitrotyrosine-EIA assay (OxisResearch™, Portland OR) to measure damage to proteins. The concentrations of metal ions were analyzed by inductively coupled plasma-mass spectroscopy.

Results: Results showed that there were no statistical differences in the concentrations of total antioxidants, lipid peroxides, and protein nitrotyrosines between the control, the ASR, and the 36 mm-head groups. Furthermore, there was no correlation between the concentrations of these markers and the concentrations of both Co and Cr ions (r2 £ 0.006).

Conclusion: The single most significant obstacle preventing a broader application of metal-on-metal hip arthroplasties and resurfacings continues to be the concerns regarding elevated metal ion levels in the blood and urine of patients. The present results showed that there were no changes in the levels of oxidative stress markers in patients with MM bearings compared to the control group. Given the possible latency periods related to metal ion exposure, longer follow-ups are required to conclusively determine the effects of elevated circulating ions on oxidative stress in the blood of patients with MM bearings.

Colin P. McDonald James A. Johnson Terry M. Peters Graham J.W. King

Purpose: While computer-assisted techniques can improve the alignment of the implant articulation with the native structure, stem abutment in the intramedullary canal may impede achievement of this alignment. In the current study, the effect of a fixed valgus (6 degree) stemmed humeral component on the alignment of navigated total elbow arthroplasty was investigated. Our hypothesis was that implantation of a humeral component with a reduced stem length would be more accurate than implantation of the humeral component with a standard length stem.

Method: Thirteen cadaveric distal humeri were imaged using a CT scanner, and a 3D surface model was reconstructed from each scan. Implantation was performed using two implant configurations. The first set was unmodified (Regular) while the second set was modified by reducing the length of the humeral stem to 25% of the original stem (Reduced). A surface model of the humeral component was aligned with the flexion-extension (FE) axis of the CT-based surface model, which was registered to the landmarks of the physical humerus using the iterative closest point algorithm. Navigated implant positioning was based on aligning a 3D computer model calibrated to the implant with a 3D model registered to the distal humerus.

Results: Implant alignment error was significantly lower for the Reduced implant, averaging 1.3±0.5 mm in translation and 1.2±0.4° in rotation, compared with 1.9±1.1 mm and 3.6±2.1° for the Regular implant. Abutment of the implant stem with the medullary canal of the humerus prevented optimal alignment of the Regular humeral component as only four of the 13 implantations were aligned to within 2.0° using navigation.

Conclusion: These results demonstrate that a humeral component with a fixed valgus angulation cannot be accurately positioned in a consistent fashion within the medullary canal of the distal humerus without sacrificing alignment of the FE axis due to stem abutment. Improved accuracy of implant placement can be achieved by introducing a family of humeral components, with three valgus angulations of 0°, 4° and 8°. Based on humeral morphology for these specimens, 12 of the 13 implants may be positioned to within 2° of the native FE axis using one of these 3 valgus angulations.

Maeghan Innes Craig E. Tschirhart David D. McErlain David W. Holdsworth Karen D. Gordon Mark Hurtig

Purpose: The mechanical function and strain behavior of the knee meniscus is not fully understood, due to multiple tissues with disparate properties, as well as complex contact patterns and intricate loading mechanisms. More comprehensive understanding of joint mechanics may contribute to improved treatment options for patients with injuries and osteoarthritis. There is very limited information available on the 3D strain of the intact meniscus. The objective of this work was to use mCT with copper microsphere markers to quantify three-dimensional strain of the meniscus under physiologic loading.

Method: Two healthy fresh frozen ovine knee specimens were harvested. Copper microspheres (0.5mm) were injected into anterior and posterior tetrahedral clusters in the medial meniscus using 20-gauge hypodermic needles. Needle cavities were sealed with ovine tendon tissue. Joints were loaded to 100% body weight in a 4 DOF CT-compatible pneumatically-driven device with flexion angles ranging from 62–98°. Images were acquired with an eXplore Locus Ultra mCT scanner and reconstructed with commercial software. A time series of images were acquired with the joint unloaded, during static loading, and at a reduced load (25% BW).

Results: The average maximum principle strains in the anterior element of the two specimens at 62o of flexion increased by 21% during loading and decreased by 13% during unloading. The maximum principle strains were 28% larger in the anterior element than the posterior. The strains in the anterior element decreased by 6.5% with time following load application, and decreased by 16% with load reduction, yielding relatively low residual strain. Strains were 2% larger in the anterior portion with larger flexion angles.

Conclusion: The objective of this work was to develop a reliable method for quantifying 3D strains in the meniscus. Results support the notion that mCT imaging with copper microspheres in the meniscus may be a viable technique for more comprehensive 3D strain analysis. The relatively low residual strains measured in this study indicate that copper microspheres are stable markers in this application. This technique may be useful in directing future studies aimed at understanding the impact of meniscal pathologies and the success of repair techniques.

Omri Lubocsky Michael R. Hardisty David Wright Hans J. Kreder Cari Whyne

Purpose: The distribution of weight bearing area within the acetabulum is of importance in addressing trauma to the acetabulum, hip joint deformities and causes of osteoarthritis. According to Wolf’s law, bone density can indicate loading patterns experienced. The objective of this study was to characterize distributions of acetabular bone density patterns by regions in the normal population.

Method: CT scans of 22 subjects, mean age 70.6 with no evidence to hip joint pathologies were analysed. Bone density distribution maps were generated within AmiraDEV4.1 image analysis software using custom written plugins (Visage Imaging, Carlsbad, USA). Acetabular cup surfaces were semi-automatically segmented from the reconstructed CT volumes with an atlas-based approach. The acetabular cups were expanded 2.5 mm into the acetabular bone, and surface bone densities were calculated as the average bone density within ±2.5mm. The distribution maps were analysed using zones to spatially classify areas of high and low bone density in a healthy population. The acetabular cups were aligned using the acetabular rim plane that was landmarked, and by rotating the cups, such that a 900 abduction angle and a 00 anteversion angle were achieved. The grid used was divided to quadrants, and subdivided into radial thirds of the average rim radius. The correspondence of left and right density maps was investigated by comparing the average bone density in corresponding zones and across the population.

Results: High bone densities were found around the roof of the acetabulum aligning with the femoral mechanical axis during standing. The highest average bone density were found to be the superior and posterior walls of the acetabulum, corresponding to regions 8, 9, and 12 compared to other regions of the acetabuli (P< 0.01). A strong correlation was found between left and right sides within subjects (R=0.91, P< 0.05); and weaker correlation was also found for overall average bone density, (R=0.77, P< 0.05).

Conclusion: The location of the zones with the highest average bone density agrees with cadaveral studies of the maximum contact stress in the acetabulum (zones 9 and 12). [1,2]. It may explain why trauma to these areas carries a higher risk for early arthritic changes.

Colin P. McDonald James A. Johnson Terry M. Peters Graham J.W. King

Purpose: This study evaluated the accuracy of humeral component alignment in total elbow arthroplasty. An image-based navigated approach was compared against a conventional non-navigated technique. We hypothesized that an image-based navigation system would improve humeral component positioning, with navigational errors less than or approaching 2.0mm and 2.0°.

Method: Eleven cadaveric distal humeri were imaged using a CT scanner, from which 3D surface models were reconstructed. Non-navigated humeral component implantation was based on a visual estimation of the flexion-extension (FE) axis on the medial and lateral aspects of the distal humerus, followed by standard instrumentation and positioning of a commercial prosthesis by an experienced surgeon. Positioning was based on the estimated FE axis and surgeon judgment. The stem length was reduced by 75% to evaluate the navigation system independent of implant design constraints. For navigated alignment, the implant was aligned with the FE axis of the CT surface model, which was registered to landmarks of the physical humerus using the iterative closest point algorithm. Navigated implant positioning was based on aligning a 3D computer model calibrated to the implant with a 3D model registered to the distal humerus. Each alignment technique was repeated for a bone loss scenario where distal landmarks were not available for FE axis identification.

Results: Implant alignment error was significantly lower using navigation (P< 0.001). Navigated implant alignment error was 1.2±0.3 mm in translation and 1.3±0.3° in rotation for the intact scenario, and 1.1±0.5 mm and 2.0±1.3° for the bone loss scenario. Non-navigated alignment error was 3.1±1.3 mm and 5.0±3.8° for the intact scenario, and 3.0±1.6 mm and 12.2±3.3° for the bone loss scenario. Without navigation, 5 implants were aligned outside 5° for intact bone while 9 were aligned outside 10° for the bone loss scenario.

Conclusion: Image-based navigation improved the accuracy of humeral component placement to less than 2.0 mm and 2.0°. Further, outliers in implant positioning were reduced using image-based navigation, particularly in the presence of bone loss. Implant malalignment may well increase the likelihood of early implant wear, instability and loosening. It is likely that improved implant positioning will lead to fewer implant related complications and greater prosthesis longevity.

Dan Padmos Peng Zhang Michael J. Dunbar

Purpose: Component loosening is a leading cause of joint replacement failure. Modifying titanium surfaces with chemically bound functional proteins, such as bone morphogenetic protein (BMP), can efficiently strengthen the interface between prosthesis and bone. A prototype system was developed by using gold nanoparticles (AuNPs) to bridge lysozyme (compositionally similar to BMP) and titanium.

Method: For reference, lysozyme-conjugated gold nanoparticles (Lys-AuNPs) were prepared in solution via two different pathways:

gold compound was reduced in the presence of lysozyme to form Lys-AuNPs or

citrate-stabilized AuNPs were functionalized with mercaptopropionic acid (MPA) to produce carboxylic acid terminated AuNPs which were mixed with lysozyme.

Both solutions were characterized with transmission electron microscopy, ultraviolet-visible spectroscopy, circular dichroism spectroscopy (CD), and enzymatic assays. Next, AuNPs were prepared on 99.5% titanium foil discs (n=32) through electroless deposition. Deposition parameters were modified to create two groups of discs with different average diameters of AuNPs, measured by scanning electron microscopy. Some discs from both groups also underwent treatment with MPA. All discs were treated with lysozyme and the adsorbed amounts and activities of lysozyme were examined with micro BCA and enzymatic assays.

Results: Lysozyme and AuNPs can be conjugated in solution via two different pathways. CD results showed a significant change in the secondary structure of the lysozyme and decrease in enzymatic activity when directly conjugated to AuNPs; however, little change in secondary structure and enzymatic activity was observed for the lysozyme with MPA functionalized AuNPs. For the AuNPs on the titanium discs, SEM showed that the two groups had significantly different average AuNP diameters. Bioactive lysozyme was immobilized onto the discs and the results suggested that discs with the largest AuNPs treated with MPA had higher adsorption and activity of lysozyme.

Conclusion: A wet-chemical technique may be used to bind lysozyme to titanium via gold nanoparticles. Additionally, it was possible to control the size of the AuNPs on titanium which provides a good platform for further functionalisation with thiol molecules such as MPA. This technique holds promise for binding more functional molecules to surgical implants, hence creating “smart” implants that react to their local environment.

Mark Hurtig Laurent Fischer Antonio Cruz Frederick David

Purpose: To determine if an adenovirus vector expressing BMP-7 can alter the progression of post-traumatic osteoarthritis.

Method: Preliminary dose-response studies were done in ovine metacarpal-phalangeal joints using 10^9, 10^10, and 10^11 virus particles (VP). In-vitro transfection efficiency studies were done using ovine synovial cells, chondrocytes and HEK293 cells. In-vivo studies were conducted in 16 sheep that underwent surgery to create bilateral contusive impact injuries to the medial femoral condyle. One week later 10^9 VP were injected into one joint of each sheep, while four sheep remained untreated bilateral controls. Three months later the sheep were sacrificed for assessments including histological scoring, cartilage glycosaminoglycan assays, and immunostaining for Col2 3/4 short collagen fragments that are generated by metalloproteinases during OA progression.

Results: Transfection with 10^9 VP produced slightly longer expression than higher concentrations of VP. HEK293 cells expressed BMP-7 quickly but synoviocytes and chondrocytes expressed this protein at 48 and 96 hours. Knee joints that received Ad5-BMP-7 produced up to 2.5 ng of BMP-7 between day seven and 21. These joints had reduced cartilage degneration at the injury sites and less centrifugal progression of OA across the femoral condyle. Histological scores were reduced as was Col2 C3/4 short immunostaining.

Conclusion: BMP-7 has a homeostatic role in cartilage and can be used therapeutically1. Ad5-BMP-7 transfection of synovial tissue produced sufficient BMP-7 to stop the progression of degenerative changes after trauma that would usually lead to OA. Adenoviral vectors can create inflammation and neutralizing antibodies but these complications were minimized by using a low (10^9) dose. Human trials using similar vectors are ongoing and the outcome of these will determine whether gene therapy will become a useful tool when patients are at risk of post-traumatic OA.

Elizabeth A. Sled Latif Khoja Kevin J. Deluzio Sandra J. Olney Elsie G. Culham

Purpose: Hip muscle weakness may result in impaired frontal plane pelvic control during gait, leading to greater medial compartment loading, as measured by the knee adduction moment, in persons with knee osteoarthritis (OA). The purpose of this study was to evaluate the influence of an 8-week home-based strengthening program for the hip abductor muscles on hip muscle strength and the external knee adduction moment during gait in individuals with medial knee OA compared to an asymptomatic control group. Secondary objectives were to determine if hip abductor strengthening exercises would improve physical function and knee symptoms in this sample of people with knee OA.

Method: Forty participants with knee OA were age and gender-matched with an asymptomatic control group. Three-dimensional gait analysis was performed to obtain peak knee adduction moments in the first 50% of stance phase. Isokinetic concentric strength of the hip abductor muscles was measured using a Biodex Isokinetic Dynamometer. Functional performance was evaluated using the Five-Times-Sit-to-Stand test. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) provided an assessment of knee pain. Following initial testing, participants with knee OA were instructed in a home program of hip abductor strengthening exercises. All participants were re-evaluated after 8 weeks.

Results: There was no significant difference in isokinetic hip abductor muscle strength between groups at baseline or at follow-up. An improvement in hip abductor strength occurred in the OA group following the intervention (p = 0.036). The OA group had higher peak knee adduction moments than the control group (p = 0.006), but there was no change in the knee adduction moment over time in either group (p > 0.05). The OA group performed the sit-to-stand test more slowly than the control group (p = 0.001). At final testing, functional performance on the sit-to-stand test had improved in the OA group compared to the control group (p = 0.021). The OA group showed a trend towards decreased knee pain (p = 0.05).

Conclusion: An 8-week home program of hip abductor muscle strengthening did not reduce knee joint loading, but improved function, in a group of participants with medial knee OA.

Emily J. McWalter David R. Wilson William F. Harvey Kelly A. Lamb Paula I. McCree David J. Hunter

Purpose: Patellar bracing is a common, mechanical-based treatment strategy for patellofemoral osteoarthritis (OA). It is thought that the brace corrects patellar tracking, however, this correction has not been quantified in the OA population. Through advances in magnetic resonance imaging (MRI), we can now assess patellar tracking in three-dimensions.

Method: We assessed three-dimensional patellar tracking in ten subjects with symptomatic radiographic patellofemoral knee OA using a validated, quasi-static, MRI-based method. Four conditions were studied:

no knee brace, no load,

no knee brace, 15% bodyweight (BW) load,

knee brace, no load,

knee brace, 15% BW load.

Patellar tracking (flexion, spin and tilt; proximal, lateral and anterior translation) was assessed. Comparisons were made at 1° increments over the coincidental range of knee flexion between the no-brace and brace conditions, at no load and 15% BW load, using a paired t-test with Bonferroni correction.

Results: All subjects (7 female, 3 male, 60.9±1.3 yrs, 89.5±19.3 kg) had radiographic lateral patellofemoral OA and seven had concomitant tibiofemoral OA (KL grade≥2). Under no load, the brace extended (mean=2.7°, CI=[2.4°, 2.9°], P< 0.001) and medially tilted (mean=−1.4°, CI=[−1.6°, −1.2°], P< 0.001) the patellae and shifted them distally (mean=0.8mm, CI=[0.6mm, 0.9mm], P< 0.001), medially (mean=0.5mm, CI=[0.5mm, 0.6mm], P< 0.001) and posteriorly (mean=0.6mm, CI=[0.5mm, 0.6mm], P< 0.001). Under 15% BW load, the brace extended the patella (mean=2.4°, CI=[2.1°, 2.8°], P< 0.001) and shifted them distally (mean=1.3mm, CI=[1.1mm, 1.4mm], P< 0.001), medially (mean=0.8mm, CI=[0.7mm, 0.9mm], P< 0.001) and posteriorly (mean 0.6mm, CI=[0.5mm, 0.7mm], P< 0.001).

Conclusion: The brace extended the patellae for both loading conditions, suggesting that patellar flexion/extension is restricted by the brace. The brace tilted the patellae medially under no load only, suggesting when the quadriceps are active (15% BW load) the brace has little effect for tilt. While the effect of bracing on patellar tracking may appear small, the differences are of similar magnitude to those observed between normals and patients with patellofemoral pain, suggesting that braces may produce clinically significant changes in patellar tracking.

Marlis Sabo Katherine Fay Louis Ferreira Colin McDonald James A. Johnson Graham J.W. King

Purpose: Osteochondritis dissecans (OCD) of the capitellum most commonly affects adolescent pitchers and gymnasts, and presents with pain and mechanical symptoms. Fragment excision is the most commonly employed surgical treatment; however, patients with larger lesions have been reported to have poorer outcomes. It’s not clear whether this is due to increased contact pressures on the surrounding articular surface, or if fragment excision causes instability of the elbow. The purpose of this study was to determine if fragment excision of simulated OCD lesions of the capitellum alters kinematics and stability of the elbow.

Method: Nine fresh-frozen cadaveric arms were mounted in an upper extremity joint motion simulator, with cables attaching the tendons of the major muscle tendons to motors and pneumatic actuators. Electromagnetic receivers attached to the radius and ulna enabled quantification of the kinematics of both bones with respect to the humerus. Three-dimensional CT scans were used to plan lesions of 12.5% (mean 0.8cm2), 25%, 37.5%, 50%, and 100% (mean 6.2cm2) of the capitellar surface, which were marked on the capitellum using navigation. Lesions were created by burring through cartilage and subchondral bone. The arms were subjected to active and passive flexion in both the vertical and valgus-loaded positions, and passive forearm rotation in the vertical position.

Results: No significant differences in varus-valgus or rotational ulnohumeral kinematics were found between any of the simulated OCD lesions and the elbows with an intact articulation with active and passive flexion, regardless of forearm rotation and the orientation of the arm (p> 0.7). Radiocapitellar kinematics were not significantly affected during passive forearm rotation with the arm in the vertical position (p=0.07–0.6).

Conclusion: In this in-vitro biomechanical study even large simulated OCD lesions of the capitellum did not alter the kinematics or laxity of the elbow at either the radiocapitellar or ulnohumeral joints. These data suggest that excision of capitellar fragments not amenable to fixation can be considered without altering elbow kinematics or decreasing stability. Further study is required to examine other factors, such as altered contact stresses on the remaining articulation, that are thought to contribute to poorer outcomes in patients with larger lesions.

Fay Leung Clive P. Duncan Helen Burt John Jackson

Purpose: This study investigates the synergistic use of fusidic acid with vancomycin, and linezolid in poly-methylmethacrylate (PMMA) cement for the treatment of orthopedic MRSA and MRSE infections. Alone, Vancomycin is typically eluted in limited quantities from cement. The purpose of this study was to

combine FA and Vancomycin, and Linezolid alone in PMMA cement and characterize antibiotic elution, and

to improve drug release using polyethylene glycol (PEG) and NaCl in PMMA cement.

Method: Standardized 1g pellets of Palacos cement were manufactured containing Vancomycin and FA or Linezolid at increasing concentrations in three batches: without additive, with increasing concentrations of PEG, and with increasing concentrations of NaCl. The pellets were incubated in phosphate buffered saline and sampled at regular intervals. Drug analysis was performed with high pressure liquid chromatograpy.

Results: Total drug release at 2.5% loading of Vancomycin alone was 0.84% and of FA was 2.35%. Linezolid showed comparable release profiles. Vancomycin and FA combined yeilded Vancomycin release of 6.2% and FA of 8.4%. The addition of 30% PEG increased release of Vancomycin and Fusidic Acid by six-fold. The addition of 18% NaCl increased total Vancomycin release by 11-fold but had no effect on FA release.

Conclusion: Linezolid, Vancomycin and FA can be combined in PMMA and have favorable release profiles. The addition of PEG and NaCl dramatically increases the release of antibiotics, with the exception of FA and NaCl. These strategies may be useful in the management of MRSA/MRSE infections.

Paul-Edgar Beaulé David Allen Steve Doucette Othman Ramadan

Purpose: Femoroacetabular impingement (FAI) has recently been described as a cause of adult hip pain and a precursor of hip osteoarthritis. Pincer type is secondary to acetabular retroversion or coxa profunda and Cam type is secondary to lack of concavity/offset of the antero-lateral femoral head-neck junction. Purpose of this study was to determine the prevalence of bilateral deformity in patients with cam type FAI as well as the presence of associated acetabular abnormalities.

Method: One hundred and thirteen patients with symptomatic cam impingement (alpha (α) angle of Notzli > 55.5°) of at least one hip were evaluated. Eighty-two males, 31 females with an average age of 37.9 yrs (16–55). Standardized AP pelvis and bilateral Dunn views were reviewed. Alpha angle of Notzli was measured on Dunn views. Cam impingement was defined by α angle > 55.5 on the Dunn view and Pincer impingement was defined by the presence of either acetabular retroversion or coxa profunda. Statistical analysis was done using the two tailed paired t-test, chi-square test and intra-class correlation coefficient. Odds Ratios were calculated using conditional logistic regression.

Results: Eighty-eight patients (77.8%) had bilateral deformity and 27% had symptoms in both hips. Mean α angles were higher for bilateral impingement deformity than for the impingement side only when unilateral deformity was present (72.10 versus 64.50, p< 0.001). Forty-four percent of hips with an impingement deformity also had a pincer deformity, either acetabular retroversion or coxa profunda. Painful hips had a statistically significant higher mean alpha angle than asymptomatic ones (69.70 versus 63.10, p< 0.001)). Comparing hips with α angles of 61–70 with those < 60 found an odds ratio of being painful of 2.59 (95% CI: 1.32–5.08, p=0.006). Hips with α angles > 71 had an odds ratio of being painful of 2.54 (95% CI: 1.3–4.96, p=0.007).

Conclusion: The majority of patients with cam type FAI have bilateral deformities and an associated acetabular deformity less commonly. The severity of the deformity at the femoral head neck junction is a significant determining factor for the development of hip symptoms. This information is important as we better define the natural history of this deformity as well as devise effective treatment strategies.

Javad Parvizi Luis Pulido Madih Matar Nicole Marchetto Bora Og

Purpose: Femoroacetabular impingement (FAI) is recognized as an etiological risk factor for hip arthritis. The potential for joint preserving surgical techniques that may delay the progression to early arthritis and retard the possibility of arthroplasty at a young age is promising. This study presents the outcome of surgical treatment of FAI through a less invasive technique performed through a modified Smith-Peterson approach without hip dislocation, or arthroscopy.

Method: Using an institutional database, a total of 72 patients (80 hips) with radiographic and clinical diagnosis of FAI who underwent direct anterior femoroacetabular osteoplasty (FAO) were identified. Preoperative and postoperative functional evaluation was performed on these patients. The operative findings were recorded in detail and evaluated with regard to outcome.

Results: Intraoperative diagnosis of labral tear and osteochondral lesions in the anterosuperior acetabulum was confirmed in all cases. The surgical approach provided adequate access to allow labral repair and osteoplasty of the femoral neck and the acetabulum, whenever needed. There were no intraoperative complications. All patients experienced a significant improvement in function as measured by modified Harris hip and SUSHI scores. Majority (85%) of the patients were satisfied with the outcome of the surgery. In addition, Health Survey SF-36 showed most patients felt their health had improved significantly. The predictors of poor outcome were previous hip scope, lack of labrum for repair, large chondral lesions, and workman’s compensation status.

Conclusion: This study presents the early results of a less invasive surgical treatment for femoroacetabular impingement. This ongoing study shows that the described technique seems to be a viable approach for treatment of this painful condition in the young.

James D. Johnston Bassam A. Masri David R. Wilson

Purpose: Subchondral cortical and trabecular bone mineral density (BMD) may increase and/or decrease during different stages of osteoarthritis (OA) disease progression. 2D in-vivo imaging studies examining direct associations between increased proximal tibial BMD and knee OA offer conflicting results, which may be due to the inherent limitations of 2D BMD imaging tools. Our objective was to compare existing and novel 3D imaging techniques for distinguishing subchondral bone properties in OA and normal cadaveric tibiae.

Method: Eight intact cadaver knees from five donors (4M:1F; age: 77+/−10) were repositioned and scanned three times using QCT (0.5mm isotropic resolution, 0.15mSv dosage). BMD was assessed using

computed tomography absorptiometry (CT-OAM) which uses maximum intensity projections to assesses peak density values within subchondral bone, and

our novel computed tomography topographic mapping of subchondral density (CT-TOMASD) technique, which uses surface projections to assess both cortical and trabecular bone density at specific depths from the subchondral surface.

Average BMD at normalized depths of 0–2.5mm, 2.5–5.0mm, and 5.0–10mm from the surface were assessed using CT-TomasD. Regional analyses were performed consisting of:

medial/lateral (M/L) BMD ratio, and

BMD of a 10mm diameter core identified as having the maximum regional BMD.

Each bone was assessed for OA using a modified-KL scoring system: Normal (mKL=0); Early-OA (1–2); and Late-OA (3–4).

Results: OA was identified in four compartments of three tibiae (1 late OA+valgus, 1 late OA+varus, 1 early OA+neutral). Larger density differences between OA and normal knees were noted using CT-TOMASD compared with CT-OAM. CT-TomasD demonstrated that the two knees with late OA demonstrated M/L BMD ratios differing by more than 3.4 SD compared with normals, with peak cores higher than normals across all depths. The knee with early OA and neutral alignment demonstrated M/L ratios less than normals while core differences were highest proximally, with density becoming lower than normals with increasing depth.

Conclusion: CT-TomasD demonstrated larger differences between OA and normal subjects when compared with CT-OAM differences. This may be due to CT-OAM primarily assessing peak density within the thin subchondral cortical endplate; a region demonstrating fairly uniform peak densities within a limited range.

Paul-Edgar Beaulé Kalesha Hack Gina DiPrimio Kawan Rakhra

Purpose: A growing body of literature confirms that idiopathic OA is frequently caused by subtle, and often radiographically occult, abnormalities at the femoral head-neck junction or acetabulum that result in abnormal contact between the femur and acetabulum. This condition, known as femoroacetabular impingement, is a widely accepted cause of early OA of the hip. MRI is the imaging modality that is most sensitive in detecting cam morphology. There is currently little published data regarding the prevalence of abnormalities of the femoral head-neck junction in patients without hip pain or previous hip pathology. The primary aim of this project is to examine the incidence of cam morphology in a population without hip pain or pre-existing hip disease using non-contrast MRI.

Method: Two hundred asymptomatic volunteers underwent magnetic resonance imaging targeted to both hips. Subjects were examined at the time of MRI to document internal rotation of the hips at 90 degrees flexion and to assess for a positive impingement sign. The mean age was 29.4 years (range 21.4–50.6); 77.5% were Caucasian and 55.5% female. The Nötzli alpha angle was measured on oblique axial images through the middle of the femoral neck for each hip. A value greater than 50 degrees was considered consistent with cam morphology. Measurements were performed independently by two musculoskeletal radiologists.

Results: Twenty-six percent of volunteers had at least one hip with cam morphology: 20% had an elevated alpha angle on either the right or the left side, and 6% had bilateral deformity. The average alpha angle was 42.6 degrees on the right (SD=7.9) and 42.4 degrees on the left (SD=7.7). Internal rotation was negatively correlated with alpha angle (p< .05). Patients with an elevated alpha angle on at least one side tended to be male (p< .01).

Conclusion: The high prevalence of cam morphology in asymptomatic individuals is critical information in determining the natural history of FAI as well as establishing treatment strategies in patients presenting with pre-arthritic hip pain.

Deepthi Gorapalli Albert J.M. Yee Aiguo Zhang Marina Demcheva Cari Whyne J. Vournakis A. Seth

Purpose: There is interest in biologic strategies that can potentially treat degenerative disc disease (DDD). A new deacetylated derivative of a marine diatomic glycosaminoglycan (DEAC) was developed and incorporated into two sulphated hydrogel formulations; Gel 1 and 2. These materials were proposed to have a reparative effect on damaged tissue. Biochemical studies were conducted using primary human disc cell (HDC) cultures.

Method: HDCs were isolated from surgical specimens by sequential enzymatic digestion (pronase and collagenase). Time-course in-vitro studies were conducted on cell cultures treated with DEAC, Gel 1 or Gel 2 (28 day period). Proteoglycan content (alcian blue), cellular viability/proliferation (MTT assay), and type collagen II, aggrecan expression (RT-PCR, immunohistochemistry) was assessed.

Results: When compared to controls, the DEAC, Gel 1 and 2 treated HDC groups showed significant increases in proteoglycan content as early as day 12. The greatest effect was observed with Gel 1 (78.4±1.9 fold greater optical density compared to control, p < 0.05). The amount of proteoglycan quantified on DEAC treated HDCs on day 28 was 27.7±0.09 times higher than control (p< 0.05). MTT results demonstrated that Gel 1 group showed the highest viability over the study period (mean optical density 0.13+.01 versus 0.039+0.01 in controls). There were no significant differences in cell proliferation of Gel 2, DEAC and untreated control groups. RT-PCR and immunohistochemistry demonstrated expression of type II collagen and aggrecan consistent with the disc phenotype.

Conclusion: The results of this study demonstrates that formulations derived from poly-N-acetyl glucosamine (pGLcNAc) have positive effects of disc cell metabolism as quantified by proteoglycan content, cellular viability and proliferation, and the expression of key extra-cellular matrix molecules. The sulphated formulation of deacetylated pGLcNAc (Gel 1) appeared to have the greatest in-vitro effect followed by DEAC and the short fiber construct of Gel 2. It is possible that the pGlcNAc fibers in Gel 2 were not as soluble to the extent of DEAC due to their inability to form strong hydrogen bonds. This study shows promise towards ongoing evaluation of novel biomaterials for the potential DDD treatment through tissue regenerative or reparative schemes.

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Javad Parvizi Orhan Bican Kevin Bozic Chris Peters

Purpose: Hip arthroscopy has been used at an increasing frequency over the last few years. Majority of patients undergoing hip arthroscopy are young and active individuals who seek definitive therapy for a painful hip condition and wish to avoid undergoing a hip replacement. Although relatively successful, complications following hip arthroscopy occur. This multi-institutional study presents a worrisome and previously unrecognized complication of hip arthroscopy, namely chondrolysis that lead to accelerated development of end-stage arthritis.

Method: Using the computerized database in each institution, patients undergoing total hip arthroplasty between 1999–2008 who had received hip arthroscopy prior to arthroplasty were identified. 39 patients were identified to have undergone at least one hip arthroscopy on the affected hip prior to arthroplasty. There were 21 female and 18 male patients. The mean age of patients at the time of hip arthroscopy was 45.9 years. Data regarding demographics, comorbidities, preoperative diagnosis, number of previous procedures, and the details of the surgical procedure were compiled. Radiographs were evaluated.

Results: The median time from arthroscopy to arthroplasty was 14.8 months (range 2.2 months to 7 years). Fourteen patients (35%) underwent THA within 12 months of a previous hip arthroscopy and in nine of these patients the indication for hip arthroscopy was labral tear debridement. These patients despite having none to minimal arthritis at the time of arthroscopy developed accelerated arthritis within a year that necessitated hip replacement.

Conclusion: Hip arthroscopy can cause accelerated degenerative arthritis of the hip in some patients. We believe the subset of our patients who developed arthritis so early after hip arthroscopy may have suffered chondrolysis and/or chondral injury during the arthroscopy that resulted in progressive and aggressive arthritis of the hip within 12 months. Hip arthroscopy should be reserved for a select group of patients. All measures to minimize the possibility of chondrolysis and/or chondral injury should be exercised.

Qingan Zhu Jie Liu Tim Bhatnagar Wolfram Tetzlaff Thomas Oxland

Purpose: Recent studies have shown differences in short term spinal cord pathology between spinal column injury mechanisms, such as contusion and fracture-dislocation. Such differences may exist at longer time points, and thus survival studies are needed in the dislocation models. A more in-depth characterization of the dislocation model is needed for development of a mild-moderate cervical spine dislocation model in a rat that is suitable for survival studies. Specifically, our objective in this study was to determine the dislocation displacement that produces initial spinal column failure in a Sprague-Dawley rat model and to validate a consistent injury at the desired dislocation in-vitro and in-vivo.

Method: For the dislocation model, the dorsal ligaments and facets at C4–C5 were removed to mimic the type of posterior element fracture and ligament injury commonly seen in a bilateral fracture-dislocation. C3 and C4 were clamped together and held stationary while the clamp holding C5 and C6 was connected to an electromagnetic actuator and displaced dorsally to produce the injury while force and displacement were recorded. Twenty-eight isolated cervical spine specimens of Sprague-Dawley rats were used to determine dislocation displacement at initial spinal column failure. The C4–C5 segment sustained dislocation (> 3mm) injury at 0.05mm/s (n=11), 100mm/s (n=4) and 1000mm/s (n=13). Initial spinal column failure was defined at with maximum force during the dislocation. A dislocation displacement of 1.4mm was applied to 7 isolated specimens and 4 anesthetized rats at 430mm/s. The spinal column failure was inspected up to 3 days after injury, as well as hemorrhage of spinal cord in-situ.

Results: The dislocation displacement at in-vitro spinal column failure was 0.95mm±0.32 and not significantly different among specimens at the three dislocation speeds. Under a dislocation displacement of 1.4mm, rupture of the C4–C5 disc occurred in all in-vitro (0.67mm±0.38) and in-vivo (0.65mm±0.17) cases. SCI hemorrhage at epicenter was observed in 3 of 4 cases.

Conclusion: The initial spinal column failure in an innovative SCI model occurs at displacement between 0.65mm and 0.95mm. Dislocation displacement of 1.4mm results in spinal column failure consistently and SCI hemorrhage, and may be suitable for survival studies.

James C. Boak Philippe Gedet Marcel Dvorak Stephen Ferguson Peter Cripton

Purpose: The average age of people suffering spinal cord injuries in many countries is shifting toward an older population, with a disproportionate number occurring in the spondylotic cervical spine. These injuries are typically due to low energy impacts, such as a fall from standing height. Since a stenotic spinal canal (a common feature of a spondylotic cervical spine) can cause myelopathy when the spine is flexed or extended, traumatic flexion or extension likely causes the injury during the low energy impact. However, this injury mechanism has not been observed experimentally.

Method: To better understand this injury mechanism an in-vitro study, using six whole cervical porcine spines, was conducted. The following techniques were combined to directly observe spinal cord compression in a stenotic spine during physiologic and super-physiologic motion:

A radio-opaque surrogate cord, with material properties matched to in-vivo specimens, replaced the real spinal cord.

Sagittal plane X-rays imaged the surrogate cord in the spine during testing.

Varying levels of canal stenosis were simulated by a M8 machine cap screw that entered the canal from the anterior by drilling through the C5 vertebral body.

Pure moment loading and a compressive follower load were used to replicate physiologic and super-physiologic motion.

Results: Initial results show that a stenotic occlusion that removes all extra space in the canal in the neutral posture, without compressing the cord, can lead to spinal cord compression within physiologic ranges of flexion and extension. The spinal cord can also be compressed during slightly super-physiologic flexion and extension with only 25% canal occlusion. Physiologic loads and motions in the same spines did not cause cord compression when canal occlusion was 0%.

Conclusion: These results support the hypothesis that cervical spinal canal stenosis increases the risk of spinal cord injury because spinal cord compression was observed during motions and loads that would be safe for a non-stenotic spine. These results are limited primarily due to the use of a porcine spine. However, this new stenosis model and experimental technique will be applied to in-vitro human spine specimens in future work.

Qingan Zhu Claire Jones Tim Schwab Chad Larson Eyal Itshayek Lawrence Lenke Washington University Peter Cripton

Purpose: A long spinal fusion across the thoracolumbar region is sometimes applied in scoliosis. Adjacent level degeneration below these constructs has been documented. Treatment with an artificial disc replacement below the fusion has been proposed to prevent degeneration there. There is currently little data detailing the expected biomechanics of this situation. The objective of this study was to evaluate range of motion (ROM) and helical axis of motion (HAM) changes due to one- and two-level Maverick total disc replacement adjacent to a long spinal fusion.

Method: A multidirectional flexibility testing protocol with compressive follower preload was used to test seven human cadaveric spine specimens (T8-S1). A continuous pure moment ±5.0 Nm was applied in flexion-extension (FE), lateral bending (LB) and axial rotation (AR), with a compressive follower preload of 400 N. The motion of each vertebra was monitored with an optoelectronic camera system. The test was completed for the intact condition and after each surgical technique:

T8-L4 fusion and facet capsulotomy at L4–L5 and L5-S1;

L4–L5 Maverick;

L5-S1 Maverick.

Maverick total disc replacement and fusion with the CD Horizon system was performed. Repeated measures ANOVA was used to analyze changes in ROM and HAM of the L4–L5 and L5-S1 segments.

Results: Following L4-L5 Maverick replacement, L4-L5 ROMs tended to decrease slightly (on average from 6.2°±2.8° to 5.1°±3.8° in FE, 1.1°±1.1° to 0.9°±0.5° in LB and 1.3°±0.9° to 1.0°±0.6° in AR). With two-level Maverick implantation, L5-S1 ROMs tended to increase slightly in FE (from 6.6°±2.6° to 7.1°±3.9°), and to decrease slightly in LB (from 1.5°±0.9° to 1.0°±0.3°) and AR (from 1.5°±1.5° to 1.1°±0.6°), compared to the fused condition. As a trend, HAM location shifted posteriorly in FE and AR, and inferiorly in LB following Maverick replacement. However, neither ROM nor HAM at these two segments showed any significant change due to the implantation of one-or two-level Maverick total disc replacement in any of the three directions.

Conclusion: The present results suggested that lower lumbar segments with Maverick disc replacement exhibited intact-like kinematics in both extent and quality of motion.

Seyed-Parsa Hojjat Michael R. Hardisty Cari Whyne

Purpose: The objective of this study is to develop and utilize a highly automated microCT based analysis tool to quantify microstructural differences in bone due to metastatic involvement in whole rat vertebrae.

Method: First and Third lumbar vertebrae from healthy (n=4) and metastatically involved (n=4) rnu/rnu rats were excised for analysis (total of 8 vertebrae). Lytic metastases were developed via intracardiac injection of MT1 human breast cancer cells. The specimens were scanned using microCT at 17.5 microns isotropic resolution. A highly automated algorithm was developed for whole vertebral segmentation based on the microCT data, including the posterior elements (AmiraDev3.1). This was accomplished using an atlas-based method incorporating demons deformable registration followed by refinement through level set curvature evolution. Volumetric concurrency was used to compare segmentations generated by the automated algorithm to manually refined segmentations. The segmentations were up-sampled by 4 and edge-enhanced and further segmented using a thresholding technique to have a clear segmentation of the individual trabeculae without advancing into the bone marrow(AmiraDev3.1). The cortical shell was removed automatically before analyzing the trabecular structure. Cortical bone volume(CBV) was calculated by subtracting the volume of the full segmentation from the segmentation with no cortical shell. The interior segmentation was then used to calculate Trabecular Bone Volume(TBV), Trabecular Thickness(TbTh), Trabecular Separation(TbSp), Trabecular Number(TbN) based on the expressions described by Parfitt, et al(1983). Finally mean intercept length(MIL) was used to calculate the anisotropy of the trabecular tissue. Analysis were carried out on both the healthy and metastatically involved vertebrae.

Results: The automated algorithm including the level set method refinement produced good tracking of the boundaries of entire rat vertebrae. Consistent results yielded significant reduction in TBV, slight reduction in TbN and TbTh, and significant increase in TbS in metastatic vertebrae compared to healthy. no significant differences were observed in CBV. The metastatic vertebrae was also found to be significantly more anisotropic than the healthy group.

Conclusion: The accuracy of the highly automated algorithm developed in this study to analyze microstructure in whole rat vertebrae make it a suitable tool for further analyzing the effects of existing and new treatments for spinal metastases at a preclinical level.

Craig Mathison Reyhan Chaudhary Lauren Beaupré Tim Joseph Samer Adeeb Martin Bouliane

Purpose: The purpose of this study is to compare two fixation methods for surgical neck proximal humeral fractures with medial calcar comminution:

locking plate fixation alone and

locking plate fixation with intramedullary allograft fibular bone peg augmentation.

Method: Eight embalmed pairs of cadaveric specimens were utilized in this study. Dual energy X-ray absorptiometry (DXA) scans were initially performed to determine the bone density of the specimens. Surgical neck proximal humerus fractures were simulated in these specimens by creating a 1-centimeter wedge-shaped osteotomy at the level of the surgical neck to simulate medial calcar fracture comminution. Each pair of specimens had one arm randomly repaired with locking plate fixation, and the other arm repaired with locking plate fixation augmented with an intramedullary fibular autograft bone peg. The constructs were tested in bending to determine the failure loads, and initial stiffness using Digital Imaging Correlation (DIC) technology. The moment created by the rotator cuff was replicated by fixating the humeral head, and applying a point load to the distal humerus. A load was applied with a displacement rate of 4 mm/min, and was stopped approximately every 5 lbs to take a picture and record the load. This process was continued until failure of the specimens was obtained.

Results: The intramedullary bone peg autograft increased the failure load of the constructs by 1.57±0.59 times (p = 0.026). Initial stiffness of the construct was also increased 3.13±2.10 times (p = 0.0079) with use of the bone peg.

Conclusion: The stronger and stiffer construct provided by the addition of an intramedullary fibular allograft bone peg to locking plate fixation may help maintain reduction, and reduce the risk of fixation failure in surgical neck proximal humerus fractures with medial comminution.

David W. Sanders Ajay Manjoo Abdel-Rahman Lawendy Amit Badhwar Michael S. Gladwell

Purpose: Indomethacin may preserve tissue viability in compartment syndrome. The mechanism of improved tissue viability is unclear, but the anti-inflammatory effects may alter the relative contribution of tissue necrosis versus apoptosis to cellular injury. Existing studies have only considered indomethacin administration prior to induction of compartment syndrome. The purpose of this study was to determine the effect of timing of indomethacin administration on muscle damage in compartment syndrome, and to assess apoptosis as a cause of tissue demise.

Method: Twenty-four Wistar rats were randomized to elevated intracompartmental pressure (EICP) for either 45 or 90 minutes (30mm Hg). In the 45 min group, indomethacin was withheld (group 1), given prior to induction of EICP (group 2) or given 15 min prior to fasciotomy (group 3). In the 90 min group, indomethacin was withheld (group 4) or provided 30 or 60 minutes prior to fasciotomy (groups 5 and 6). Intravital microscopy and histochemical staining assessed capillary perfusion, cell damage and inflammatory activation within EDL muscle. Apoptosis was assessed using ELISA staining for caspase-3. Groups were compared with one-way ANOVA (p< 0.05).

Results: Perfusion improved in indomethacin-treated groups. Nonperfused capillaries decreased from group 1 (50.1±2.5), to groups 2 (38.4±1.8) and 3 (14.13±1.73)(p< 0.0001). Similarly, groups 5 and 6 had 25% fewer non-perfused capillaries compared to group 4 (p< 0.0001). Tissue viability improved in indo-methacin-treated groups. Groups 2 and 3 showed fewer damaged cells (1±0.5% and 8.7±2%) compared to group 1 (20±14%)(p< 0.0001). Groups 5 and 6 showed decreased cell damage (13±1% and 11±1%) compared to group 4 (18±1%) (p< 0.01). Apoptotic activity was present in compartment syndrome. At 30 minutes there were elevated caspase levels in EICP groups (0.47±0.08) compared to controls (0.19±0.02). However, indomethacin treated groups did not differ from controls with regards to caspase levels (p> 0.05).

Conclusion: Indomethacin decreased cell damage and improved perfusion in compartment syndrome. The benefits of indomethacin were partially time dependent; some improvement in tissue viability occurred regardless of timing of administration. Although apoptosis was common in compartment syndrome, the protective effect of indomethacin does not appear to be related to apoptosis.

Brad Yoo Daphne M. Beingessner

Purpose: To compare locking and non-locking single and dual plating constructs in maintaining posteromedial fragment reduction in a bicondylar tibial plateau fracture model. We hypothesized that posteromedial fragment fixation with medial and lateral non-locked constructs would tolerate higher loads than lateral locked constructs alone.

Method: Thirty adult-sized composite tibiae were identically fractured into an AO 41-C1.3 pattern. Six plate constructs were tested:

lateral 8-hole 3.5 mm conventional non-locking proximal tibial plate [CP];

CP + posteromedial 6 hole 3.5 mm limited contact dynamic compression plate [CP + LCDCP];

CP + postero-medial 6 hole 1/3 tubular plate [CP + 1/3 tubular];

8-hole 3.5mm Proximal Tibial Locking plate [PTLP];

8-hole 3.5 mm LCP (locking compression plate) proximal tibia plate [LCP];

9-hole Less Invasive Stabilization System [LISS] plate.

Specimens were cyclically loaded to failure or a maximum load of 4000N. Load at posteromedial fragment failure was recorded.

Results: Fragment failure occurred at the posteromedial fragment first. The CP + 1/3 tubular construct had the highest average load to failure (3040 N). In two instances, the CP + 1/3 tubular construct did not fail under the highest loads applied and was the only construct to have specimens that did not fail by 4000 N. The CP + 1/3 tubular plating construct demonstrated significantly higher load at failure compared with the PTLP (p=0.036), the LCP (p=0.004), and the LISS (p=0.012). The CP + 1/3 tubular group did not demonstrate a significant difference in load at failure when compared with the CP (p=0.093) or the CP + LCDCP (p=0.108). The LISS demonstrated a significantly higher load at failure compared to the LCP (p=0.046) but not to the PTLP (p=0.800).

Conclusion: The posteromedial fragment tolerated higher loads with the CP + 1/3 tubular plate construct. The superiority of the dual plate construct may in part be due to the unreliable penetrance of the posteromedial fragment by the laterally applied locking screws.

Mark McConkey Timothy D. Schwab Andrew Travlos Thomas Oxland Thomas J. Goetz

Purpose: Open reduction internal fixation with a volar plate is a popular surgical option for distal radius fractures. The pronator quadratus (PQ) must be stripped from the distal radius in this procedure. PQ is an important pronator of the forearm and stabilizer of the distal radioulnar joint. The purpose of this study was to investigate pronation torque in healthy volunteers before and after temporary paralysis of the PQ with lidocaine under EMG guidance.

Method: A custom-made apparatus was built to allow isometric testing of pronation torque at 5 positions of rotation: 90° of supination, 45° of supination, neutral, 45° of pronation and 80° of pronation. It was validated using a test-retest design with 10 subjects. For the study, 17 (9 male, 8 female) right hand dominant volunteers were recruited. They were tested at all 5 positions in random order and then had their PQs paralyzed with lidocaine. Repeat testing was performed in the same random order 30 minutes after injection. Three subjects underwent unblinded testing with saline injected instead of lidocaine.

Results: After paralysis of PQ with lidocaine, pronation torque decreased by 23.2% (p=0.0010) at 90° of supination, 16.7% (p=0.0001) at 45° of supination, 22.9% (p=0.0002) in the neutral position, 20.4% (p=0.0066) at 45° of pronation and 22.2% (p=0.0754) at 80° of pronation. All were statistically significant except 80° of pronation. Peak torque values before and after injection were highest in the supinated positions (8.2 Nm at 45° supination) and decreased gradually as the subjects were in more pronated positions (1.8 Nm at 80° pronation). The test-retest trial demonstrated no evidence of fatigue with repeated testing. The subjects who underwent injection of saline demonstrated no evidence of pronation torque loss secondary to pain or a pressure effect of the injectate.

Conclusion: This study demonstrated a significant decrease in pronation torque with controlled elimination of PQ function. Open reduction internal fixation of distal radius fractures damages the PQ. This may result in a pronation torque deficit. Functional significance of this loss should be shown. Pronation torque measurement may add to postoperative outcome analysis of surgical procedures about the wrist.

Steven J.M. MacDonald Robert L. Barrack Seth Rosenzweig Jeffrey F. Guerin Richard W. McCalden Eric Bohm Robert B. Bourne Cecil H. Rorabeck

Purpose: There are two broad-based categories of cementless femoral components performed during total hip arthroplasty: proximally coated versus fully porous coated. While both have enjoyed widespread clinical applications, there remains debate regarding differences in clinical outcome scores, relative incidence of thigh pain and the development of stress shielding. The purpose of this study was to investigate these variables in a multi-center prospective randomized blinded clinical trial.

Method: Between three centers 388 patients were enrolled in this clinical trial. 198 patients received a proximally coated tapered cementless femoral component (Synergy, Smith and Nephew, Memphis) and 190 patients received a fully porous coated cementless femoral component (Prodigy, Depuy, Warsaw). Patients were evaluated pre-operatively, at 3, 6, 12 months and annually thereafter, with multiple validated outcome measures including WOMAC, SF12, HSS, UCLA activity and thigh pain scores. A cohort of 72 patients underwent preoperative and postoperative DEXA scanning.

Results: 367 patients had a minimum of 2 years follow-up (average 6.4 years). There were no differences in age at surgery, BMI, or pre-operative clinical outcome scores (WOMAC, SF12, HSS, UCLA activity, thigh pain) between groups. There were no differences in any post-operative clinical outcome scores at any interval of follow-up. There were no differences in incidence of thigh pain between groups at any time. The only measurable difference between study groups was in bone mineral density evaluation. Bone density change in Gruen zone 7 was 23.7% with the Prodigy stem and 15.3% with the Synergy stem (p=0.011).

Conclusion: Both fully porous coated and proximally porous coated cementless stems performed well, with no clinical differences at a minimum of 2 years follow-up. Only bone mineral density evaluations could detect any differences between these femoral components designs.

Martin Lavigne Payam Farhadnia Pascal-André Vendittoli

Purpose: Clinical studies still show significant variability in offset and leg length reconstruction after 28mmTHA. Precise restoration of hip biomechanics is important since it reduces wear and improves stability, abductor function and patient satisfaction. There is a tendency to increase offset and leg length to ensure stability of 28mmTHA. This may not be needed with the more stable LDHTHA and hip resurfacing implants, therefore potentially improving the precision of the hip reconstruction. The aim of this study was to verify this assumption.

Method: Leg length and femoral offset were measured on standardized digital radiographs with a computer software in 254 patients (49 HR, 74 LDHTHA, 132 28mmTHA) with unilateral hip involvement and compared to the normal contralateral side.

Results: Femoral offset was increased in 72% of 28mmTHA (mean +3.3mm), 56% of LDHTHA (mean +1.0mm) and 8% of HR (mean −3.2mm) (intergroup differences p< 0.05). The mean LLI was greater after 28mmTHA (+2,29mm) vs. (−0.45mm for LDHTHA and −1.8mm for HR). The percentage of patients with increased leg length > 4mm was greater for 28mmTHA (11%) compared to LDHTHA (2.7%) and HR (2%).

Conclusion: The stability afforded by the larger head of LDHTHA reduces the surgeon’s tendency to increased leg length and femoral offset to avoid instability as during 28mmTHA. In addition, compared to HR, LDHTHA allows more precise restoration of equal leg length and femoral offset in patient with greater pre operative deformities (low femoral offset and LLI > 1cm). LDHTHA may represent the most precise method of hip joint reconstruction.

Peter Lewis Ali Al-Belooshi Michael Olsen Emil H. Schemitsch James P. Waddell

Purpose: The use of UHMW polyethylene acetabular liners is known to cause polyethylene wear related osteolysis, the major limiting factor in its use in the younger active patient. Modern alumina ceramic articulations have been developed in order to reduce wear and avoid polyethylene debris. This prospective randomized long-term study aims to compare the outcome between an alumina ceramic-on-ceramic (CC) articulation with a ceramic on UHMW polyethylene articulation (CP).

Method: Fixty-six hips in 55 patients with mean age 42.2 (range 19–56) each received uncemented components (Wright Medical) and a 28mm alumina head with acetabular liner selected via sealed envelope randomization following anesthetic induction. Subsequent regular clinical and radiologic follow up measured patient outcome scores and noted any radiological changes.

Results: Twenty-six CP hips and 30 CC hips were evaluated. One failure required revision in each group. Mean St Michael’s outcome score for each group with up to 10 years follow-up (median 8 years, range 1–10) was 22.8 and 22.9 respectively (p=0.057). Radiographs with a minimum 5 years post-operative follow-up were analyzed in 42 hips (23 CC and 19 CP). The mean time of wear measurement for the CC group was 8.3 years (SD 1.3, Range 4.8–10.1 years) and for the CP group was 8.1 years (SD 0.9, Range 6.1–9.2 years)(p=0.471). Wear was identified in all but one CP hip but in only 12 of 23 CC replacements. Mean wear in the CP group was 0.11mm per year and 0.02mm per year in the CC group (p< 0.001).

Conclusion: To our knowledge this is the first long term randomized trial comparing in-vivo ceramic-on-ceramic with ceramic-on-polyethylene hip articulations. Other than significantly greater wear in the polyethylene group there was no significant difference in long-term outcome scores between the two groups with up to 10 years of follow-up. The use of a ceramic-on-ceramic bearing is a safe and durable option in the young patient avoiding the concerns of active metal ions and osteolytic polyethylene debris.

Martin Lavigne Julie Nantel Alain G. Roy Francois Prince Pascal-André Vendittoli Marc Therrien

Purpose: Better clinical outcome is generally reported after hip resurfacing when compared to conventional 28mmTHA. This may simply be the consequences of biased patient selection, patient perception or the advantageous use of larger diameter femoral heads in HR. The true clinical benefits of HR can only be assessed by comparison with LDH-THA in a blinded randomized study to eliminate/reduce those biases. This was the aim of the study.

Method: Charnley class A patients were randomized between HR or LDH-THA and kept blinded for one year. Clinical data, gait analysis, postural balance evaluations and functional tests were performed pre-operatively at 3, 6, 12 and 24 months postoperatively. Fourteen normal patients served as controls.

Results: Twenty-four patients were assigned to each group. There was no significant difference in WOMAC, SF-36, activity scores, and patient satisfaction. A slight advantage was observed for HR during the functional reach test (postural balance) and for LDH-THA during the step test (speed, strength and balance), all other tests showing no differences. Both groups quickly reached controls value for all tests by 3 months.

Conclusion: We have failed to demonstrate a clear difference in outcome between HR and LDH-THA. Both groups fully recovered quickly. The postulated clinical advantages of HR over 28mmTHA most likely result from using a larger head in highly motivated patients. The only clear advantage of HR over LDH-THA remains proximal femoral bone conservation, although with the excellent durability of currently used femoral stems, HR has to demonstrate comparable survivorship before bone conservation is considered a true benefit.

Paul-Edgar Beaulé Benoit Benoit

Purpose: The short-term results of metal-on-metal hip resurfacing (HR) have been excellent. However, extensile approaches such as the posterior and trochanteric slide have been used to ensure proper component placement. The minimally invasive (MI) anterior Hueter approach is both muscle and vascular sparing to the femoral head. The purpose of this study is to evaluate the learning curve of this approach in performing hip resurfacing.

Method: The first 50 MI HR done by a single high volume arthroplasty surgeon were compared with his previous fifty procedures performed through a trochanteric slide osteotomy, with respect to (BMI, sex, etiology and age) were comparable (p=.372,.122,.143 and .353, respectively).

Results: Overall, the traditional transtrochanteric lateral approach took significantly longer to perform compared to MI RAH (97 versus 109 minutes, p=0.014). If we exclude the first 25 MI RAH cases (mean, 106 minutes), the difference is greater (89 versus 109 minutes, p=0.002). The mean femoral component stem to femoral shaft angle (SSA) was not significantly different between the two groups (MI RAH=142.7, lateral approach=140.0, p=0.053). The cup abduction angle (CA) was slightly different between the two groups (MI RAH 42.5°, lateral approach=39.2°, p=0.03). More patients had cup abduction angles in the 45°–55° range (p=0.009) in the MI HR group but none had a cup angle over 55° of abduction in either group. On the femur side, component positioning was comparable.

Conclusion: Based on our early results, the anterior-Hueter approach is a reasonable alternative to more extensile surgical approaches. Like any MI approach to hip surgery, great care has to be taken not to put the cups too vertical. Further long-term studies as well as comparisons to other approaches such as the posterior approach will determine if the anterior approach can be recommended for hip resurfacing.

Peter Lewis Michael Olsen Emil H. Schemitsch James P. Waddell

Purpose: While the durability of most uncemented femoral stems remains unknown, it is the aim of this study to demonstrate Echelon Primary femoral stem performance with regard patient outcome and overall implant survival.

Method: Between February 1998 and March 2007, 428 patients received the Echelon Primary stem. The mean age of each patient was 58.1 (SD 11.1, Range 20–87). Body mass index averaged 30.5 kg/m2 (SD 5.8, Range 17.7–58.2). The majority of patients received a Reflection uncemented acetabular component (91%) and an ultra high molecular weight polyethylene liner (76.5%), although the highly cross linked polyethylene is now used with increased frequency, used in 31% of hips since 2005. The majority of femoral heads were cobalt chrome (79.3%).

Results: Kaplan Meier survivorship for the Echelon Femoral stem with revision for aseptic loosening as end point at 100 months is 99.3% (95% CI 97.1–99.8). Taking revision for any reason as the end point the Kaplan Meier survivorship is 98.3% at 100 months (95% CI 95.9–99.3). A pre-operative WOMAC score was available for 345 of the 392 patients with mean score of 43.5 (95% CI 41.6–45.4). At the three-month post-operative review the mean WOMAC score was significantly increased to 74.54 (95% CI 72.7–76.3)(p< 0.001) and by 1 year 84.3 (95% CI 80.5–88.1). At subsequent years, the modified WOMAC score remained at a plateau of around 80. General health assessment using the SF-36 shows an improvement in the physical component score from 33.1 (95% CI 32.3–33.9) preoperatively to 42.6 (95% CI 41.7–43.6)(p< 0.001) at three months and 48.19 (95% CI 44.2–52.2) at latest follow up. The mental component scores increased from 48.7 (95% CI 47.6–49.9) to 51.4 (95% CI 50.3–52.4)(p< 0.001) and 53.5 (95% CI 50.3–56.6) respectively.

Conclusion: This large prospective review of the Echelon Primary femoral stems reveals an excellent survivorship of the stem with a 99.3% survival at 8 years with regard aseptic loosening and 98.3% survival including revision for any reason. Patient outcome scores are significantly improved and subsequently maintained. There have been no changes with regard to manufacture or design of the stem within the period of review.

Keegan Au Kristoff Corten Robert B. Bourne Cecil H. Rorabeck Andreas Laupacis Li Ka Shing

Purpose: A randomised controlled trial comparing fixation of a Mallory-Head prosthesis for total hip arthroplasty (THA) with and without cement was performed with average 19 years (range 17–21 years) of continuous follow-up.

Method: Two hundred and fifty patients were randomised to undergo THA using either a Mallory-Head THA prosthesis designed to be inserted with cement or one designed for cementless insertion. Both patients and those involved in outcome assessment were blinded to the type of implantation. Patients were followed yearly after the first post-operative year for outcomes including mortality, revision arthroplasty, and health-related quality of life assessment scores.

Results: Primary THA was performed with cement in 124 patients and without cement in 126 patients. Mean age at the time of surgery was 64 years, and 48% were female. During the period of review, there were 78 (31%) deaths in the cohort, and 75 (30%) patients underwent revision surgery. Kaplan-Meier survivorship analysis revealed significantly increased revision rates in cemented compared with cementless THA using failure of either component (p=0.01) or femoral component (p< 0.001) as endpoints. Although acetabular failure accounted for most revisions overall, no significant difference between groups was noted (p=0.075). With the exception of cost to quality adjusted life years, all quality of life outcome measures improved post-operatively and, although reducing modestly through the period of review, demonstrated no difference between groups at final follow-up.

Conclusion: This study has demonstrated a concerning high revision rate with both cemented and cementless THA in patients with a mean age of 64 years at the time of surgery, which significantly affected cost effectiveness. With the implants studied, cementless femoral fixation was superior to cemented, with no cementless femoral component failures through the duration of this study. This study demonstrates the importance of post-market surveillance and evidence-based improvements in THA design (i.e., bearing couples and fixation).

Mitchell J. Winemaker Anthony Staibano Danielle Petruccelli Justin de Beer Carlos Lopez

Purpose: We retrospectively reviewed the pre- and postoperative radiographs of 116 patients receiving primary THA in a high volume arthroplasty centre to evaluate technical causes for limb length discrepancy. We hypothesized that limb lengthening most commonly occurs as a result of low placement of the acetabular implant.

Method: A sample of 116 primary THA’s performed between 2005 and 2007 with complete one-year postoperative clinical outcomes scores and appropriate radiographs available on PACS were identified from a prospective arthroplasty database. Pre- and one-year postoperative AP bilateral hip radiographs were reviewed, and pre- and post-operative leg length discrepancy as well as the respective acetabular and femoral contribution to any postoperative leg length discrepancy (if present) were measured.

Results: We found that 19 THA’s out of 116 (16.4%) were lengthened greater than 8 mm. Mean difference from preoperative to postoperative leg length was 13.3 mm (SD 7.6 mm). A mean of 6.3 mm (SD 6.2 mm) in lengthening was contributed by the femoral stem, and 5.3 mm (SD 6.3 mm) of lengthening was contributed by placement of the acetabular implant (p=0.738). There was a significant correlation between lengthening of the limb and femoral placement of the stem (r=0.5, p< 0.0001). Likewise, there was a strong correlation between limb lengthening and low placement of the cup (r=0.6, p< 0.0001). Of those limbs that were lengthened greater than 8 mm, Oxford Hip Score at one-year post-operative was not correlated with over-lengthening (r=0.06, p=0.551).

Conclusion: These results support our hypothesis that limb lengthening is indeed due to low placement of the acetabular implant, and equally this was attributable to error in placement of the femoral stem. We conclude that with careful preoperative planning and intraoperative identification of the tear drop, a significant reduction in clinically relevant limb lengthening can be achieved.

Andrew Warner Douglas Naudie Xunhua Yuan Robert B. Bourne Cecil H. Rorabeck David Holdsworth

Purpose: Accurate acetabular cup positioning is essential to successful total hip arthroplasty (THA). Intra-operative navigation of the acetabular component can optimize positioning, but often necessitates registration of the pelvis in the supine position. The majority of surgeons use the lateral position, however, which hides commonly employed registration landmarks. The purpose of this study was to identify novel anatomical landmarks for use in navigated THA from the lateral approach.

Method: We identified 156 patients that underwent pelvic CT scans for non-orthopaedic reasons from which 60 patients (mean age 62 years; 30 males, 30 females) were included in the study. CT scans were analyzed with sophisticated software (region grow, isosurface creation, and geometry overlay features). Saved coordinates from each scan were inputted into the program MATLAB (Mathworks, Natick, MA), v7.0, on a Macintosh-based workstation. A code was created to be able to calculate the normal vector for both planes and then calculate the angle formed between the normal vectors. The anterior plane (pubic tubercle (PT) and anterior superior iliac spine (ASIS)) was defined in addition to a series of lateral planes by retaining the ipsilateral PT and ASIS from the anterior plane, plus a variable third landmark. Angles obtained were those between the anterior and lateral planes. Angle conversions between the planes were analyzed using a paired t-test with a p-value of < 0.05 accepted as significant.

Results: The list of landmarks acquired included those used for supine registration (PT and ASIS) in addition to: posterior superior iliac spine (PSIS); posterior inferior iliac spine, (PIIS); ischial tuberosity (IT); tuber-culum of the iliac crest (TIC); and a line drawn along the outer lip of the iliac crest. The angle between the anterior plane and the novel lateral planes did not show a significant level of variance for two of the proposed lateral planes (P< 0.05).

Conclusion: An imageless navigation system in THA that can be accurately employed in the lateral position will benefit many surgeons. The invariance in angle calculations for the lateral planes calculated using the PSIS and the TIC suggest that they could be novel pelvic landmarks for lateral plane registration.

Michael Olsen Edward T. Davis James P. Waddell Emil H. Schemitsch

Purpose: Hip resurfacing is a technically demanding alternative to total hip arthroplasty. Placement of the initial femoral guidewire utilizing traditional mechanical jigs may lead to preparatory errors and a high degree of variability in final implant stem-shaft angle (SSA). Intraoperative computer navigation has the potential to decrease preparatory errors and provide a reliable method of femoral component placement. The current study evaluated the accuracy and learning curve of 140 consecutive navigated hip resurfacing arthroplasties.

Method: Between October 2005 and May 2007, 140 consecutive Birmingham Hip Resurfacings were performed on 132 patients (107 male, 25 female). The mean age of the cohort was 51.2 years (range 25–82). Indications for surgery included osteoarthritis (n=136) and avascular necrosis (n=4). Preoperative templating was performed using digital AP unilateral hip radiographs. Neck-shaft angles (NSA) were digitally measured and relative implant stem-shaft angles planned. The central guidewire was drilled and verified intra-operatively using an imageless navigation system. Implant stem-shaft angles were assessed using 3 month post-operative radiographs.

Results: Pre-operative templating determined a mean NSA of 132.2 degrees (SD 5.3 degrees, range 115–160). The planned SSA was a relative valgus alignment of 9.5 degrees (SD 2.6 degrees). The post-operative SSA differed from the planned SSA by 2.5 degrees (SD 1.9 degrees, range 0–8). The final SSA measured within ±5 degrees of the planned SSA in 89% of cases. Of the remaining 11% of cases, all measurements erred in valgus. No cases of neck notching or varus implant alignment occurred in the series. The mean navigation time for the entire series was 18 minutes (SD 6.6 minutes, range 10–50). A learning curve was observed with respect to navigation time, with a significant decrease in navigation time between the first 20 cases and the remainder of the series. There was no evidence of a learning curve for implant placement accuracy.

Conclusion: Imageless computer navigation shows promise in optimizing preparation of the femoral head and reducing the introduction of mechanical preparatory factors that predispose to femoral neck fracture. Navigation may afford the surgeon an accurate and reliable method of femoral component placement with negligible learning curve.

Gisele M. Carriere Pierre Guy

Purpose: Decubitus ulcers and post-operative infections significantly impact patients’ outcome and resource utilization. The purpose of this study is to report incidence of post-surgical infection, decubitus ulcer and associations to 30-day in-hospital mortality among elderly Canadians admitted for hip fracture.

Method: Statistics Canada’s national Health Person-Oriented Information database of linked acute care hospital discharges was queried for fiscal 2001–02, 2002–03, 2003–04 creating a cohort of 67,434 hip fracture patients aged 60+. Demographics, comorbidities (enhanced Charlson Index), fracture type and treatment were used in logistic regression models to report odds ratios for outcomes.

Results: Women were 76% of the cohort, median age was 82 yrs. Decubitus ulcer was detected in 2.3% of hip fracture patients. Increased risk was indentified for trochanteric fractures (OR 1.14, p< .05), dementia (OR 1.25, p< .05) and increasing age (OR: 1.02, p< .05). Decubitus ulcer more than doubled to 2.9% for those with 1–2 comorbidities, increasing to 6.3% for 3+ comorbidities. Between 1.2% and 1.3% of the cohort developed a post-surgical infection/inflammatory response depending on method used to calculate 30-day follow-up. Compared to internal fixation, arthroplasty showed higher infection (OR: 1.38, p< .05). Overall cohort 30-day in-patient mortality was 7%. Selected complications were significantly associated to 30-day in-hospital mortality (decubitus ulcer OR: 1.51 p< .05, post-surgical infection/inflammatory response (OR: 1.52 p< .05). Trochanteric fractures (OR: 1.19 p< .05) and hemi-arthroplasty (OR: 1.10, p< .05) were associated to 30-day mortality. No significant variation was found between total arthroplasty and internal fixation for 30-day in-patient mortality.

Conclusion: Quantification of these rates and risk factors may offer normative values to measure health system performance and possibly reflect care strategies and delays to surgery. Results may identify target groups at risk for complications and potentially highlight the impact of clinical decisions such as performing arthroplasty for all (displaced and undisplaced) femoral neck fractures.

Vishal Upadhyay Ajay Sahu Charalambos P. Charalambous N. Harshawardena Heath P. Taylor Mark Farrar

Purpose: The aim of this study was to analyze the outcome of AO cannulated screws for undisplaced fracture neck of femur and find out the correlation in outcome with respect to co-morbidities in a general trauma unit in UK.

Method: A retrospective study was conducted using data from electronic patient record, clinical coding information, clinic letters and GP’s. 315 patients who underwent AO screws for fracture neck of femur during 2000 to 2004 were included. We looked into age, place of living, classification, mechanisn of injury, comorbidities, mobility before fracture, allergy, addictions, whether patient was anticoagulated, delay for theatre with reasons, length of stay in hospital, complications and treatment for complications. We assessed reasons for other admissions later on, need and type of another operation, consequently developed comorbidities, patient getting fracture of other side and its treatment, time and cause of death if happened?

Results: There were 81 males and 234 females in the study. Mean age of patients was 72 years (range 50–96 years). Non-union occurred in 19 patients (6%) and avascular necrosis occurred in 49 patients (15.5%). Reoperation with an arthroplasty was required in 69 patients (21.9 %). The incidence of avascular necrosis with internal fixation at 1 year was 31 (9.8%). Fifty-one (16%) patients died in 2 year period. The age, walking ability of the patient, and associated co-morbidities were of statistical significance in predicting fracture healing complications. We correlated our complications with comorbidities and found them more in patients with end-stage renal failure, steroid intake, osteoporosis and diabetes mellitus etc.

Conclusion: The rate of fracture healing complications and reoperations in patients with undisplaced fractures was high in our series with two year follow up. It was even higher in patients with age greater than 80 years and some specific comorbidities. We should also consider co-morbidities and age before deciding for internal fixation rather than only the fracture configuration (Treat patient not the X-rays). Outcome is multifactorial and depends on many predictive factors. Each patient should be evaluated carefully and we should treat the physiological age and not the chronological age.

Vishal Upadhyay Ajay Sahu Ravi Mahajan Heath Taylor Mark Farrar

Purpose: The aim of the study was to analyze the outcome of AO cannulated screws for fractures neck of femur in patients with Diabetes mellitus.

Method: Sixty-two patients aged 50 years or more (17 males & 45 females) who underwent AO screws for fracture neck of femur over seven years (1999–2005) and followed-up for a minimum of two years formed the study population. A retrospective review of data from electronic patient record (EPR), clinical coding, clinic & GP letters was made. Age, residential placement, Garden’s classification of fracture, mode of injury, associated other co morbidities, pre-admission mobilisation status, allergies, addictions and anticoagulation status details were collected.

Results: The mean age of patients was 67 years (range 52–96 yrs). Eleven patients died in two years time. Forty-one patients were less than 75 years of age and 21 patients were more than 75 years of age. All the patients more than 75 years of age had undisplaced intracapsular fractures. Thirteen patients were type I and 49 patients were type II diabetic. Non-union and avascular necrosis occurred in nine (17%) & 13 (26%) patients respectively. Revision surgery in the form of total hip replacement or hemiarthroplasty were performed in 21 (41%) cases. The incidence of avascular necrosis following osteosynthesis at one year was 14%. Age, control of diabetes, postoperative complications, pre-fracture mobilization status etc. Complications like wound infection were more principally in patients who had poorly-controlled diabetes.

Conclusion: Patients with diabetes mellitus have metabolic bone disease due to vasculitis. This increases the risk of complications associated with fracture fixation such as non-union, cut-through and avascular necrosis (AVN). The complications and revision surgery rate was high in patients with displaced fractures and with poorly controlled diabetes. Comorbidities like diabetes and patient’s age were also strong predictors of healing in addition to fracture configuration. Looking at very high complication and re-operation rate, our recommendation in patients with diabetes is primary hemiarthroplasty irrespective of femoral head displacement, if there age is more than 75 years.

Nicole Simunovic Sheila Sprague Mohit Bhandari

Purpose: Hip fractures are associated with a high rate of mortality and profound temporary and sometimes permanent impairment of independence and quality of life. While guidelines exist for the surgical treatment of hip fracture patients, the effect of surgical delay on mortality and other patient-important outcomes remains unclear. The objective of this systematic review and meta-analysis was to determine the effect of early surgery compared with delayed surgery on the risk of mortality, common postoperative complications, and length of hospital stay among elderly hip fracture patients.

Method: We searched MEDLINE and EMBASE for relevant prospective studies evaluating surgical delay in patients undergoing surgery for hip fractures published in all languages between 1966 and 2008. We identified additional studies through contacting experts, as well as hand searches of the bibliographies of relevant articles and the archives of orthopaedic annual meetings. Two reviewers independently assessed methodological quality and extracted relevant data. When necessary, we contacted authors for clarification of study design or to provide additional data. Data were pooled by use of a DerSimonian and Laird random-effects model based on the inverse variance method.

Results: Of 1917 citations identified, 16 observational studies, which included a total of 13,565 patients with complete mortality data, met our inclusion criteria. Irrespective of the cut-off for delay (24, 48, or 72 hours), earlier surgery (< 24, < 48, or < 72 hours) was significantly associated with a reduction in the risk of unadjusted one-year mortality (relative risk 0.55; 95% confidence interval, 0.40 to 0.75, p=0.0002) and adjusted mortality rates (relative risk 0.81; 95% confidence interval, 0.68 to 0.96, p=0.01). Earlier surgery also reduced in-hospital pneumonia (relative risk 0.59; 95% confidence interval, 0.37 to 0.93, p=0.02), pressure sores (relative risk 0.48; 95% confidence interval, 0.34 to 0.69, p< 0.0001) and hospital stay (weighted mean difference 9.95 days; 95% confidence interval, 1.52 to 18.39, p=0.02).

Conclusion: Earlier surgery reduced the risk of mortality, postoperative pneumonia, pressure sores, and length of hospital stay among elderly hip fracture patients suggesting that it may be warranted to reduce administrative delays whenever possible. However, potential residual confounding of observational studies may limit any definitive conclusions.

Joshua Gary Kelly Lefaivre Frank Gerold Michael Hay Charles M. Reinert Adam J. Starr

Purpose: Acetabular fractures in elderly patients are difficult problems with various treatment options. Our institution treats many of these patients with percutaneous acetabular fixation. We reviewed medical records and contacted patients to determine the rate of conversion to total hip arthroplasty.

Method: Our institutional trauma database was searched for all patients age 60 and older who had been treated with percutaneous screw fixation for an acetabular fracture. Seventy-nine consecutive patients (80 fractures) were identified. Medical records were examined to obtain peri-operative and follow-up information regarding the hospital course and conversion to total hip arthroplasty. A survivorship anaylsis was created with conversion to total hip arthroplasty as the censored event, and standard Kaplan-Meier curves were constructed. Five categorical variables were used to test for differences in survival of the native hip: age, sex, simple versus complex fracture pattern, closed versus limited open reduction, and occurrence of a medical complication.

Results: Seventy-five fractures had adequate clinical follow-up with a mean of 3.9 years (range 0.5 – 11.9 years). Average blood loss was 69 cc and there were no postoperative infections. 19/75 (25%) were converted to total hip arthroplasty at a mean time of 1.4 years after the index procedure. Survivorship analysis demonstrated a cumulative survival of 65% at 11.9 years of follow-up. There were no conversions to arthroplasty beyond 4.7 post-operatively. There were no statistically significant associations between conversion to arthroplasty and age, sex, closed versus limited open reduction, simple versus complex fracture pattern, and occurrence of a medical complication.

Conclusion: Percutaneous fixation is a viable treatment option for patients age 60 or greater with acetabular fractures. Rates of conversion to total hip arthroplasty are comparable to other treatment methods and if conversion is required, soft tissues are preserved for future surgery.

G. Yves Laflamme Benoit Benoit Stéphane Leduc Jonah Hébert-Davies

Purpose: The age of patients presenting with acetabular fracture has increased over the last ten years. Older patients tend to have patterns involving the anterior column with comminution of the quadrilateral plate. Our goal was to investigate the appropriateness of open reduction and internal fixation using the modified Stoppa approach for geriatric acetabular fractures.

Method: A retrospective review of patients over the age of 60 having presented to an academic level I trauma center over the course of four years. Twenty patients were identified and treated using the modified Stoppa approach with plating of the quadrilateral surface. Patients were evaluated clinically using both SF-36 and Harris Hip Score. Records and radiographs (using criteria described by Matta) were reviewed retrospectively.

Results: All patients were followed for a minimum of two years with no lost at follow-up. Mean age for patients at time of intervention was 68 years. Average blood lost was 800cc and surgical time was 130 minutes (range, 55–210). There was one traumatic injury to the obturator nerve and two patients were noted to have temporary weakness of the hip adductors postoperatively. Average Harris Hip Score and the SF-36 were improved significantly (p< 0.05). Significant lost of reduction was seen in two patients and was correlated to superior dome impaction (p < 0.0001). Three patients required re-intervention with a Total Hip Arthroplasty.

Conclusion: Internal fixation using the modified Stoppa approach to buttress the quadrilateral plate should be considered a viable alternative to total hip arthroplasty for the initial treatment of acetabular fractures of the anterior column in the elderly.

Kelly Lefaivre Wade Smith Philip Stahel Alan Elliott Adam J. Starr

Purpose: To evaluate the effect of the presence of femur fracture on mortality, pulmonary complications, and ARDS in trauma patients. In addition, we aim to compare the effects of other major musculoskeletal injuries to femur fractures on these outcomes.

Method: We retrospectively reviewed the trauma registry of two tertiary level trauma centers for a period of 12 years (1995–2007). We evaluated data points on all patients: gender, age, AIS scores, GCS, SBP, and ICD-9 codes for femur fractures and other major orthopaedic injuries. Outcome measures were death in hospital and occurrence of a pulmonary complication (Adult respiratory distress syndrome, fat embolism syndrome, pneumonia and respiratory failure) and ARDS as a sub-group. Logistic regression was used to evaluate the effect of these variables and the presence of femur fracture on the three outcomes (death, pulmonary complications, and ARDS). The effect of other major orthopaedic injuries in these models was also compared to the effect of femur fractures.

Results: There were 83, 349 patients, with 3, 433 deaths, evaluated in the initial regression models. Gender, GCS < 8, age> 60, blood pressure < 90, 4 AIS scores and femur fracture were all independent predictors of mortality. The strongest predictors of mortality were GCS < 8 (OR 16.976, 95% CI 15.176–18.990) and SBP < 90 (OR 6.835, 95% CI 6.046– 7.726). Femur fracture was an independent predictor of mortality (OR 1.480 95% CI 1.135 – 1.929). The presence of femur fracture was not a statistically significant independent predictor of pulmonary complication (OR 1.29, 95% CI 0.911–1.766) while gender, GCS, and 5 of 6 AIS scores were. Other musculoskeletal injuries were significant predictors, including pelvic ring fractures and spinal fractures. In the ARDS regression model, femur fractures were not an independent predictor (OR 1.127, 95% 0.636–1.999).

Conclusion: The risk of mortality and pulmonary complications is multifactorial; most affected by age, GCS at presentation, SBP at presentation, gender and injury severity. In this study, the presence of a femur fracture does independently increase the risk of death, but not ARDS or other pulmonary complications. There are other musculoskeletal injuries that have a greater effect on mortality and pulmonary complications.

Darren Costain Sarah L. Whitehouse Nicole L. Pratt Stephen E. Graves Ross W. Crawford

Purpose: The appropriate means of fixation for hemiarthroplasty of the hip is a matter of ongoing debate. Proponents of uncemented components cite the risk of perioperative mortality with cement implantation as justification for avoiding cement in certain patients. Because cement-related mortality is rare, we wished to compare the incidence of perioperative mortality in patients receiving cemented versus uncemented hemiarthroplasty using a large national database. Further, we wished to compare overall revision rate between fixation methods to assess their role in implant survivorship.

Method: All recorded hemiarthroplasty cases from the AOA National Joint Replacement Registry were cross-referenced to the Australian mortality data, and deaths at 1d, 7d, 28d, and one year were compared between groups. Further, subgroup analysis of monoblock, modular, and bipolar hemiarthroplasty were compared as a surrogate measure of different patient populations.

Results: Comparing all hemiarthroplasty procedures as a group, there was a a significantly increased mortality rate at day one post-operatively (p = 0.0005) when cement was used. By day 7, this trend reversed, revealing a reduced mortality risk with cement (p = 0.02). This trend reversal persisted at day 28 and one year post-operatively (p = 0.028 & p < 0.0001, respectively). With subgroup analysis, monoblock hemiarthroplasty revealed a similar trend reversal in early versus late mortality. Modular and bipolar hemiarthroplasty procedures failed to reveal a significant difference in mortality when cemented and uncemented components were compared at all time points. When fixation method was compared in different age groups, a favourable mortality rate was seen at one year when cemented monoblock components were used in patients aged 71–80, and in patients ≥81 years old (p = 0.005 & < 0.001, respectively). The opposite was true with cemented modular implants at one year in patients < 70 years old (p = 0.009). There was no significant difference in mortality between cemented and uncemented implants in any other age investigated. Revision rates were significantly higher in patients treated with uncemented hemiarthroplasty regardless of prosthesis type.

Conclusion: This study demonstrates a higher overall success rate, and comparable or reduced long-term mortality risk when cement is used in hip hemiarthroplasty.

Arvindera Ghag Pierre Guy Peter J. O’Brien Henry M. Broekhuyse Robert N. Meek Piotr A. Blachut

Purpose: Femoral and tibial shaft malunion may predispose to knee osteoarthritis but may also pose a problem for knee reconstruction; malposition of total knee prostheses being a known cause of early failure. Limb realignment may prove to be beneficial prior to proceeding with arthroplasty. The purpose of this study was to evaluate the outcome and effect of shaft osteotomy prior to total knee arthroplasty (TKA).

Method: A search of the trauma database between 1987 and 2006 was conducted. Twenty-two osteotomies were performed on 21 patients with femoral or tibial shaft malunion who had been considered for TKA. Mean age at osteotomy was 54 years and mean follow-up 86 months. Time intervals between surgical procedures and Knee Society scores were calculated. Patients were surveyed regarding pain relief and functional improvement.

Results: Femoral osteotomy improved mean Knee Society knee scores from 47 to 76 and function scores from 34 to 61. Tibial osteotomy improved knee scores from 53 to 82 and function scores from 28 to 50. Four osteotomies were complicated by nonunion and required further intervention. Osteotomy subjectively improved pain and function for a mean of 56 months. Femoral and tibial shaft osteotomy delayed TKA in 45% (10 cases) for a mean period of just over 6.5 years (89 and 73 months for femoral and tibial osteotomy respectively). Pre and post Knee society scores were: Femur: knee 56 to 88, function 41 to 72; Tibia: knee 65 to 85, function 25 to 57. One TKA was revised after 11 months due to valgus malalignment and was complicated by a wound infection. There were no other infections or wound complications. The procedure additionally relieved pain and improved function in the remaining 12 joints, not yet requiring arthroplasty.

Conclusion: Femoral and tibial shaft osteotomy may delay and possibly avoid TKA, relieve pain and improve function in patients who present with malunion and end-stage knee arthritis. The complication rate and clinical results of TKA following shaft osteotomy appear to be similar to primary TKA. This treatment strategy should be considered in younger patients with post traumatic osteoarthritis where significant femoral or tibial deformity is present.

Peter Lapner Emilio Lopez Felipe Pereira Salah Elfatori David Simon

Purpose: The upward migration index (UMI) is a useful radiographic parameter for assessment of disorders of the rotator cuff. Utility of the UMI as a prognostic indicator for outcome following cuff repair has not been previously studied. The objective of this study was to determine if an association exists between the pre-operative UMI and the improvement in clinical and quality of life outcome scores following arthroscopic rotator cuff repair.

Method: Patients with a full thickness tear of the rotator cuff who underwent an arthroscopic repair of the cuff were selected for review. Eighty-four patients were included in the series. Mean patient age was 55 (range 25–78). The UMI was measured by MRI, and patients were divided into three groups: < 1.25 (GROUP A), 1.25–1.35 (GROUP B) and > 1.35 (GROUP C). Outcome variables were the non-weighted Constant-Murley score, ASES and the WORC assessed at baseline, 6 month and 12 months post-operatively. The paired t-test was used to carry out comparisons in follow up and one-way ANOVA was used to carry out comparisons between groups.

Results: There were 9 patients in group A, 33 in group B and 42 in group C. The improvement in scores from baseline to 1 year were as follows: ASES; 21.1 (A), 32.6 (B), and 38.4 (C); Constant 21.4 (A) 19.8 (B), and 24.2 (C) and WORC 31.9 (A), 42.7 (B), and 44 (C). Statistically significant improvements were observed in all groups in all outcome measures from baseline to 6 months and from 6 months to 1 year. Although the differences were not statistically significant (p> 0.05), a trend toward greater improvement in outcomes was observed with higher upward migration indices.

Conclusion: A lower UMI was associated with less improvement in functional and quality of life outcomes following arthroscopic rotator cuff repair, although these differences were not statistically significant. Patients with a low UMI demonstrated a significant improvement in functional and quality of life scores following surgery. In isolation, a low UMI should not represent a significant contraindication to treatment by arthroscopic rotator cuff repair.

Gerard Slobogean Akin Famuyide Vanessa Noonan Peter J. O’Brien

Purpose: To quantify how well the physical examination of the shoulder predicts patient-reported functional outcome in a cohort of patients with previous proximal humerus fractures.

Method: Potential subjects were identified from a recent study cohort of proximal humerus fracture patients treated within the past six years. The cohort consisted of all fracture types and treatment modalities. Participants underwent a focused physical examination of their injured shoulder containing the components of the Constant-Murley shoulder score: range of motion for forward flexion, abduction, internal rotation, external rotation, and abduction strength measured by an IsoBex muscle strength analyzer. Participants also completed the following patient-reported functional outcome questionnaires: Disabilities of Arm, Shoulder, Hand (DASH), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Simple Shoulder Test (SST), and Oxford Shoulder Score (OSS). Forward- and backward-stepwise linear regression was used to assess the relationship between the functional outcomes and the physical exam measurements.

Results: Thirty-one subjects with a mean age of 70 ± 8 years participated. Sixteen patients were previously treated with ORIF and 15 were treated with sling immobilization. The mean physical examination measures were: flexion 117° ± 31°, abduction 117° ± 37°, internal rotation 7° ± 2°, external rotation 7° ± 4°, and strength 6 ± 5 Newtons. The mean functional outcome scores were: DASH 21 ± 19, ASES 82 ± 17, SST 8 ± 3, and Oxford 20 ± 8. Using linear regression, adjusted R-squared statistics suggest components of the physical exam can explain 38% of the Oxford, 50% of the DASH, 58% of the SST, and 70% of the ASES variance. Abduction strength was a significant predictor for all functional outcomes. Combinations of flexion, abduction, or internal rotation were also significant predictors depending on the outcome instrument being modeled.

Conclusion: Physical exam of the shoulder accounts for differing amounts of patient-reported functional outcome variance. Abduction strength is the most consistent predictor of functional outcome within this cohort of proximal humerus fracture patients.

Ramin Mehin Peter O’Brien Penny Brasher Henry M. Broekhuyse Piotr Blachut Robert N. Meek Pierre Guy

Purpose: Problem: Tibia plateau fractures may lead to end-stage post-traumatic arthritis that requires reconstructive surgery. The incidence of this problem is unknown but has been estimated at 20–40% by studies that were limited by small sample sizes, potential follow-up bias, and the limitations of using radiographic arthritis as a chosen outcome (not correlated to function). The use of administrative data bases to follow the care of a large number patients for robust end points such as surgery, offers an opportunity to address these limitations. Purpose: to determine the minimum ten year incidence of post-traumatic arthritis necessitating reconstructive surgery following tibia plateau fractures.

Method: We queried our prospectively collected Orthopedic Trauma Data base to identify operatively treated patients with tibia plateau fractures. These cases were cross-referenced with the data from our Province’s administrative health database and tracked over time for the performance of reconstructive knee surgery. Each individual’s exposure/follow-up period was limited by end of health plan coverage on record or date of death from vital statistics data. The minimum follow-up was ten years.

Results: Between 1987 and 1994, 378 patients with a tibia plateau fracture were treated at our institution. The average age was 46 years (sd=18, range 14–87), while 56% of patients were males. Seventeen out-of-Province residents were excluded, along with forty-six others whose “Medical Services Plan” numbers could not be identified. Of which seven were WCB patients and one who was affiliated with the military. The study cohort therefore consisted of 311 patients with 314 tibia plateau fractures. Four individuals (1.3%) we treated tibia plateau fractures have required reconstructive knee surgery for end-stage post-traumatic knee arthritis at 10 years. Of these 3 of 4 were type VI fractures and 1 of 4 was open.

Conclusion: Patients who require surgical treatment of tibia plateau fractures may be counseled on their long-term risk of requiring reconstructive knee surgery for endstage knee arthritis based on a clinical study. Based on our findings, the proportion of those who have required a total knee surgery, ten years following their injury, is lower than previously published.

Richard M. Holtby Helen Razmjou Iona MacRitchie

Purpose: There is controversial information on recovery of patients with compensable injuries. The purpose of this matched case-control study was to examine the impact of an active compensation claim following a work-related shoulder injury on reporting disability as measured by subjective and objective outcomes at 1 year post-operatively.

Method: Data of 506 consecutive patients who had undergone a decompression or rotator cuff repair were reviewed. One hundred and fourteen patients were on compensation related to their shoulder problems. Patients were matched with a historical control group (patients without a compensation claim) based on age (4 age groups: < 40, 40–49, 50–59, 60–70), sex, and pathology (full-thickness tear vs. no tear). Outcome measures used were a disease-specific outcome, the Western Ontario Rotator Cuff Index (WORC) and two shoulder specific instruments, the American Shoulder and Elbow Score (ASES) and the Constant Murley (CM) score. Paired and independent t-tests and an analysis of covariance were performed.

Results: Data of the 214 patients (72 males and 35 females in each group) was used for analysis (mean age 48, SD: 10, range 20–69). Out of 107 patients in each group, 42 patients (58%) had undergone a full-thickness repair and 65 (61%) had surgeries related to impingement syndrome. Paired and independent t-tests showed that both groups improved significantly regardless of their claim status. However, the compensation group had a significantly lower level of improvement than the non-compensation group. An analysis of covariance which adjusted for pre-operative differences in disability scores showed that an active claim was indeed a strong predictor of follow up scores.

Conclusion: This is the first study that has used a matched case-control design to control for potential confounding factors in injured worker population. Our results indicate that although patients with work-related injuries demonstrate a lower level of recovery, they still benefit from surgery.

Peter Lapner Philippe Poitras Othman Ramadan Stephen Kingwell Donald Russell

Purpose: Subacromial impingement syndrome is a painful condition which occurs during overhead activities as the rotator cuff is compressed between the greater tuberosity and the acromion. Unrecognized secondary causes of impingement syndrome may lead to treatment failure. Posterior capsular tightness, believed to alter shoulder joint kinematics, is often cited as a secondary cause but scientific evidence is lacking. The objective of this study was to evaluate the effect of posterior capsular tightness on pressure in the subacromial space.

Method: Ten fresh-frozen cadaver shoulder specimens were mounted on a custom testing apparatus. With the scapula fixed, the deltoid and cuff muscles were loaded statically with a constant ratio to elevate the humerus in the scapular plane under physiologic loading conditions. For each treatment (intact capsule, 1cm and 2cm plication), pressure in the subacromial space and glenohumeral kinematics were recorded during elevation. The treatment order was randomly assigned to each specimen. Peak pressure and translation of the humeral head center were compared using a repeated measures ANOVA.

Results: Peak subacromial pressures (mean±sd) were similar between treatment groups: 345±152 kPa, 410±213 kPa and 330±164 kPa for the intact, 1cm and 2cm plication respectively (p> 0.05). No significant differences were found for superior or antero-posterior translations of the humeral head at the peak pressure position (p> 0.05).

Conclusion: Posterior capsular tightness, as a sole variable, did not contribute significantly to increased pressure in the subacromial space or to increased anterior or superior humeral head translation during abduction. Clinically, posterior capsular tightness may occur in association with impingement syndrome but may not play a significant role in causation.

Frédéric Balg Josianne Lepine Nicolas Huppe Eve Langelier Denis Rancourt

Purpose: Comparer la technique de réparation de la coiffe des rotateurs par haubanage tendineux en simple rangée aux techniques transosseuse et double-rangée par rapport à la surface et la pression de contact à l’interface tendon-os, et la force de rupture.

Method: Pour tester la pression et la surface de contact, les techniques de réparation ont été faite sur 2 spécimens cadavériques (tête humérale et sus-épineux) chaque. Un film Prescale pressure-sensing a été interposé entre les tendons et l’os pendant 2 minutes avec une tension de 120N sur les tendons. Les films ont été numérisés pour l’analyse avec le logiciel ImageJ. La force de rupture a été testé sur un modèle Sawbones d’humérus proximal. Des tendons synthétiques en fibre de nylon et polyesther dans du silicone ont été créés pour les propriétés d’un tendon proportionnellement à la rigidité du Sawbones. La force a été appliquée à 135° jusqu’à rupture sur 2 montages par technique de réparation. La suture transosseuse utilisait 2 fils Orthocord dans 2 tunnels transosseux. La suture double rangé a été faite avec 2 ancres Spiralok médialement et 2 ancres Versalok latéralement avec des fils Orthocord. Le haubanage tendineux a été fait avec 2 ancres Panalok RC latéralement dans la zone corticale.

Results: La surface de contact du haubanage de 17mm2 était significativement plus basse que de la suture transosseuse à 48mm2 (p=0.002) et double-rangée à 86mm2 (p=0.001). La différence entre transosseux et double rangée était significative (p=0.029). La pression de contact du haubanage de 0.353MPa était significativement plus basse que de la suture transosseuse à 0.441MPa (p=0.002) et double-rangée à 0.567MPa (p=0.003). La différence entre transosseux et double rangée était significative (p-0.029). La force de rupture du haubanage de 106N était significativement plus basse que de la suture transosseuse à 249N (p=0.03) et double-rangée à 316N (p=0.04). La différence entre transosseux et double rangée n’était pas significative.

Conclusion: Le haubanage tendineux ne reproduit pas l’empreinte anatomique du sus-épineux sur la grande tubérosité ni une pression de contact adéquate en plus d’avoir une force de rupture plus faible. Malgré son coût plus élevé, la suture par double rangée est supérieure à la technique transosseuse ou simple rangée.

Peter Zarkadas Thomas Throckmorton Diane Dahm John Sperling Robert Cofield

Purpose: The indication to perform a total shoulder arthroplasty (TSA) versus a hemiarthroplasty is guided by a patient’s intended level of activity after surgery. It is unclear what activities patients actually perform following shoulder replacement, therefore, the purpose of this study was to compare the self-reported activities of patients following either a TSA or hemiarthroplasty.

Method: Two groups of 75 patients each, following TSA or hemiarthroplasty, were matched for a variety of demographic variables. A mailed activity questionnaire asked patients to report their level of pain, motion, strength, and a choice of 70 different activities. Reported activities were classified as high (i.e. tennis) or low (i.e. fishing) demand, and categorized as household (i.e. cooking), yard work (i.e. gardening), sporting (i.e. golf), or musical (i.e. piano).

Results: Ninety-six (64%) patients completed the survey, 50 in the TSA group (27F:19M, avg. 53.2 yrs), and 46 in the HA group (29F:21M, avg. 53.5 yrs). Pain was not different between groups (3.6/10 TSA: 3.9/10 HA), yet a significant difference was reported in forward flexion (145° TSA: 120° HA, P< .002) and strength (6.3/10 TSA: 5.3/10 HA, P< .01). Across all categories whether it be high or low demand, the TSA group (10.4 activities/person) reported more activities compared with the hemiarthroplasty group (8.6 activities/person).

Conclusion: The conventional understanding that a hemiarthroplasty provides the possibility for more activity following surgery is not supported by our data. Patients following a TSA reported better motion and strength and were more active than the hemiarthroplasty group.

Robert Litchfield Michael D. McKee Robert A. Balyk Scott J. Mandel Richard M. Holtby Robert Hollinshead Robert MacCormack Darren S. Drosdowech Sharon H. Griffin

Purpose: This prospective, randomized double-blinded clinical trial compared cemented fixation of the humeral component to uncemented/tissue-in-growth fixation in total shoulder arthroplasty for primary osteoarthritis of the shoulder.

Method: All patients presenting with primary osteoarthritis of the shoulder requiring replacement were screened for eligibility. Patients were randomized in the operating room after glenoid preparation to the cemented or uncemented group by a computer-generated, stratified randomization procedure. Outcome measures included disease specific QOL assessment (WOOS), SF-12, ASES, MACTAR, radiographic evaluation of component fixation, operative time, complications and revision surgery. Patients were assessed by a blinded evaluator in post-operative intervals of 2 and 6 weeks, and 3, 6, 12, 18, and 24 months. The primary endpoint was the WOOS score at 2 years.

Results: One hundred and sixty-one patients were consented and randomized for the study. There were 80 patients in the cemented and 81 patients in the uncemented group. At baseline, the groups were alike with regards to demographics and baseline evaluations. The WOOS scores at post-operative intervals of 12, 18 and 24 months showed a significant difference (p=0.009, 0.001, 0.028 respectively) in favour of the cemented group. The cemented group also had better strength (3 m p=0.038, 12 m p= 0.036, 18 m p=0.051, 24 m p=0.053) and forward flexion (6m p=0.031, 12 m p=0.04). As expected, the operative time was significantly less for the uncemented group (C = 2.26h +/−.63; U = 1.69h +/− 1.9, p= 0.03).

Conclusion: These findings provide the first evidence that cemented fixation of the humeral head provides better quality of life, strength and ROM than uncemented fixation. This was a Tier 1 Project of the JOINTs Canada group.

Patrick Denard Timothy Bahney Robert M. Orfaly

Purpose: Determine the ideal form of subacromial decompression.

Method: Six cadaveric shoulders with intact rotator cuffs (RTC) underwent “smooth & move (SM),” limited acromioplasty with coracoacromial ligament (CAL) preservation, and CAL resection. Glenohumeral translation was measured in four directions utilizing electromagnetic spatial sensors. Peak RTC pressure was measured during arm abduction utilizing pressure film sensors.

Results: Anterosuperior translation was unchanged after SM or acromioplasty, but increased from 2mm at baseline to 4mm following CAL resection with the arm at 300 abduction (p=0.03). There were no significant changes in other directions of translation following any procedure. In neutral humeral rotation RTC pressure was unchanged after SM (p=1.00). Pressure decreased 64% after a limited acromioplasty (p=0.04), and 72% after CAL resection (p=0.03). There was a trend towards increased abduction at which peak pressure occurred following CAL resection (760 compared to 620;p=0.11) In external rotation, RTC pressure decreased 26% following SM, 52% after limited acromioplasty, and 64% after CAL resection, but values were not statistically changed (p=0.52, p=0.08, and p=0.06). Similarly, abduction angle at which peak pressure was reached increased but was statistically insignificant after SM (720; p=0.75), limited acromioplasty (750; p=0.11), and CAL resection (790; p=0.08). In internal rotation, RTC pressure decreased 32% following the SM, 59% following the limited acromioplasty, and 58% following CAL resection, but none reached statistical significance (p=0.52, p=0.26, p=0.17). Abduction angle of peak pressure was unchanged after SM (670; p=0.63) and limited acromioplasty (670; p=0.63), but increased following CAL resection (620 vs. 790; p=0.04).

Conclusion: A CAL resection leads to increased anterosuperior instability. “Smooth and move” or acromioplasty can safely be performed without increasing translation. Rotator cuff pressure did not significantly decrease after SM. Rotator cuff pressure was significantly decreased to a similar degree following a limited acromioplasty or a CAL resection. A limited acromioplasty with preservation of the CAL may offer the greatest decrease in cuff pressures without the undesirable effect of increased translation. However, statistical significance was affected by high anatomic variability. Therefore, the choice between “smooth & move” and acromioplasty to decrease contact pressure is likely best to be individualized based on acromial morphology.

Ryan Bicknell Pascal Boileau Yannick Roussanne Nicolas Brassart Chris Chuinard

Purpose: We hypothesized that lateralization of the RSA, with a glenoid bone graft taken from the osteotomised humeral head, would prevent those problems without increasing torque on the glenoid component by keeping the center of rotation within the glenoid. The objectives of this study were to describe the results of the first 12 patients that underwent a bony increased-offset RSA (BIO RSA).

Method: Thirty-six shoulders in 34 consecutive patients with cuff tear arthritis (mean age 72 years, range 52–86 years) received a BIO RSA, consisted of a RSA incorporating an autogenous humeral head bone graft placed beneath the glenoid baseplate. A baseplate with a lengthened central peg (+25 mm) was inserted in the glenoid vault, securing the bone graft beneath the baseplate and screws. All patients underwent clinical and radiographic (computed tomography) review at a minimum 1-year follow-up.

Results: All patients were satisfied or very satisfied and all had no or slight pain. Mean active elevation increased from 72° to 142° (p< 0.05), external rotation from 10° to 18° (p< 0.05) and internal rotation from L4 to L3 (p> 0.05). Constant Score improved from 27 to 63 points (p< 0.05). The Subjective Shoulder Value (SSV) increased from 27% to 73% (p< 0.05). Radiographically, the graft healed to the native glenoid in all cases and no graft resorption under the baseplate was observed. Complications included one patient with scapular notching (stage 1) and one patient with previous radiotherapy had a deep infection. No postoperative instability, and no glenoid loosening were observed.

Conclusion: The use of an autologous bone graft harvested from the humeral head can lateralize the center of rotation of a RSA while keeping the center of rotation at the glenoid bone-prosthesis interface. The clinical advantages of a BIO RSA are a decrease in scapular notching, enhanced stability and mobility, and improved shoulder contour while keeping the center of rotation at the glenoid bone-prosthesis interface. This bony lateralization allows maintenance of the principles of Grammont and seems to be more appropriate than prosthetic lateralization. These promising early results of this novel procedure warrant further investigation.

Ryan Bicknell Frederick A. Matsen Alex Bertelsen Paul Pottinger

Purpose: The objectives of this study were to correlate the clinical course of all patients with positive intra-operative P. acnes cultures in revision shoulder surgery with the cultures and intraoperative findings to determine the clinical significance of the positive cultures.

Method: From 2005 to 2007 all revision shoulder surgeries were managed with a standard protocol in which

antibiotics were withheld until cultures obtained,

at least four fluid and tissue cultures were submitted,

frozen sections were obtained of any tissue grossly suspicious for infection, and

the surgeons’ pre-, intra-, and post-operative suspicion for infection were recorded.

Samples were observed for growth for 28 days. All cases were reviewed at a mean follow-up of 4.2 months (range, 1–12). Comparisons were made between infection cases and “clinically Insignificant” cases, with respect to: (1) risk factors, (3) symptoms/signs of infection, (2) active range-of-motion, (2) Simple Shoulder Test (SST) scores, values of (3) WBC, (4) ESR and (5) CRP, number of positive cultures for (6) P acnes and (7) other organisms and (8) subjective pre-operative, intra-operative and postoperative suspicion for occult infection.

Results: P. acnes was cultivated from 20 cases in 19 patients. Five cases (25%) were considered significant infections, while fifteen cases were considered “clinically insignificant”. The mean number of cultures positive for P. acnes was 1.7 (range, 1–4) per case. The mean active forward flexion (p=0.03) and internal rotation (p=0.03) was less for infection cases than for clinically Insignificant cases. Pre-operative ESR (p=0.04) and CRP (p=0.02) values were higher for infection cases. Infection cases had a higher number of positive intra-operative cultures for other organisms (p=0.04).

Conclusion: No combination of clinical parameters would reliably predict clinical infection in patients with positive intra-operative P. acnes cultures in revision shoulder surgery. In particular, positive P. acnes intra-operative cultures do not always represent true clinical infections. Pre-operative loss of range-of-motion, elevated ESR and CRP and positive intra-operative cultures for other organisms appear to correlate with true infections. The determination of a clinically significant infection needs to be based on the entirety of the clinical and laboratory information for each shoulder case.

Christina Goldstein Emil H. Schemitsch Mohit Bhandari George Mathew Brad Petrisor

Purpose: Identifying optimal treatment strategies in patients with traumatic foot and ankle injuries has been hampered by the variety of different measurement tools and lack of validation of generic and foot-specific functional measures. It remains plausible that the choice of functional outcome measure may influence our ability to accurately measure treatment effects. This prospective observational study aims to correlate the scores across six functional outcome measures in patients with traumatic foot and ankle injuries and to examine agreement of scores and patients’ subjective health status.

Method: Patients with traumatic foot or ankle injuries completed two generic, the SF-12 Health Survey and the Short Musculoskeletal Functional Assessment (SMFA), and four specific health outcome measures, the Foot Function Index (FFI), Foot and Ankle Ability Measure (FAAM), American Academy of Orthopedic Surgeons (AAOS) Foot and Ankle Questionnaire and the American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale, at a single follow-up visit. Raw scores were calculated and used to assign patients to a categorical functional level (excellent, very good, good, fair or poor). Agreement between the assignments was assessed and Pearson correlation co-efficients were calculated for each pair of outcome scores. Statistical significance was determined using an α of 0.05.

Results: 52 patients (mean age 43.3 ± 16.8 years) were enrolled at a mean follow-up of 15.5 months. All correlations except for that between the AOFAS ankle-hindfoot scale and the mental component of the SF-12 were statistically significant. The strongest correlations were found between the SMFA, FFI, AAOS Foot and Ankle Questionnaire and the FAAM. Despite significant correlation between scores and patients’ subjective functional outcome, there was minimal agreement between assigned categorical functional levels.

Conclusion: The high correlations between scores on the generic and foot-specific functional measures suggest that it is likely unnecessary to use more than one instrument when examining functional outcome in patients with traumatic foot and ankle injuries. Generic tools also appear to function as well as specific scores in this population. However, assignment of patients to a categorical functional level based on raw outcome scores must be performed with caution as the results obtained may not accurately reflect functional outcome.

Timothy R. Daniels Ellie Pinsker Taucha Inrig Kelly Warmington Dorcas Beaton

Purpose: The objective of this study is to compare items from patient-reported questionnaires measuring musculoskeletal outcomes with items generated by pre-and post-operative ankle arthrodesis and arthroplasty patients using the Patient-Specific Index (PSI-P). The International Classification of Functioning, Disability and Health (ICF) was used as an external reference.

Method: A literature review identified six questionnaires that assess lower extremity outcomes (AAOS, patient-reported portion of AOFAS, FFI, LEFS, SMFA, WOMAC). Surgical patients (n=142) from an orthopaedic surgeon’s practice completed the patient-selected items from PSI-P. Items from questionnaires and PSI-P were coded by three reviewers and linked to the ICF. The ICF is divided into four components (Body Functions and Structures, Activities and Participation, Environmental Factors, and Personal Factors) which are then further divided into second level categories. A higher number of second level categories would indicate a questionnaire that captures a broader range of experiences.

Results: Patient’s responses from PSI-P identified 690 meaningful concepts that were linked to 45 second level ICF categories. Most PSI-P responses fell into Activities and Participation (60.6%) and Body Functions and Body Structures (35.2%) including the second level categories Walking (19.1%), Pain (16.5%), and Recreation and Leisure (15.4%). There was no statistical difference between arthrodesis and arthroplasty patients nor between pre-operative versus postoperative patients in terms of the proportion of patient responses that fell into each ICF component. A total of 237 meaningful concepts were identified in the 6 questionnaires studied and linked to 38 second level ICF categories. Overall, SMFA addressed the most number of second level categories and had the closest proportion of Body Function (23.0%) and Activities and Participation (68.9%) concepts as compared to PSI-P. The patient-reported portion of AOFAS addressed the fewest categories. LEFS only contained items from Activities and Participation. AAOS was the only questionnaire to address the issue of ‘swelling’, though it represented 4.9% of all PSI-P responses.

Conclusion: Questionnaires differ largely in their content and no single questionnaire captured all of the concerns identified by PSI-P. This analysis will guide us in the development of a new and more comprehensive instrument for evaluating ankle outcomes following fusion or replacement.

Gerard Slobogean Alastair S.E. Younger Carlo A. Marra Kevin J. Wing Murray J. Penner Mark Glazebrook

Purpose: To describe the pre- and one-year post-operative preference-based, health related quality of life (health state values) among a cohort of subjects with end-stage ankle arthritis treated with total ankle arthroplasty or ankle arthrodesis. This short-term study is not intended to compare the efficacy of arthoplasty and arthrodesis.

Method: The Short-Form 36 (SF-36) was prospectively completed by subjects enrolled in the Canadian Orthopaedic Foot and Ankle Society Multicentered Ankle Arthritis Outcome Study between 2003 and 2005. Preference-based quality of life was assessed pre-operatively and at one-year post-procedure using health state values (HSVs) derived from the SF-36 transformation described by Brazier (SF-6D). The SF-6D scores are anchored at 1.0 (full health) and at 0 (death). Basic patient demographic and treatment information was also collected. The decision to perform arthroplasty or arthrodesis was made by the attending surgeon.

Results: Two hundred four of the 214 eligible subjects had complete preoperative SF-36 data to allow transformation to SF-6D values. One-year follow-up was available for 114 of the participants. The mean age at surgery of the included subjects was 58.9 +/− 13.3 years. Of the patients with one-year follow-up, 56% were male and 59% had received total ankle arthroplasty. These demographics did not differ from the original preoperative cohort. The mean SF-6D score among all subjects with end-stage ankle arthrosis was 0.66 (95% CI 0.65 – 0.68). At one-year, the mean HSVs of the total ankle arthroplasty and ankle arthrodesis groups were 0.73 (95% CI 0.71 – 0.76) and 0.73 (95% CI 0.70 – 0.75), respectively. The reported pre-operative scores describe health states below normative data for the US population (0.76 +/− 0.01 for females, ages 55–64).

Conclusion: These are the first available HSVs for a cohort of patients with end-stage ankle arthritis treated with total ankle arthroplasty or ankle arthrodesis. These data demonstrate an improvement in preference-based quality of life following ankle arthroplasty or arthrodesis. At one-year follow-up, patient reported HSVs approach age-matched US norms.

Andrea Veljkovic Jason Fong Allan Henigar David R. Wilson Michael J. Dunbar Mark Glazebrook

Purpose: Radiostereometric Analysis (RSA) is used to measure migration and inducible displacement (ID) of orthopedic implant devices to allow early prediction of implant failure (eg. Aseptic loosening). Total Ankle Arthroplasty (TAA) is used for the treatment of end-stage ankle arthritis. First generation TAA implant have meet with widespread failures while some second generation TAA implants are showing improved results. In this study RSA is used to evaluate the biomechanical properties of a new third generation TAA implant in an attempt to set a standard for the biomechanical evaluation on TAA implants in-vivo.

Method: Patients undergoing TAA were enrolled consecutively (n=12; 7 males; mean age=59 years; mean BMI=29) and had 8 markers (0.08mm) inserted in both the tibia and talus during surgery. Standing, weight-bearing RSA exams were performed at 3 and 6 months and compared to concurrent supine exams to determine component ID.

Results: For tibial components: at six months the components had translated posteriorly (0.3mm±0.5) and proximally (0.5mm±0.2), tilted into varus (0.5°±1.3), and tilted posteriorly (0.4°±0.8). The magnitudes of ID for the tibial components were moderate (mean < 0.2mm and 0.5°, standard deviation < 0.3mm and 2.2° in each direction). For talar components: at six months the components had translated distally (0.28mm±0.35), rotated internally (0.21°±1.32) and tilted posteriorly (0.15°±0.90). There was varus/valgus tilt measured in the talar components but there was no consistent direction of migration (0.03°±1.4). At six months the magnitudes of ID for the talar components were small (mean < 0.1mm and 0.25°, standard deviation < 0.2mm and 0.6° in each direction).

Conclusion: An RSA methodology has been established to predict stability.

Peter Copithorne Timothy R. Daniels Mark Glazebrook

Purpose: For patients with moderate to severe hallux valgus with increased intermetatarsal angle, correction with a proximal first metatarsal osteotomy is indicated. The purpose of this study is to compare the opening-wedge osteotomy of the proximal first metatarsal the proximal chevron osteotomy in the treatment of moderate to severe hallux valgus with increased intermetatarsal angle.

Method: This prospective, randomized, multi-centered study is being conducted at three centers in Canada. Approximately 75 adult patients with hallux valgus are being randomized to either the proximal metatarsal opening-wedge osteotomy with plate fixation or the proximal chevron osteotomy. Patient functional scores using the SF-36, American Orthopaedic Foot and Ankle Society (AOFAS) forefoot metatarsophalangeal inter-phalangeal score and Visual Analogue Scale (VAS) for pain, activity & patient satisfaction, are assessed prior to surgery and 3, 6, 12 and 24 months. Surgeon preference is being evaluated based on a questionnaire and actual surgical times. Radiologic measurements (inter-metatarsal angle correction, hallux valgus angle correction, sagital talus-first metatarsal (Meary’s) angle, metatarsal length and union) will also be assessed.

Results: Preliminary results demonstrate that patients who undergo the opening-wedge osteotomy have less pain at 3 months (ave. VAS pain reduction 2.9, SE±1.0) than those with the chevron (ave. VAS pain reduction 2.4, SE±1.2). VAS for activity demonstrates greater improvements with the chevron osteotomy at 3 months (0.8, SE±0.8) versus the opening-wedge (0.1, SE±1.0). AOFAS scores improve on average 18.3 (SE±8.6) with the opening wedge compared to 20.8 (SE±7.4) with the chevron at 3 months. Average hallux valgus angle correction for opening-wedge and chevron osteotomies are 11.0 degrees (SE±2.5) and 19.0 degrees (SE±3.1) respectfully. Average intermetatarsal angle correction for opening-wedge and chevron osteotomies are 6.5 (SE±1.3) and 4.3 (SE±1.7) respectfully. Both procedures are effective at maintaining metatarsal length. The opening-wedge osteotomy takes on average 60.9 minutes (SE±3.9) to complete compared to 69.1 minutes (SE±5.1) for the chevron ostetotomy. Surgeon response to the new opening-wedge osteotomy is favorable.

Conclusion: Opening-wedge and proximal chevron osteotomies have comparable pain, function and radiographic outcomes. Opening wedge osteotomy is technically less demanding and requires less surgical time.

Stéphane Leduc Michael P. Clare Scott Swanson Arthur K. Walling

Purpose: Insertional calcific Achilles tendinosis is a painful, frequently disabling, condition. The longitudinal and radial alignment of the angiosomes of the posterior region of the leg makes a straight posterior midline approach logical. The safety of the posterior midline approach and the outcome of a central tendon splitting approach associated with a Strayer procedure to treat this condition was evaluated.

Method: A retrospective review of a consecutive cohort of a single surgeon was performed. All patients had failed conservative treatment and all patients were primary cases. Forty-seven patients (48 heels) were treated over a 11-year period for chronic insertional Achilles tendinosis. All patients underwent a midline posterior splitting approach, debridment of the bursae, resection of the haglund deformity, partial Achilles detachment, debridement, reinsertion with bone anchor associated with a proximal gatrocnemius recession (strayer procedure) through a second midline incision. The average age was 59 years old (39–75), co-morbidities included four smokers and one diabetic patient. The average followup was 54 months (15–144). All patients answered pre-op and latest follow up AOFAS questionnaire, satisfaction rate and complications were reviewed.

Results: Satisfaction rate was 100%. AOFAS score improved significantly from 59 (36–80) preop to 97 (90–100) at the latest follow-up. Complications included one superficial infection and one sural nerve paresthesia. There were no major complications.

Conclusion: Achilles insertional tendinopathy treated by a posterior midline approach is a safe and reliable procedure. The procedure was associated with high patient satisfaction rate and excellent outcome.

Benoit Benoit Stéphanie Grenier G. Yves Laflamme Dominique Rouleau Stéphane Leduc

Purpose: Lors de la réduction chirurgicale des fractures de la cheville avec instabilité syndesmotique, le chirurgien se fie généralement sur les vues de mortaise et antéro-postérieure. Toutefois, une subluxation ou luxation antérieure du péroné par rapport au tibia distal peu survenir et passer inaperçu (trois exemples cliniques prouvés par CT Scan post-opératoire), spécialement lors de la pose de vis syndesmotique(s). La présente étude a pour but d’établir la relation radiologique précise sur une vue latérale fluoroscopique entre les tibia et péroné distaux qui permettra au chirurgien de confirmer en peropératoire que l’articulation tibio-péronière distale est bel et bien réduite.

Method: Les chevilles normales de trente volontaires sans antécédent de traumatisme ou de maladie de la cheville ont été imagées sous une vue latérale fluoroscopique parfaite, avec un Mini C-Arm. Les images ont été analysées et comparées entre elle afin d’établir une relation radiologique fiable et reproductible entre le tibia et le péroné distaux.

Results: Dans les trente cas, il y avait intersection du milieu de la cicatrice physaire et du cortex antérieur du péroné. Cette relation a été trouvée statistiquement significative.

Conclusion: La réduction chirurgicale parfaite de l’articulation tibio-péronière distale peut être confirmée avec une vue latérale fluoroscopique de la cheville. Le cortex antérieur du péroné doit toucher le milieu de la cicatrice physaire.

Vishal Upadhyay Ajay Sahu N. Harshavardena Charalambos P. Charalambous Richard Hartley

Purpose: The aim of this study was to compare the results and length of stay of patients of early ankle fracture fixation with conventional fixation in a busy District General Hospital in UK.

Method: A retrospective study was conducted using data from case records, electronic patient record, clinical coding information, clinic letters and Picture Archiving and Communications System (PACS). Two hundred patients who underwent ankle fracture fixation from July 2004 to June 2005 were included. We looked into age, place of living, Weber classification, mechanism of injury, comorbidities especially diabetes and peripheral vascular disease, addictions mainly smoking, whether patient was anticoagulated, delay for theatre with reasons, length of stay in hospital and complications if any. Other things to looked at were, overlying skin condition, the amount of swelling at the time of presentation to A& E, associated ankle dislocation or talar shift needing reduction, injury types-open or closed or with associated neuro-vascular injury. In-operative management – what method was used ie malleolar screws, diastasis screw, fibular plating, calcaneotalotibial nail or external fixater etc.

Results: In the 12-month retrospective review, there were 200 ankle fractures that required surgical intervention. Only twenty-two of these had surgery within 12 hours (mean length of stay, 3.3 days), and sixty-seven of these had surgery within 48 hours (mean length of stay, 4.9 days), and 111 had surgery after 48 hours (mean length of stay, 9.4 days). Finally we calculated the cost (784 bed days – £235 thousands) incurred to the trust in terms of extra bed occupancy and treating the complications as a result of wait.

Conclusion: This study shows that early operative intervention for ankle fractures reduces the length of hospital stay. Intensive physiotherapy and co-ordinated discharge planning are also essential ingredients for early discharge. We want to emphasise on the ‘Window of Opportunity’ ie initial 12 hours to fix ankle fractures to decrease overall morbidity and cost.

Robert B. Bourne Bert Chesworth Aileen Davis Nizar N. Mahomed Kory D. Charron

Purpose: The purpose of this study was to determine why some TKR patients are satisfied and others are dissatisfied.

Method: 2,481 primary TKR patients who had completed a decision date WOMAC were randomly identified within the Ontario Joint Replacement Registry (OJRR) database. One year post-operatively, these patients were mailed a survey to determine satisfaction/expectations, willingness to undergo surgery again, Jaeschke self-reported clinical improvement, WOMAC scores and complications. The satisfied and not satisfied patient groups were identified, statistical analysis employed to determine variables that individually affect satisfaction and logistic regression used to identify significant factors which might lead to patient dissatisfaction.

Results: Only 70% of primary TKR patients felt that their expectations had been met and 15% reported that they had no expectations. Only 81% of patients reported that they were satisfied with their TKR. When asked whether they would have their surgery again, 96% of the satisfied patients reported that they would do so as compared to only 63% in the dissatisfied group (p< 0.0001). Using the Jaeschke self-reported clinical improvement scale, 87% of TKR patients reported that they were improved, but only 75% reported that they were a good, great or a very great deal improved. There was a high correlation with the WOMAC change score and the Jaeschke self-reported improvement and willingness to undergo surgery again questions. Significant differences were found between the satisfied and dissatisfied TKR patients in terms of a pre-operative WOMAC score of < 20 (p< 0.004), the WOMAC change score (p< 0.0001), expectations (p< 0.0001), complications (p< 0.0001), age (p< 0.002), referral status (p< 0.0005), living alone (p< 0.01) and comorbidities (p< 0.05). Logistic regression suggested that the most important predictive factors were a pre-operative WOMAC < 20 (p< 004), the WOMAC change score (p< 0.0001), expectations met (p< 0.0001) and complications (p< 0.0001).

Conclusion: Only one in five primary TKR patients are satisfied with their operative procedure. Significant risk factors for patient dissatisfaction after primary TKR include a pre-operative WOMAC < 20, a WOMAC change score of less than 33 points, expectations that were not met or a complication.

Pascal-André Vendittoli Melissa Collins Muthu Ganapathi Martin Lavigne

Purpose: The goal of this study is to compare patients’ perception of their hip or knee joint following joint replacement surgery.

Method: A total of 357 patients who underwent hip or knee joint surgery were included in the study. Of the patients who had knee replacement surgery, 46 had unicompartmental knee replacement (UKR) and 119 had total knee replacement (TKR). In the group of patients who had hip replacement surgery, 98 underwent hip resurfacing (SRA) and 97 had total hip replacements (THR). The perception patients had of their replaced articulation as well as functional outcome scores such as the WOMAC and SF-36 were measured at one year post-surgery and compared between the four groups.

Results: Although global satisfaction and clinical outcome scores were excellent in all four groups, WOMAC scores at 1–2 year follow-up were significantly different between hip or knee replacement surgery (p< 0.0001). Also, the perception that patients had of their reconstructed joint was significantly different between the hip and knee groups (p< 0.001). Half of patients from the hip group considered their replaced hip “as a natural joint” and 76% considered their joint as having no functional limitations compared to only 19% and 39% respectively for the knee group. Of patients with knee joint surgery, 14% (20/165) considered their joint as “artificial with important limitations” as opposed to only 1% (2/195) of those who had hip joint surgery. There were no significant differences in Womac scores or perception when comparing TKR and UKR or THR and SRA patients. Perception was strongly correlated to Womac scores for all four groups (R2=0.951).

Conclusion: Hip and knee joint replacement surgery are recognized as highly effective medical interventions in terms of cost/benefit ratio in current medical practice. It is remarkable to see that replacement of each of these articulations can yield vastly different results in terms of patient function, perception and satisfaction. From this study, it is clear that research in prosthetic development and surgical techniques should be focused on the interventions such as knee joint replacement, which are not yet capable of offering both a high level of function and satisfaction to patients.

Vishal Upadhyay Ravi H. Mahajan Ajay Sahu Usman Butt Amir Khan Rakesh B. Dalal

Purpose: To assess moderate-term outcomes of silastic joint replacements of the first metatarsophalangeal joint.

Method: The thirty-two patients (37 feet) that had silastic implants inserted were reviewed at an average of 2 years and 4 months (ranging 7 months to 5 years and 4 months). The mean patient age was 63 years. These patients answered a subjective questionnaire, had their feet examined clinically and radiographically and a pre-operative and post-operative AOFAS score was calculated for each.

Results: The follow-up assessment revealed that every patient described that their pain had decreased after surgery and 17 feet (46%) were completely pain free. There was a significant improvement in patients’ subjective pain scores after surgery (t value = < 0.0001). Pre-operatively, the mean pain score for all 37 feet was 8.14, whereas post-operative the mean pain score was 1.32. The mean AOFAS score before surgery was 39.97. This increased to a mean score of 87.40 after surgery (P = < 0.0001). This again is a significant improvement. No patient was dissatisfied with the outcome with their surgery.

Conclusion: These moderate term results are encouraging, with good subjective and objective results. However, long-term follow-up will be required to assess the longevity of this implant.

Kevin Willits Nicholas G.H. Mohtadi Crystal Kean Dianne Bryant Annunziato Amendola

Purpose: The purpose of this randomised controlled trial was to compare outcomes of operative and non-operative management of Achilles tendon ruptures.

Method: Patients with acute complete Achilles tendon ruptures were randomised to receive open suture repair followed by graduated rehabilitation or graduated rehabilitation alone. The primary outcome measure was re-rupture rate. Assessments at three and six months, and one and two years included a modified Leppelhati score (no strength data), range of motion, calf circumference, and isokinetic strength at one and two years. We report the two year findings.

Results: Two centres randomized 145 patients (118 males and 27 females), mean age 40.9±8.8 years (22.5 – 67.2) to operative (n=73) and non-operative (n=72) treatment. Fourteen were lost to follow-up. Re-rupture occurred in three patients in both groups. The mean modified Lep-pelhati score (out of 85) was 78.2±7.7 in the operative group and 79.7±7.0 in the non-operative group, which was not significant (−1.5 95%CI −6.4 to 3.5, p=0.55). Mean side-to-side difference in plantar flexion and calf-circumference in the operative group was −2.0±3.2° and −1.4±1.2cm, and in the non-operative group −0.9±3.0°and −1.6±1.8cm respectively. Mean isokinetic plantar flexion strength was 62.4±24.2 for the operative and 56.7±19.3 for the non-operative group, which was not significant (5.7, 95%CI −3.1 to 14.5, p=0.20). There were a greater number of serious adverse events in the operative group, including pulmonary embolus in one patient, deep vein thrombosis in one and deep infections requiring irrigation and debridement in three.

Conclusion: This study suggests that non-operative management of Achilles tendon ruptures utilizing an accelerated rehabilitation programme may produce comparable results with fewer adverse events.

Steven J.M. MacDonald Kory D. Charron Douglas Naudie Richard W. McCalden University Hospital Robert B. Bourne Cecil H. Rorabeck

Purpose: The growing trend of morbidly obese (BMI 40+) patients requiring a total joint replacement is becoming major concern in total knee Arthroplasty (TKA). The purpose of this study was to investigate the affects that BMI may have on implant longevity and clinical patient outcome using historical patient data.

Method: A consecutive cohort of 3083 TKA’s in 2048 patients since 1995 (minimum 2 years follow-up) were evaluated. Pre-operative scores, latest scores, and change in clinical outcome scores (KSCRS, SF12, WOMAC) were analyzed using ANOVA and Kaplan-Meier (K-M) survivorship was determined.

Results: K-M cumulative survival at 10 years by BMI group was 0.951±0.033 for Normal and Underweight (< 25, n=277), 0.944±0.024 for Overweight (25–29.9, n=915), 0.882±0.032 for Obese (30–39.9, n=1460) and 0.843±0.076 for Morbidly Obese (40+, n=352). Cumulative revision rates were 1.8% for Normal and Underweight, 1.9% for Overweight, 2.9% for Obese and 2.8% for Morbidly Obese. All pre-operative clinical scores were significantly different between the Morbidly Obese and all other BMI groups (p< 0.05), with the non-morbidly obese having higher scores in all cases. Significant difference was found in the change in WOMAC domain scores and the KSCRS knee score (p< 0.05) between the morbidly obese group and all other BMI groups, with the morbidly obese having the greatest improvement in all domains.

Conclusion: The morbidly obese patient cohort (BMI > 40) undergoing TKA demonstrated the most significant improvement in clinical outcome scores; however also had the lowest cumulative 10 year survivorship. This risk/benefit information is important in pre-operative discussions with this challenging, and increasingly prevalent, patient population.

Rajiv Gandhi Mark Takahashi Khalid Syed J Roderick Davey Nizar N. Mahomed

Purpose: Synovial fluid (SF) leptin has been shown to have an association with cartilage degeneration. Our objective was to examine the relationship between different measures of body habitus and SF leptin levels in an end stage knee osteoarthritis (OA) population.

Method: Sixty consecutive patients with knee OA were surveyed prior to surgery for demographic data. Body habitus was assessed with the body mass index (BMI), waist circumference (WC) and waist-hip ratio (WHR). SF and serum samples were analyzed for leptin and adiponectin using specific ELISA. Non-parametric correlations and linear regression modeling was used to identify the relationship between the measures of body habitus and SF leptin levels.

Results: Females had greater levels of leptin than males in both the serum and SF. Significant correlations were found between SF leptin levels and BMI and WC (R2 0.44 and 0.38 respectively, p< 0.05). Regression modeling showed that female gender and WC were independent predictors of a greater SF leptin level independent of age, BMI, and presence of diabetes.(p< 0.05)

Conclusion: WC may be a more accurate measure of body habitus than BMI in the relationship between the metabolic effects of adipose tissue and OA.

Linda J. Woodhouse Danielle Petruccelli Joanne Wright Wade Elliott Nancy Toffolo Stephen Patton Sampa Samanta Arlene Sardo Donna MacMillan Gail Johnson Christine Anderson William Evans

Purpose: Reducing wait times for total hip (THA) or knee (TKA) joint arthroplasty is a Canadian health care priority. Models that maximise the capacity of advanced practice clinicians (nurses, physical therapists, sports medicine specialists) have been established to streamline care. Hospitals across the Hamilton Niagara Haldimand Brant Local Health Integration Network in Ontario collaborated to establish a Regional Joint Assessment Centre (RJAC). This study was designed to profile patients deemed suitable for surgical review, and to examine wait times for THA or TKA in RJAC patients compared to those referred directly to an orthopaedic surgeon’s office.

Method: Patients referred to the RJAC between July 2007 and August 2008 with knee or hip OA were included. Self-reported function was evaluated using the Oxford Hip and Knee Score that is scored out of 60 (higher scores reflect greater disability). Time to surgery was measured as the number of days from initial review to surgery. Group one consisted of patients that were referred to the RJAC while group two was comprised of patients who were referred directly to a surgeon’s office. Patient characteristics were examined using univariate analyses. Independent t-tests were used to examine between group differences.

Results: One hundred thirty-six patients (mean±sd: 68±2 years, body mass index 31±6 kg/m2, 83 females) with 150 hip and/or knee joint problems were reviewed in the RJAC. Of those, only 33% (45/136 patients) were deemed suitable for surgical review. Self-reported function (Oxford Scores) in the group requiring surgical review was significantly worse (40±7, p=0.03) than in those patients deemed unsuitable for surgical review (37±9). The RJAC group waited on average 130 days for THA and 129 days for TKA (below the provincial target of 182 days) while those referred directly to the surgeons’ offices waited significantly longer (194 days for THA and 206 days for TKA, p< 0.001).

Conclusion: Patients with hip and knee OA who require surgical review have worse self-reported function than those triaged to conservative care. Wait times for THA or TKA were significantly shorter for patients referred to the RJAC under the new model of care than for those referred directly to an orthopaedic surgeon’s office.

David Backstein Christopher Peskun Ian Mayne Harsha Malempati Yona Kosashvili Vir Sennik Allan E. Gross

Purpose: Single anesthetic bilateral total knee arthroplasty (SABTKA) is a controversial procedure with a questionable safety profile. The purpose of this study was to determine if specific, individual preoperative medical co-morbidities can predict perioperative complications in patients undergoing SABTKA.

Method: The records of all SABTKA performed between 1997 and 2007 at 1 large community hospital and 1 academic, university hospital were retrospectively reviewed. Complete demographic data, preoperative co-morbidities (cardiovascular disease, COPD, diabetes, and hypertension), and perioperative complications for 156 patients were collected and analyzed using logistic multivariate regression analysis. Comparison was made to an age, gender, and co-morbidity matched cohort of patients treated with unilateral TKA.

Results: In the SABTKA group only 11% of patients had a preoperative history of cardiovascular disease yet 89% of all post operative myocardial infarctions (MI) occurred in this population (p< 0.001, Odds Ratio 57.8). Cardiovascular disease also predicted need for admission to ICU (p< 0.001, Odds Ratio 50.8), and number of days spent in the ICU (p< 0.001). In those patients without preoperative cardiovascular disease or COPD the rate of MI was only 0.64%. All differences were significant when compared to the matched unilateral TKA cohort. Age, gender, diabetes, and hypertension did not predict perioperative complications in the SABTKA cohort.

Conclusion: The literature indicates there are certain populations of patients at higher risk for perioperative complications after SABTKA. This study clearly identifies a subpopulation of patients that have cardiovascular disease and are at an unacceptably high risk of perioperative MI. Cardiovascular disease should likely be considered an absolute contraindication to SABTKA.

Douglas Naudie Dianne Bryant Trevor Birmingham Ian Jones J. Robert Giffin

Purpose: Medial compartment osteoarthritis (OA) is the most common primary osteoarthritis of the knee, but the treatment of this disease in young patients remains controversial. High tibial osteotomy (HTO), medial unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are all viable options. Gait analysis is one tool available to clinically assess knee kinematics, and may prove to be a good way of predicting functional outcomes of these different surgical procedures. The purpose of this study was to compare the knee kinematics, function, and quality of life of patients that underwent either a medial opening wedge HTO, UKA, or TKA for primary medial compartment OA.

Method: A matched prospective cohort study of patients between the ages of 45 and 65 who had undergone an HTO, UKA, or TKA for primary medial compartment knee OA was undertaken over a 3-year period. Primary outcome measures were gait variables, namely knee adduction moments, as measured through gait analysis. Secondary measures included quality of life (WOMAC), functional performance tests (six minute walk and timed-up-and-go), self-reported functional ability (LEFS), and general health (SF-36). Gait and functional performance tests were evaluated preoperatively and at 6, 12, and 24 months postoperatively. Self-reported quality of life, function and general health were assessed preoperatively and at 3, 6, 12, and 24 months post-operatively.

Results: Twenty HTOs, 19 medial UKAs, and 17 TKAs were matched for Kellgren-Lawrence grade of medial OA, age at surgery, and body mass index. Significant differences were observed between the three groups in step length and peak adduction moments at 24 months. Significant differences were observed in preoperative WOMAC pain and function scores, KOOS pain scores, and LEFS, but no significantly different outcome measures were observed postoperatively. Lateral Black-burne-Peel and modified Insall-Salvati ratios were the only significant radiographic differences observed between groups at 24 months.

Conclusion: To our knowledge, no gait analysis study exists comparing the medial opening wedge HTO to UKA or TKA. The results of this study suggest that most gait variables except step length and knee adduction moments are similar between groups. Moreover, except for patellar height, there were no major functional or radiographic differences between these groups.

Camilo Resterpo Javad Parvizi Peter F. Sharkey Aidin Eslam Pour Craig T. Haytmanek Nathan Roberts Richard H. Rothman

Purpose: Recently an orthopedic manufacturer has introduced a gender specific knee design implying that there is a substantial anatomical difference between the genders. If such concept is true then TKA prosthesis implanted in the female population over the last decades, by definition, must have suboptimal outcome when compared to the male patients. The purpose of this study was to examine the functional outcome, the incidence of complications, and the need for revision between the two genders receiving the same knee design.

Method: The study selected a matched group of 150 men and 250 women undergoing TKA at our instituion. The patients were matched for age, BMI, pre-op diagnosis, comorbidities, race, mode of fixation, and the type of implant. Other demographic, surgical, and medical factors between the two genders were similar. Both pre-op and post-op functional scores were compared between the two groups. Pre-op and post-op radiographic images were assessed for implant fit.

Results: There was a significant improvement in functional outcome as measured by Knee Society score, WOMAC, and SF-36 for all patients. The improvement in functional outcome was not different between the two groups. The incidence of complications, reoperations, and need for revision between the two genders was also not significantly different.

Conclusion: Total knee arthroplasty continues to be an effective surgical procedure. Both genders appear to enjoy relief of pain and improvement of function equally. Based on this retrospective study the use of non-gender specific knee prosthesis did not seem to result in suboptimal outcome in female patients. There appears to be little merit in introduction of gender specific knee designs when previous non-gender specific prosthesis appeared to function well in both genders.

Geoffrey Dervin Holly Evans Susan Madden Peter R. Thurston

Purpose: Unicompartmental replacement for medial compartment arthrosis of the knee has become popular with eligible patients because of the shortened recovery time, decreased tissue damage and easier future revision. Contemporary multimodal anesthesia has added the potential to safely perform this as outpatient surgery reducing inpatient bed burden. We describe our initial pilot experience with this approach.

Method: The first 25 patients who fulfilled the criteria developed underwent same day surgery for unicompart-mental arthroplasty for medial (19) or lateral (3) compartment replacement with either the Oxford knee (20) or the Uniglide (2). All patients were treated with an indwelling femoral nerve catheter supplied by Ropivacaine through a constant release pump (Stryker) which was discontinued at 48 hours. Home care support was made available in first 72 hours by way of RN and physiotherapy visits and mandatory use of walker or crutches for the first 48 hours.

Results: Patients in this cohort were universally very satisfied with the model of postop care as described and particularly pleased to avoid a hospital stay. Eighty percent of those who were offered this model chose it. The use of narcotic oral medication was consistently about 50% less than that observed to similar inpatients treated without catheter, and eight patients had complete opioid sparing experience. There were no complications related to the catheter, in particular serious falls or longer term neurologic sequelae. The clinical results were very good and equal to those who were in patients.

Conclusion: Outpatient unicompartmental replacement can be performed safely recognizing the decreased surgical trauma and pain stimuli associated with UKR and a relatively younger and healthier cohort screened for this alternative. These patients are amongst the most satisfied with their perioperative course and all would do the same again if given the chance. Other models of analgesia could be considered, though the catheter does seem to have a large opioid sparing effect that likely contributed to patient well being and satisfaction.

Kelly Lefaivre Adam J. Starr Brady P. Barker Stephen J. Overturf Charles M. Reinert

Purpose: To describe operative experience and reductions of pelvic ring fractures treated with a novel pelvic reduction frame.

Method: All patients with displaced pelvic ring disruptions treated with the pelvic reduction frame were included. The series includes 35 patients, with 34 acute fractures and one malunion. Pre-operative and immediate post-operative radiographs were reviewed, and maximal displacement measured using two reproducible methods. Procedure and injury data were also recorded.

Results: In our series of 35 patients, we had 19 vertical shear fractures and 16 compression injuries. Mean age was 33.5 + 2.4, and mean delay to surgery was 4.7 + 0.6 days. Mean operative time in isolated procedures was 103.4 + 6.5 minutes. All but one patient had iliosacral screws placed, 18 had anterior column screws, six had symphysis plates and 12 had anterior external fixators. Maximum horizontal or vertical displacement was improved from 30.8 + 2.7 mm to 7.1 + 0.7 mm. Diameter asymmetry as measured on the AP view was improved form 26.4 + 2.7 mm to 5.2 + 0.7 mm. Very good, good or fair reduction was obtained in all acute cases. There was no statistically significant impact of obesity, fracture type or delay to surgery on quality of reduction (p> 0.05).

Conclusion: This novel pelvic reduction frame is a powerful tool in the effective reduction and fixation of displaced acute pelvic ring disruptions.

Robert L. Barrack R. Stephen J. Burnett C. Lowry Barnes Derk Miller John C. Clohisy William J. Maloney

Purpose: A study was undertaken to determine the current prevalence of revisions of total knee arthroplasty (TKA) following minimal incision surgery (MIS) and to compare revisions of MIS TKA procedures to revisions of TKA performed following a standard surgical approach.

Method: A consecutive series of revision TKA performed at three centers by five surgeons over a three year time period was reviewed. Revisions performed for infection and re-revisions were excluded. Review of clinical and radiographic data determined incision type, gender, age, time to revision, and primary diagnosis at time of revision.

Results: Two hundred and thirty-seven first time revision TKAs were performed of which 44 (18.6%) had been a MIS primary TKA and 193 (81.4%) had been a standard primary TKA. Patients with MIS were younger (62.1 years versus 66.2 years, p=.02). There was a trend towards a higher percentage of females in the MIS group (75% versus 63%), although this difference was not significant (p=0.12). Most striking was the difference in time to revision which was significantly shorter for the MIS group (14.8 months versus 80 months, p< .001). The MIS group was much more likely to fail at < 12 months (37% versus 5%, p< .001) and at < 24 months (81% versus 22%, p< .001).

Conclusion: MIS TKA accounted for a substantial percentage of revision TKA in recent years at these centers. The high prevalence of MIS failures occurring within 24 months is disturbing and warrants further investigation.

Kelly Lefaivre Jeffrey R. Padalecki Adam J. Starr

Purpose: To provide a CT-based description of the anatomic specifics of LC-1 pelvic ring disruptionsand to describe injury severity to other body systems, and their correlation with fracture anatomy.

Method: We identified a consecutive series of 100 patients with Young and Burgess LC-1 pelvic ring disruptions. The CT scan was reviewed for each patient. Sixteen categories were reviewed for each patient. Sacral fractures were graded based on severity. The age, ISS, and six categories of AIS were recorded for each patient. A statistical analysis was performed to test the associations between fracture characteristics and injury severity.

Results: All patients but three had one or more rami fractures, and all but two had a sacral fracture. Of the 98 anterior sacral injuries, there were nine (9.2%) buckles, 39 (39.8%) simple fractures, and 50 (51.0%) comminuted fractures. Of these 98 anterior sacral injuries, 47 (48.0%) were complete, passing through the sacrum and exiting the posterior cortex. Increasing severity of anterior sacrum fracture was associated with the presence of a complete sacral fracture (p value < 0.0001). Of the 98 sacral fractures, 50 (50.0%) were Denis type I, 41 (41.8%) Denis type II, and 7 (7.1%) Denis type III. Higher Denis types had higher likelihood of complete fractures of the sacrum (p value < 0.0001). There was a significant association between the presence of a comminuted rami fracture and a complete sacrum injury (p = 0.003), and a trend to higher rates in Nakatani two superior rami fractures (p = 0.169). There was a trend to higher mean ISS scores (p = 0.2287), and significantly higher abdominal AIS scores (p = 0.0014), in those with a complete sacral fracture. Those with comminuted and complete sacral fractures were more likely to be symptomatic and require posterior ring stabilization (p-value 0.003 and 0.043 respectively).

Conclusion: LC-1 fractures of the pelvic ring represent a spectrum of injuries, with a large proportion having complete disruption of the sacrum. This complete injury of the sacrum is predicted by Denis type, severity of anterior ring disruption, Abdominal AIS, and potentially location of rami fracture and ISS. CT scanning best defines these injuries.

Rahul Vaidya Fredrick Tonnos Robert Colen Anil Sethi

Purpose: The purpose of this paper is to present a novel technique of anterior fixation of unstable pelvic fractures which is minimally invasive, biomechanically suitable, easy to apply, and uses readily available spinal implants.

Method: Eighteen consecutive patients with unstable pelvic fractures (AO type A-12 patients and type B-6 patients) underwent stabilization using the novel technique of fixation and were included in the study. Two trauma trained orthopedic surgeons performed all the procedures. All patients were evaluated clinically and with imaging studies that included antero-posterior, inlet and outlet radiographs and a CT scan. At surgery the posterior instability was addressed first with iliosacral screw fixation following reduction of the fracture in a standard fashion. A 2–3cm longitudinal incision was then made over the anterior inferior iliac spine bilaterally to obtain a starting point in the supra acetabular region. Pedicle screws of size 7mm or 8mm x 80mm (Synthes Spine Paoli, USA) were then placed in the supra-acetabular position under fluoroscopic guidance. A pre-contoured 6mm titanium rod with a bow was then tunneled subcutaneously to connect the screws. Care was taken to place the rod just below the lower abdominal crease to prevent pressure on the bowel or vascular structures. The implants were compressed using standard compressors and C-rings. Patients were followed until the pelvis fracture healed as documented on X-rays and clinical exam.

Results: Patients were followed for a minimum 6 months (range 6–12 mo). All patients healed by 3 months (similar to our prior experience using other methods). Complications included: 2 deaths in poly trauma patients unrelated to the pelvic procedure; 2 patients with transient lateral femoral cutaneous nerve palsy (one on each side), and one early implant failure due to a surgical technical error that was re-operated the next day.

Conclusion: Disruptions of the pelvic ring are complex injuries and should be managed on a case specific basis. By employing the established principles of supra-acetabular fixation, this technique allows for minimally invasive, definitive internal anterior fixation. The potential complications of pin tract infection and a cumbersome external appliance associated with external fixation are avoided with this technique and better patient acceptance is achieved.

Kajsa Duke G. Yves Laflamme Yvan Petit

Purpose: Greater trochanter reattachment is frequently accomplished using cable grip type systems. There is a relatively high failure rate for these systems, the mechanisms of which are unclear. One possible source of instability could be femoral neck cut location. Another concern is the effect of variability in cable tension. The objective is to create a femur implant model which allows for variation in cable tension, common muscle forces and the placement of the femoral neck cut in order to analyse trochanter fragment fixation.

Method: A finite element model (FEM) of a femur with simulated greater trochanter osteotomy (30°) was combined with the femoral component of a hip prosthesis and a greater trochanter reattachment system with 4 cables (Cable-Ready®, Zimmer). A total of 18 simulations were modeled in a full factorial design using three independent variables; cable tightening (178N, 356 N and 534 N), muscle forces (rest, walking and stair climbing) and femoral neck cut (10 mm and 15 mm above the lesser trochanter). Displacement of the fragment, in terms of both gap and shear components, as well, stress in the bone were investigated.

Results: The location of the femoral neck cut reduced contact surface area by 20% and had the largest influence on displacement (0.24 mm). Pivoting of the fragment was observed with a maximum gap (0.38 mm) and maximum total displacement (0.41 mm) at the bottom of the fragment. This was observed during stair climbing, while the cables were tightened to 177.9 N and with the femoral neck cut at 10 mm. Increased tightening of the cables provided no significant reduction in fragment displacement. However, higher cable tension significantly increased the stress in the bone (8 MPa and 26 MPa for cable tension of 178 N and 534 N respectively).

Conclusion: Placement of the femoral neck cut closer to the lesser trochanter significantly increased fragment displacement. Preservation of the contact surface area is recommended. Excessive cable tightening did not reduce fragment movement and only exacerbated bone stress. Caution must be used to not over tighten the cables. This model can be used to test and compare the performance of new implant designs.

David Barei Michael Gardner Sean Nork Stephen Benirschke

Purpose: Pilon fractures demonstrate complex osseous and soft tissue injury. Protocols involving immediate tibial reduction and external fixation, with or without fibular fixation, then delayed definitive fixation result in decreased complications. Our purpose was to evaluate the treatment course of pilon fractures provisionally stabilised at outside institutions and subsequently transferred, focusing on the incidence and reasons for revision procedures, and subsequent complication rates.

Method: An institutional trauma database was retrospectively reviewed, demonstrating 668 pilon fractures treated at our institution between 2000–2007. Of these, 39 patients with 42 fractures had a temporising surgical procedure prior to referral. Demographics, injury characteristics, reason for revision, and subsequent complications were determined. Clinical follow-up averaged 60 weeks (range, 1 to 281).

Results: Mean age was 41 years (range, 18–78). Twenty-two fractures (52%) were open; 38 (90%) demonstrated a fractured fibula. Referral occurred an average of 5.8 days (range, 1–20) after initial stabilization. Pre-transfer fixation was revised in 40 fractures (95%). Reasons for revision included tibial malreduction (33 fractures, 83%), fibular malreduction (4 fractures, 10%), pins in the proposed incision (5 fractures, 13%), or loose pins (3 fractures, 8%). Of the 34 fractures with distal pins, 24 (71%) required revision for pin malposition, loosening, drainage, talar placement, or extraosseous placement. Late complications occurred in 14 fractures (33%), including deep infection in 10 (24%), and non-union in 3 (7%). Twenty-three patients (55%) required additional procedures following definitive fixation, including 9 soft tissue coverage procedures and 3 amputations.

Conclusion: The majority of patients with pilon fractures treated with provisional stabilisation followed by referral to our institution required revision prior to definitive fixation. This resulted in many avoidable additional procedures, and a higher complication rate than recent contemporary controls. The authors recommend that, when possible, the initial and definitive management of these injuries be performed at the accepting institution.

Richard Jenkinson Marcella A. Maathuis Bill Ristevski Dan Omoto David J.G. Stephen Hans J. Kreder

Purpose: To determine the effect of delay to surgery on functional outcome in patients with operatively-treated acetabular fractures.

Method: Two hundred and thirty-two patients with acetabular fractures were identified from a pelvic trauma database. Functional outcome data was assessed using the validated Musculoskeletal Functional Assessment (MFA) and the Short Form 36 (SF-36) surveys in 162 patients. After 1997, functional outcome scores were collected prospectively at 6 months, 1 year and 2 years (or greater) post-operatively. Functional outcome scores, quality of reduction, and risk of complications were modeled as a function of days of delay to surgery via multivariate regression analysis adjusting for age, gender, fracture type, and associated injuries.

Results: At 6 months post-operatively, functional outcome scores were significantly worse with increasing delay to surgery. A delay of between 7 and 13 days or 14 or more days decreased the SF-36 physical component (PCS) z-scores by 0.75 (95% CI: −1.41 to −0.09) and 1.5 standard deviations (95% CI: −2.43 to −0.56) respectively. Delay of 14 or more days was associated with a worsening of the lower extremity (Move) subsection of the MFA by 18.6 points (95% CI: 3.3 to 33.8). Delay to surgery was associated with a significantly higher risk of poor reduction among those with available radiographic follow-up (n=67). Delay 14 days or more was associated with a 5 times (95% CI?.04 to 23.99) greater risk of a post operative step or gap over 2 mm. Delay to surgery was associated with an increase in thrombotic complications. In those patients who were diagnosed with a pulmonary embolism(PE) the mean delay was 11.3 days versus 7.3 days for the rest of the cohort (p=0.01). For patients with a deep vein thrombosis (DVT) average delay was 14.1 days versus 7.1 days (p=0.01).

Conclusion: Delay to surgery is associated with worsening functional outcome scores after as little as 7 days of delay. After 14 days, functional outcomes deteriorate further and radiographic outcomes are negatively influenced. Increased delay also increases risk of thrombotic events. These conclusions underscore the importance of timely treatment for displaced acetabular fractures.

Sprint Investigators Emil H. Schemitsch

Purpose: Accurate prediction of re-operation following tibial nailing may facilitate optimal patient care. We recently completed the SPRINT trial, a large, multi-centre trial of reamed versus non-reamed intramedullary nails in 1226 patients with tibial shaft fractures. Using the SPRINT data, we conducted an investigation of baseline and surgical patient characteristics to determine if they are associated with increased risk of re-operation within one year.

Method: Using multivariable logistic regression analysis, we investigated 15 characteristics for association with increased risk of re-operations. Because the primary SPRINT analysis found that reamed nailing reduced events in patients with closed but not open fractures, we considered both open and closed as well as treatment status in our model.

Results: We found an increased risk of re-operation in patients with a high energy mechanism of injury (odds ratio, OR=1.57, 95% CI 1.05 to 2.35), stainless steel versus titanium nail (OR=1.52, 95% CI 1.10 to 2.13), fracture gap (OR=2.40, 95% CI 1.47 to 3.94) and post-operative weightbearing (OR=1.63, 95% 1.003 to 2.64). Open fractures increased the risk of re-operation in patients who received a reamed nail (OR=3.26, 95% CI 2.01 to 5.28) but not in patients who received a non-reamed nail (OR=1.50, 95% CI 0.92 to 2.47). Patients with open fractures who had either wound management without any additional procedures, or delayed primary closure, had a decreased risk of re-operation when compared to patients who required subsequent reconstruction (respectively, OR=0.18, 95% CI 0.09 to 0.35; OR=0.29 95% CI 0.14 to 0.62).

Conclusion: To ensure optimal patient care surgeons should consider the characteristics identified in our analysis to reduce risk of re-operation.

Gillian Bayley Wade Gofton Allan Liew Steven Papp

Purpose: To compare the accuracy of post-operative plain radiographs versus computed tomography (CT) scans for the assessment of acetabular fracture reduction.

Method: A retrospective assessment of sixty-four fractures in sixty-two patients was performed independently by three orthopedic trauma surgeons. Pre-operative CT scans and three plain radiographs (one anteroposterior pelvis and two Judet views) were used to classify the fracture pattern and measure pre-operative articular step and gap. Post-operative reduction quality was assessed using three plain radiographs and an axial CT assessing for step, gap, intra-articular hardware or fragments and necessity to re-operate.

Results: Fracture patterns were as follows; posterior wall (n=10), posterior column (n=1), anterior wall (n=4), anterior column (n=1), transverse (n=12), posterior column posterior wall (n=4), transverse posterior wall (n=8), T-type (n=6), anterior column posterior hemi-transverse (n=5) and associated both column (n=11). Pre-operatively, the average step and gap on plain radiographs was 8.7 mm (±SD) and 15.3 mm (±SD). Post-operatively, the average step and gap was 0.6 mm (SD) and 0.9 mm (SD) based on 46 patients. The assessment was not possible in 18 patients due to overlying hardware. Using plain radiographs, one patient was found to have an inadequate reduction (> 2mm step and/or > 3mm gap). Post-operative measurement of step and gap by CT scan were 1.2 mm (SD) and 2.3 mm (SD) respectively. Using CT scans, eight patients were found to have either an inadequate reduction, intra-articular hardware or retained fragments. Computed tomography demonstrated 2 times more step and gap compared to plain radiographs.

Conclusion: Post-operative CT was found to be more sensitive than plain radiographs to assess the quality of acetabular fracture reduction. Plain radiographs detected only 1 out of 8 cases where further operative intervention may have been beneficial. Given the consequences of missing an unacceptable reduction, intra-articular hardware, or retained intra-articular fragments, it is recommended that all fractures should be assessed postoperatively with CT unless the patient is not a candidate for further surgery for reasons independent of reduction quality. The benefits of post-operative CT imaging in acetabular fractures likely outweigh the cost and radiation exposure associated with its use.

Geoffrey Wilkin Steven Papp Wade Gofton Allan Liew

Purpose: The purpose of this study was to review our results in patients with pilon fractures treated with ORIF in which surgical planning involved multiple skin incisions, ensuring that the distance incisions overlapped was less than the distance between them. We hypothesized that soft-tissue complications would be minimal despite incisions placed < 7-cm apart.

Method: A retrospective chart review identified 37 pilon fractures in 32 patients treated by three orthopedic traumatologists at The Ottawa Hospital between August 2000 and February 2007. Follow-up included measurements of incision placement and functional outcome measures.

Results: There were nine OTA type B and 28 OTA type C fractures; 28 were closed and nine were open. The mean age was 46.5 ±14.5 years, and average follow-up was 3.2 ±1.7 years. Of the patients reviewed, the average number of incisions was 3.7 ±1.1. The average overlap between incisions was 4.6-cm ±1.9 and the average skin bridge between incisions was 5.9-cm ±1.9, with 80% of the skin bridges < 7-cm. Average ROM was 4.3° ±7.1 dorsiflexion and 39.1° ±11.6 plantarflexion. The mean AMA lower extremity impairment score was 18.9% ±12.4, and mean SIP ambulation score was 9.6 ±8.8. Complications included two superficial infections, one deep infection, and three non-unions. There were no cases of wound dehiscence or necrosis, or cases requiring revision soft-tissue coverage. These outcomes were comparable to recent reports with similar injuries.

Conclusion: With careful planning and good soft-tissue management, incisions can be placed to maximize articular exposure based on fracture lines. It does not appear that the dogma of keeping incisions > 7-cm apart must be followed in most cases. Prudent surgical timing and meticulous soft-tissue handling can allow for multiple incisions to be placed as necessary for fracture reduction and optimal fixation while maintaining a low rate of complications.

Jeffrey M. Potter Lise Leveille Pierre Guy

Purpose: Lower extremity articular fracture treatment requires acccurate diagnosis and anatomic reduction and fixation. As articular injuries, posterior malleolus (PM) fractures are still poorly defined: for example the incidence of associated PM marginal impaction and of free articular fragments is unknown. The purposes of this study were:

to define the articular injuries of PM fractures into clincially relevant groups, as complex articular injuries could require specific surgical steps;

to identify clinical and radiographic parameters which would alert the surgeon to the presence of complex injuries.

Method: Our prospectively-collected orthopaedic trauma database (OTDB) query identified 796 ankle fractures treated operatively between 2003–2007. Of these 147 cases involved the posterior malleolus. Four were misclassified leaving 143 cases. We obtained demographic and injury data from the OTDB, and validated the OTDB coded mechanisms of injury by an individual chart review. We reviewed all radiographs to describe the PM injuries (fracture patterns and dimensions) and to identify the associated injuries.

Results: Of the 143 cases: Mean age was 50 years (sd=19), 68.5% were female, 51% were right sided injuries, and the median ISS=4 (in fact, 97.5% had ISS=4, most therefore being isolated trauma). The mean post malleolus AP size=11mm (sd=5). We identified recurrent patterns and classified the PM fracture as SIMPLE or COMPLEX (to include marginal impaction or free comminuted fragment, which should be anatomically reduced), 42% of cases (60/143) were COMPLEX (18 were impaction, 42 were free fragment). To help clinicians identify which cases could be COMPLEX we correlated (Chi-sq) the presence of a COMPLEX PM fracture to common clinical and radiographic variables. COMPLEX PM were statistically significantly associated with (p values)

an axial loading injury mechanism (.000),

a radiographically captured dislocation (.006),

posteromedial comminution [as defined Tor-netta] (.005)

the size of the fragment (.000).

For example, axial loading would result in a complex fracture in > 85% of cases. In contrast, there was a statistically significant association between a Weber C fracture and older age and the presence of a SIMPLE PM fracture. These factors being potentially “protective” from joint comminution.

Conclusion: We have defined and quantified the PM articular lesions which require anatomic reduction and fixation, beyond what has been published. We have defined clinical and radiographic criteria which, because higly associated with COMPLEX lesions, could

prompt surgeons to order further imaging (CT) to better delineate the lesion, and

draw his/her attention to potentially malaligned fragments at the time surgery.

Piya Kiatisevi Torsten Nielsen Malcolm Hayes Peter L. Munk Amy E. LaFrance Paul Clarkson Bassam A. Masri

Purpose: Core needle biopsy is increasingly accepted for the diagnosis of bone and soft-tissue tumours. Advantages over open biopsy include reduced morbidity, time and cost; however diagnostic accuracy remains a concern. Our objective was to assess and compare the diagnostic accuracy of core needle, open, and fine needle biopsies.

Method: We reviewed 286 cases collected in a prospective database between 2004 and 2007. Of these, 229 had core needle, 32 open, and 25 fine needle biopsies. 230 had soft-tissue lesions, 56 had bone lesions. The results of these biopsies were compared to the final resection diagnosis for accuracy and, where inaccurate, any effects on management.

Results: Ninety-two percent of the core needle, 100% of the open and 72% of the fine needle biopsies had adequate tissue to make a diagnosis. Of the adequate specimens, the accuracy of core/open/fine needle biopsy was 96%, 97% and 94% for determining malignant versus benign; of the correctly identified malignant lesions 97%, 100% and 80% were accurate for histological grade; and 79%, 84%, 59% for histological subtype.

Conclusion: Core needle biopsy yields diagnostic results comparable to open biopsy for determining malignancy and grade in bone and soft-tissue tumours. Fine needle biopsy has a high inadequate sampling rate and should not be used for diagnosing bone and soft-tissue tumours. Given the reduced cost and morbidity associated with core needle biopsies we believe they should be used routinely for diagnosis where possible, and open biopsy reserved for situations where an inadequate specimen is obtained or core biopsy is not feasible.

Nanjundappa S. Harshavardhana Brian J.C. Freeman Alan C. Perkins Ujjwal K. Debnath

Purpose: Intra-op localisation of small nidus in Osteiod osteoma and Osteoblastomas is often difficult resulting in failed excision with persistent pain. We report two year follow-up results of the efficacy and reliability of using an intra-operative gamma probe in conjunction with fluoros-copy to aid resection in primary and revision surgeries.

Method: Eight patients (6M; 2F) with a diagnosis of osteoid osteoma (7) and osteoblastoma (1) were seen at our centre. The mean age at presentation was 20.9 years (9–31y). The tumour was localised to cervical (2), thoracic(4) and lumbar (2) posterior elements. All had back or neck pain of varying duration with a mean of 20 months (6–48mo). Three patients had failed treatments including CT-guided radiofrequency ablation in one and surgical excision under fluoroscopy in two. No case had previously utilised an intra-op gamma probe for localisation. All patients had work-up with plain X-rays, CT, MRI and 99 m Technetium bone scan to identify and localise the lesion. A pre-requisite for use of intra-op gamma probe was a positive pre-op bone scan. On the day of surgery, 600 MBq Tech HMDP (hydroxy-methylene-di-phosphate) was administered IV 3 hours prior to surgery. Fluoroscopy was used to confirm anatomical level, permanent mark made on skin and area exposed surgically. A 5 mm cadmium telluride (Cd Te) probe (which converts gamma radiation into electrical signal) and rate meter were used to scan the area containing lesion and counts per second(cps) recorded. The tumour nidus was then excised and cps from tumour bed and excised specimen recorded.

Results: The mean follow-up was 5.85 years (2–12.3y). The mean cps for osteoid osteoma pre-excision was 203.8 (60–515), which fell to 72.5 (10–220) post-excision. The cps reduced from 373 to 40.5 post-operatively for Osteoblastoma. Complete excision was recorded every time and all patients reported characteristic disappearance of pre-operative pain. All had discontinued analgesic medication and returned to normal activity by three months. All patients were followed-up regularly when they filled NDI, ODI and SF-36.

Conclusion: Gamma probe guided surgical excision facilitates accurate localisation of lesion, is less invasive and most importantly confirmation of complete excision of the tumour nidus consistently every time.

Frank M. Klenke Doris E. Wenger Carrie Y. Inwards Franklin H. Sim

Purpose: Giant cell tumor (GCT) of bone is a rare, usually benign, primary skeletal lesion. The disease’s clinical course may be complicated by local recurrence subsequent to surgical treatment or the development of benign pulmonary metastases. Intra-lesional curettage is the standard treatment of primary GCT of bone. However, the value of intralesional procedures in recurrent GCT has not been well established.

Method: Forty-six patients with recurrent GCT of long bones treated between 1983 and 2005 were followed retrospectively. Minimum follow-up was three years; mean follow-up was 11.1 (±4.8) years.

Results: Wide resections were performed in 18 patients. Intralesional, joint preserving procedures were performed in 28 patients. Subsequent recurrence occurred in nine patients (20%). Wide resection was performed if joint salvage was not achievable due to expansion of the tumor. Reconstructions following wide resection included arthroplasty (n=4), osteoarticular allograft (n=3), APC (n=1) and fibular autograft reconstruction of the wrist (n=3). Amputations were performed in two patients. Patients undergoing wide resections for local recurrence had a significantly smaller risk of subsequent recurrence as compared to patients treated with intra-lesional surgery (6% versus 32%, hazard ratio: 0.28, p< 0.05). In patients treated with intralesional surgery, application of polymethylmethacrylate (PMMA) in addition to local phenol treatment significantly reduced the risk of subsequent recurrence (PMMA + phenol: 7% vs. Phenol: 25%, hazard ratio: 0.23, p< 0.05). Soft tissue expansion was not associated with an increased risk of subsequent recurrence. At follow-up, all patients with subsequent recurrence were without local disease after additional intralesional surgery (n=3) or wide resection (n=5). Metachronous benign pulmonary metastases evolved in five cases. There was no correlation between the development of pulmonary metastases and the type of treatment of recurrent disease found.

Conclusion: In recurrent disease of GCT of long bones and the possibility to salvage the adjacent joint intra-lesional surgery is the treatment of choice independent of whether soft tissue expansion is present. Intra-lesional surgery does not increase the risk of development benign pulmonary metastases. In cases with extensive tumor formation and without the possibility to preserve the adjacent joint wide resection has a high chance for long-term recurrence free disease.

Kevin B. Jones Soha Riad Anthony Griffin Benjamin Deheshi Robert S. Bell Peter Ferguson Jay S. Wunder

Purpose: The functional consequences of femoral nerve resection during soft tissue sarcoma management are not well described. Sciatic nerve resection with a sarcoma, once considered an indication for amputation, is now commonly performed during limb salvage. We compared the functional outcomes of femoral and sciatic nerve resections in patients undergoing wide resection of soft-tissue sarcomas.

Method: The prospectively collected database from a tertiary referral center for sarcomas was retrospectively reviewed to identify patients with resection of the femoral or sciatic nerve performed during wide excision of a soft tissue sarcoma. Patient demographics, treatment, complications and functional outcomes were collected.

Results: Ten patients with femoral nerve resections were identified, all women, aged 47 to 78, with large soft tissue sarcomas of varied subtypes. All patients received adjuvant radiotherapy, most pre-operatively. Six patients developed fractures with long-term follow-up, only two of which were in the prior radiation field. Musculoskeletal Tumor Society (MSTS) 1987 scores demonstrated one excellent, 4 good, and 5 fair results. MSTS 1993 scores averaged 71.4 ± 17.2 percent and Toronto Extremity Salvage Scores (TESS) averaged 61.7 ± 21.8. There were no significant differences between the functional scores for patients with femoral or sciatic nerve resections (P=1.0).

Conclusion: Femoral nerve resection appears more morbid than anticipated. The falls to which patients were prone, even years after surgery, subject them to ongoing long-term risks for fractures and other injuries. Nerve-specific functional outcomes should be considered when counseling patients prior possible resection of the femoral nerve for involvement by a soft tissue sarcoma.

Sarantis Abatzoglou Abdurahman Adoubali Cindy Wong Marc Isler Robert É. Turcotte

Purpose: Management of local recurrence (LR) remains unclear. Optimal management of primary tumour by specialised teams minimises this risk. However, previous treatments may impact on the available options when LR is encountered. We thus studied the outcome of this population with recurrent STS.

Method: Retrospective review was carried based on our prospective sarcoma databases. DFSP and ALT were excluded. Among 618 primarily managed STS we found 35 cases of local recurrences (5.7%). Median f-up after LR was 14 mos (0–98).

Results: Twenty were female. Mean age was 54 (Range 15 – 92). 22 involved lower limb, 11 upper limb and 2 the trunk. Mean delay from original surgery was 23 mos (3–75) and the mean size of LR was 4.7 cm (0.4–28.0 cm). Primary tumours were superficial in 4 and deep in 31 while recurrences were found superficial in 8 and deep in 26. Most frequent histology was MFH 8, Leiomyosarcoma 6, Liposarcoma, synovial sarcoma and MPNST had 4 each. 84% were high grade. Only 23 showed no meta-static disease at time LR was diagnosed. All 5 pts without initial RT got RT for their LR. 7 pts with therapeutic level of RT to the primary tumour got full course of RT as well for their LR. 11 did not undergo surgery. 6/18 who had initial RT underwent amputation as opposed to 0/6 who did not. Trend to amputate was for younger age, deep and large tumour and previous RT. Ultimatly, 21(60%) locally recurrent tumours showed metastatic disease; 6 prior diagnosis of LR, 6 concomitantly and 9 after with an average delay of 17 months (1–24). 6 pts developed additional local recurrences.

Conclusion: Although infrequent local recurrence correlates with impaired outcome. Albeit challenging, limb salvage and additional radiotherapy remain possible despite optimal multi modality management of the initial tumour.

Kevin B. Jones Soha Riad Anthony Griffin Benjamin Deheshi Robert S. Bell Peter Ferguson Jay S. Wunder

Purpose: Few functional outcomes of total femoral endoprosthetic replacement (TFEPR) using contemporary modular systems are available. We compared functional results between TFEPR patients receiving fixed- and rotating-hinge knee componentry following oncologic resections.

Method: Eighteen TFEPR patients were identified from a prospectively gathered sarcoma database. Six were secondary procedures and 12 primary. Four patients had metastatic carcinoma, 8 osteosarcoma, 4 non-osteogenic spindle cell sarcomas of bone, 1 Ewing’s sarcoma, and 1 femur-invading soft-tissue sarcoma. All reconstructions used modular implants from a single company. Proximally, all were bipolar hip hemiarthoplasties, 12 including abductor reattachment. Distally, 8 had fixed- and 10 had rotating-hinge knee componentry. Toronto Extremity Salvage Score (TESS), and both Musculoskeletal Tumor Society Scores (MSTS) were compared between fixed- and rotating-hinge groups using the Mann-Whitney test.

Results: Complications included 1 hip dislocation, 1 femoral malrotation, and wound problems requiring 3 debridements and 1 amputation. One metastatic carcinoma patient developed local relapse. Follow-up averaged 4 years (range 1 month to 14 years). At latest follow-up, 10 patients had died of disease. Eight remained alive, 6 disease-free, 2 with distant disease. Among patients surviving 6 months, 6 used no assistive devices, 5 used a single cane, and 4 were wheelchair bound, each at least partly due to distant disease progression. TESS averaged 74.5±17.4, MSTS1987 25.2±4.4; and MSTS1993 58.6±22.9 among the 12 patients for whom functional results were available from latest follow-up. No statistically significant differences or even trends were detected between fixed-hinge and rotating-hinge patients (lowest p = 0.755), but both instability problems were in the rotating-hinge group.

Conclusion: While both rotating- and fixed-hinge TFEPR reconstructions may function well, consideration should be given to fixed-hinge knee reconstruction when massive myectomies or poorer conditioning make hip and knee stability a primary concern in the short-term.

Paul Clarkson Kelly L. Sandford Amy E. LaFrance Anthony Griffin Jay S. Wunder Bassam A. Masri Thomas J. Goetz

Purpose: Giant cell tumour (GCT) of the distal radius is associated with high local recurrence rates unless the tumour is aggressively resected, which often leaves a significant skeletal defect. The purpose of this study is to compare the functional outcomes of two commonly used reconstructive techniques, vascularised free fibular transfer (VFF) and non-vascularised structural iliac crest transfer (NIC).

Method: Patients treated for giant cell tumour of the distal radius in either Vancouver or at Mount Sinai Hospital, Toronto were identified in the prospectively collected databases maintained in each centre. Twenty-seven patients were identified, 14 of whom underwent VFF transfer as their primary procedure. The two groups were comparable for age, sex and tumour grade. Functional outcomes were assessed with TESS, MSTS, DASH and the Ankle Osteoarthritis Scale.

Results: Fourteen patients were included in the VFF group, 13 of which were performed as the primary index procedure, one followed prior cementation. Thirteen patients underwent NIC, one followed prior cementation. Two local recurrences occurred in the VFF group and one in NIC group, all treated with local excision. In the VFF group three patients underwent further surgery for cosmesis, hardware removal and tendon release respectively. One is scheduled for future surgery for tendon release. In the NIC group two patients suffered infections requiring debridement, one of which ultimately went on to require free fibular transfer. This patient’s results were included in the NIC group as this was the index procedure. Functional scores showed no differences between the two groups on any of the parameters studied for the upper limb (Mann-Whitney test). The Ankle osteoarthritis scale had a median score of 9% for the six patients on which it was available.

Conclusion: Both VFF and NIC are effective surgical techniques that result in a well-functioning wrist arthrodesis. VFF may be more useful where there is a significant skin defect from previous interventions. We were unable to demonstrate any difference in functional scores between VFF and NIC.

David Sheps Fiona Styles-Tripp Kyle Kemp Scott Wiens Lauren Beaupré Robert A. Balyk

Purpose: Arthroscopic stabilization for post-traumatic anterior glenohumeral instability is designed to minimize soft tissue dissection while achieving similar or improved outcomes relative to open techniques. This study’s purpose was to determine the rate of post-operative recurrent instability and evaluate health related quality of life (HRQL) and shoulder range of motion (ROM) following arthroscopic Bankart repair using a bioabsorbable knotless implant.

Method: Forty-three patients were prospectively evaluated following arthroscopic anterior stabilization to assess for recurrent instability, HRQL, and shoulder ROM. Assessments were performed pre-operatively and 3, 6 and 12–24 months postoperatively. The HRQL measures included the Western Ontario Shoulder Instability Index (WOSI), the American Shoulder and Elbow Surgeons Score (ASES), and the Constant Score. Repeated measures ANOVA was utilized to evaluate ROM and HRQL.

Results: The mean WOSI score improved from 45.67±17.99 pre-operatively to 83.16±18.58 at final follow-up. The mean ASES scores improved from 80.1±13.06 pre-operatively to 92.25±15.08, while the Constant score improved from 77.52±16.11 pre-operatively to 85.18±26.76. At final follow-up, 4 of 43 patients (9.3%) had experienced recurrent instability. For these 4 subjects, the WOSI score was significantly lower at final follow-up than those who did not experience recurrent instability (61.73±5.76 versus 84.38±16.94). The ASES and Constant scores at final follow-up were not significantly different between these two groups.

Conclusion: Arthroscopic anterior stabilization using a bioabsorable tack led to a recurrent instability rate similar to previous reports, and resulted in improved HRQL and shoulder ROM. The WOSI score was better able to detect problems in HRQL related to instability than either the ASES or Constant score.

Jaskarndip Chahal Tom McCarthy Jeff Leiter Daniel B. Whelan

Purpose: To determine whether generalized ligamentous laxity is a predisposing factor for primary traumatic anterior shoulder dislocation in young, active patients.

Method: Prospective case series with age and sex matched controls. The Hospital Del Mar Criteria was utilized to measure generalized ligamentous laxity. Fifty-seven (n=57) consecutive individuals (age< 30) sustaining a primary traumatic anterior shoulder dislocation between 2003 and 2006 were examined for hyperlaxity. The control group was comprised of seventy-two (n=72) undergraduate university students without a prior history of shoulder dislocation or anterior cruciate ligament injury.

Results: After adjusting for age and sex, the prevalence of hyperlaxity in the study group was 32.8% compared with 10.4% in the control group (p< 0.01). The prevalence of increased contralateral shoulder external rotation (> 85o) was 40.3% in the study group compared with 20.8% in the control group (p< 0.03). Among males, the prevalence of hyperlaxity was 28.3% in the study group and 5.3% in the controls (p< 0.01).

Conclusion: Although several studies have looked at the variables affecting shoulder instability, generalized ligamentous laxity (as measured by validated criteria) has not previously been identified as a predisposing factor for primary traumatic shoulder dislocation. This study demonstrates that generalized joint laxity and increased external rotation in the contralateral shoulder were found to be more common in patients who had sustained a primary shoulder dislocation. These observations may suggest a role for shoulder-specific proprioceptive and strength training protocols in hyperlax individuals participating in high-risk sports. Furthermore, the implications of hyperlaxity on the surgical management of traumatic primary shoulder instability are uncertain.

Arvindera Ghag Kyle Winter Erin Brown Amy E. LaFrance Paul Clarkson Bassam A. Masri

Purpose: Resection of pelvic sarcoma with limb preservation (internal hemipelvectomy) is a major undertaking. Resection requires large areas of soft-tissue to be removed. Because of wound complications, we manage these defects with immediate tissue transfer (ITT) at the time of resection when a large defect is anticipated. This study compares the outcomes of ITT with primary wound closure (PWC).

Method: Twenty patients undergoing 22 separate procedures (1995–2007) were identified in our prospectively maintained database. Demographics, tumour type, operative data and complications, and functional scores (MSTS-1993, TESS) were collected.

Results: Twelve defects were managed with ITT, nine with pedicled myocutaneous vertical rectus abdominis (VRAM) flaps (one received double VRAM flaps due to the large defect), two with tensor fascia lata (TFL) rotation flaps (one augmented by local V-Y advancement, the other with gluteus maximus rotation flap) and one received latissimus dorsi free tissue transfer. Four wound complications necessitated operative intervention in this group: two debrided VRAM flaps went on to heal and the two TFL flaps required revision: one to VRAM flap and the other to a latissimus dorsi free flap which ultimately suffered chronic infection and hindquarter amputation was performed. Ten defects were managed with PWC, and 5 wound complications occurred, all five suffered infection, one developed hematoma and one dehisced. One wound resolved with debridement, two healed after revision to pedicled gracilis and gluteus maximus myocutaneous flaps. Two patients were converted to hindquarter amputation due to chronic infection. Functional scores were collected on 8 of 12 living patients, at time of writing. The mean TESS scores were 83 and 73 in the ITT and PWC groups. Five patients in the ITT and 3 in the PWC group were deceased.

Conclusion: Soft-tissue closure following pelvic sarcoma resection remains a difficult challenge, and our experience reflects that. There were fewer wound complications (33% v 50%) and slightly better function with ITT than PWC, but this was not statistically significant due to the small size of our study. Although small, this study suggests ITT should be considered whenever a large soft tissue defect is anticipated.

Randy Mascarenhas Champ L. Baker Alex J. Kline Anikar Chhabra Mathew Pombo James P. Bradley

Purpose: There are few reports in the literature detailing the arthroscopic treatment of multidirectional instability of the shoulder. The purpose of this study was to evaluate the results of arthroscopic methods in the treatment of athletes with symptomatic multidirectional instability of the shoulder.

Method: Forty patients (43 shoulders) with multidi-rectional instability of the shoulder were treated via arthrscopic means and were evaluated at a mean of 33.5 months post-operatively. The mean patient age was 19.1 years (range 14 to 39). There were 24 male patients and 16 female patients. Patients were evaluated with the ASES and WOSI scoring systems. Stability, strength, and range of motion were evaluated with patient-reported scales.

Results: The mean ASES score postoperatively was 91.4 out of 100. The mean WOSI post-operative percentage score was 91.1 out of 100. Ninety-one percent of patients had full or satisfactory range of motion, 98% had normal or slightly decreased strength, and 86% of patients were able to return to their sport with little or no limitation.

Conclusion: Arthroscopic methods can provide an effective treatment for symptomatic multidirectional instability in an athletic population.

Inder Gill Ajay Malviya Scott Muller Mike Reed

Purpose: To assess the infection rate following Lower Limb Arthroplasty using single dose gentamicin antibiotic prophylaxis compared to a traditional three doses of cephalosporin.

Method: All patients undergoing Total Hip and Knee replacements over six months (October 2007 to March 2008) at three participating hospitals were prospectively followed to assess perioperative infection rates using Surgical Site Surveillance(SSI) criteria. All patients received single dose antibiotic prophylaxis using intravenous Gentamicin 4.5mg/kg. This was compared with previous data collected over a 6 month period (Jan to Mar 2007 and Oct to Dec 2005) from the same hospitals using 3 doses of Cefuroxime 750mg. Return to theatre data was collected independently after introduction of gentamicin to compare with previous data. The change in creatinine level postoperatively was also measured in a selected group of patients.

Results: Four hundred and eight patients underwent Total Hip Replacements (THR) and 458 patients Total Knee Replacements (TKR) during the study period. This was compared with 414 and 421 patients who underwent THRs and TKRs respectively during a previous six month period. SSI was detected in 9 THRs(2.2%) and 2 TKRs(0.44%) in the study group as compared to 13 THRs(3.1%) and 12 TKRs(2.9%) in the control group. The infection rates in THRs were not significantly different between the 2 groups(p value−0.52) but were significantly reduced in the study group for TKRs(p value−0.005). The rate of Clostridium difficile infection was reduced within the hospital with the use of gentamicin, although other measures to reduce its incidence were also introduced. The return to theatre was 1.64%(23/1402) after introduction of Gentamicin as compared with 1.05%(21/2005) [p value−0.092] before this. This was a cause for concern although not significant. The day1 postoperative creatinine level increased by more than 30 units in 6% of patients on Gentamicin.

Conclusion: This study shows that the use of single dose prophylaxis using Gentamicin is effective for Lower Limb Arthroplasty. However, be wary of increased rate of return to theatre and the rise in creatinine level following use of gentamicin. Further period of evaluation and study is needed before it is recommended for routine use in present or modified form.

Ryan Bicknell Chris Chuinard Scott Penington Frédéric Balg Pascal Boileau

Purpose: Shoulder pain in the young athlete is often a diagnostic challenge. It is our experience that this pain can be related to a so-called “unstable painful shoulder” (UPS), defined as instability presenting in a purely painful form, without any history of instability but with anatomical (soft tissue or bony) ‘roll-over’ lesions. The objectives are to describe the epidemiology and diagnostic criteria and to report the results of surgical treatment.

Method: A prospective review was performed of 20 patients (mean age 22 ± 8 years). Inclusion criteria: a painful shoulder and “roll-over lesions” on imaging or at surgery. Exclusion criteria: a dislocation/subluxation; associated pathology; previous shoulder surgery.

Results: Most patients were male (60%), athletes (85%) and involved the dominant arm (80%). All patients denied a feeling of instability and only complained of deep, anterior pain. Most had a history of trauma (80%). All patients had rehabilitation without success and 30% had subacromial injections. All had to stop sports. Most (85%) had anterior or inferior hyperlaxity. All had pain with an anterior apprehension test and relieved by relocation test. ‘Roll-over’ lesions included: labrum detachment (90%), capsular distension (75%), HAGL lesion (10%), glenoid fracture (20%) or Hill-Sachs (40%). Time from symptoms to surgery was 25 ± 23 months. All patients had arthroscopic treatment. Mean follow-up was 38 ± 14 months. Eighteen patients (90%) were very satisfied/satisfied. None had pain at rest, but one (5%) had pain with apprehension test. There was no change in elevation, external or internal rotation (p> 0.05). There were no cases of instability. Rowe and Duplay scores improved (p< 0.05).

Conclusion: Instability of the shoulder can present in a purely painful form, without any history of dislocations or subluxations. Diagnosis can be difficult, and should be suspected in young patients and athletes. Most patients have deep anterior pain and pain with apprehension test. ‘Roll-over’ lesions are necessary to confirm the diagnosis. Arthroscopic repair is effective.

Scott Kaar Stephen Fening Morgan Jones Rob Colbrunn Anthony Miniaci

Purpose: We hypothesized that glenohumeral joint stability will decrease with increasingly larger humeral head defects.

Method: Humeral head defects were created in 9 cadaveric shoulders to simulate Hill Sachs defects. Defects represented 1/8, 3/8, 5/8, and 7/8 of the radius of the humeral head. Secondary factors included abduction angles of 45 degrees and 90 degrees, and rotations of 40 degrees internal, neutral, and 40 degrees external. Specimens were tested at each defect size sequentially from smallest to largest and at each of 6 conditions for all abduction and rotation combinations. Using a 6 degree-of-freedom robot, the humeral head was translated at 0.5 mm per second until dislocation in the anteroinferior direction at 45 degrees to the horizontal glenoid axis.

Results: ANOVA demonstrated significant factors of rotation (p< 0.001) and defect size (p< 0.001). In 40 degrees external rotation, there was significant reduction of distance to dislocation compared with neutral and 40 degrees internal rotation (p< 0.001). The 5/8 and 7/8 radius osteotomies demonstrated decreased distance to dislocation compared to the intact state (p< 0.05 and p< 0.001 respectively). There was no difference found between abduction angles. Post hoc analysis determined significant differences for each arm position. There was decreased distance to dislocation at the 5/8 radius osteotomy at 40 degrees external rotation with 90 degrees of abduction (p< 0.05). For the 7/8 radius osteotomy at 90 degrees abduction, there was decrease distance to dislocation for neutral and 40 degrees external rotation (p< 0.001). For the same osteotomy at 45 degrees abduction, there was decreased distance to dislocation at 40 degrees external rotation (p< 0.001). With the humerus internally rotated, there was never a significant change in the distance to dislocation.

Conclusion: Glenohumeral stability decreases at a 5/8 radius defect and was most pronounced in 40 degrees external rotation and at 90 degrees abduction. At a 7/8 radius humeral defect, there was further decrease in stability at both neutral and external rotation. Internal rotation always maintained baseline glenohumeral stability.

R. Cole Beavis F. Alan Barber Morley A. Herbert

Purpose: New high-strength sutures demonstrate high failure loads, but may be more likely to slip compared with polyester sutures. The purpose of this study was to determine the knot security and ultimate failure load of 8 common sutures tied with 6 arthroscopic knots. The hypothesis was that knots tied using high-strength sutures would not slip and demonstrate greater tensile strengths than polyester suture.

Method: Eight different sutures (Ethibond, FiberWire, ForceFiber, Hi-Fi, MagnumWire, Maxbraid, Ortho-cord and Ultrabraid) were tied with 6 arthroscopic knots (Duncan, Revo, San Diego, SMC, Tennessee and Weston.) Knots were backed up with 4 reversed half-hitches on alternating posts. Each suture-knot combination was tied 10 times for a total of 480 knots tested. Cyclic testing was performed followed by loading to failure. Mode of failure, ultimate failure load and force during slippage was recorded.

Results: FiberWire demonstrated the highest failure load (259.70N+/−85.81) and Ethibond the lowest (143.92N+/−16.56) (p< 0.05). Knots tied with Ethibond slipped 22.4% of the time compared with 31.7%–40.0% for high-strength sutures. Frequent slippage occurred with Duncan loops (97.5%) and Weston knots (86.3%) while the SMC (1.3%) and Revo knots (3.6%) rarely slipped (p< 0.05). Mean failure loads were highest for the Revo (280.99N +/− 57.01) and SMC knots (274.89N +/−57.90) compared with all others (p< 0.05).

Conclusion: Our results demonstrate that knots tied with Ethibond were least likely to slip and yielded a more consistent (narrow standard deviation) but overall lower ultimate tensile strength than all of the high strength sutures. Early slippage of some knots tied with high-strength suture was responsible for greater variability with some failing at sub-maximal loads. The Duncan loop and Weston knots were the most likely to slip.

Alan M. Hirahara Kyle Yamashiro Russell Dunning

Purpose: To evaluate failure rates of SLAP repairs with and without a fibrin-PRP clot.

Method: 141 patients received a fibrin-PRP clot, placed arthroscopically between the labrum and bone prior to tying our sutures in repairing the SLAP lesion. Thirty-nine patients were repaired without use of a fibrin-PRP clot. Arthroscopic fixation was performed using a bio-absorbable suture anchor (Bio-SutureTak, Arthrex). The fibrin-PRP clot was made from autologous blood, using the Plasmax Plus system (Biomet). Patients were evaluated clinically with ASES scores, range of motion, time to discharge, and return to work. Repeat MRA or surgery was performed for people having persistent pain or complaints at four to six months post-operatively to evaluate healing.

Results: Four out of thirty-nine (10.3%) control patients failed to heal and required revision surgery. One out of 139 (0.7%) study patients failed to heal (p = 0.008). Pain scores decreased from pre-op to 1 to 3 to 6 months in both groups but significantly greater in the study group (7.1, 5.2, 3.0, 1.6) compared with the control group (7.1, 6.0, 4.8, 3.1) (p=NS, NS, < 0.001, < 0.05). ASES society scores increased steadily from pre-op to 1 month to 3 months to 6 months in both groups. The control group increased from 35.9 to 36.9 to 56.3 to 72.7. The study group increased from 43.1 to 45.2 to 71.0 to 81.9 and were significantly different (p = NS, < 0.05, < 0.001, 0.06). The average days to discharge in the study group was significantly improved at 119.1 days from 213.5 in the control group (p < 0.001). Time to return to work decreased from control to the study group 121.7 days to 57.1 days (p < 0.01). ROM increased in both groups non-significantly from pre-op to 3 months follow up in the study group.

Conclusion: The results of this study show that the fibrin-PRP clot enhances the healing of the labrum to the glenoid. We have significantly fewer failures, less pain, quicker time to discharge, and faster functional recovery. By suturing a fibrin-PRP clot between the labrum and glenoid, recovery and healing of the tear occurs quicker and more reliably.

Nicholas G.H. Mohtadi Jocelyn N. Fredine Heather N. Hannaford Denise S. Chan Treny M. Sasyniuk

Purpose: Shoulder instability is a common problem affecting patients in their most active years resulting in an impact on their quality of life. The WOSI is a validated, disease-specific (shoulder instability) evaluative quality of life measure. It has not been tested for its ability to discriminate between those who require surgical care and those who do not. The purpose of this study is to determine if the WOSI can discriminate between surgical and non-surgical patients and between patients with different types of shoulder instability.

Method: Sixty patients with a confirmed diagnosis of shoulder instability were included as cases. Twenty had documented multidirectional instability requiring surgery: Group 1 Surgical MDI – 20 patients had documented recurrent traumatic anterior dislocations requiring surgery: Group 2 Surgical Anterior – 20 patients were first time anterior dislocators who were followed for a minimum one year who had no further recurrences and did not require surgery: Group 3 Non-Surgical First Time Anterior – The cases were compared to 60 age and gender matched control patients with no history of shoulder problems: Group 4 Control – WOSI scores were analyzed using a one-way ANOVA.

Results: The WOSI scores were as follows: Group 1 Surgical MDI- mean 30.5 (95% CI 23.1–37.8); Group 2 Surgical Anterior- mean 39.8 (95% CI 33.1–46.5); Group 3 Non-Surgical First time Anterior- mean 76.2 (95% CI 66.4–86.0) and Group 4 Control- mean 96.6 (95% CI 95.8–97.4). Based on the 95% Confidence Intervals, there were statistically significant differences between the two surgical groups (Group 1 Surgical MDI and Group 2 Surgical Anterior) compared to the non-surgical patients (Group 3 Non Surgical First Time Anterior) and the controls (P=0.000). There is a trend to discriminate between the two surgical groups (P=0.079).

Conclusion: The WOSI Index clearly discriminates between surgical and non-surgical patients with shoulder instability, and the control population with normal shoulders. There is a trend to discriminate between MDI and recurrent anterior traumatic dislocators.

Marlis Sabo Katherine Fay Louis M. Ferreira Colin P. McDonald James A. Johnson Graham J.W. King

Purpose: Coronal shear fractures of the humerus include the Kocher-Lorenz fracture, an osteochondral fracture of the capitellar articular surface, the Hahn-Steinthal fracture, a substantial shear fragment, extension into the trochlea, and complete involvement of the capitellum and trochlea. If the fracture proves irreparable, it is not known what the impact of fragment excision would have on the biomechanics of the elbow. The purpose of this study was to examine the effect of the sequential loss of the capitellum and trochlea on the kinematics and stability of the elbow.

Method: Eight fresh-frozen cadaveric arms were mounted in an upper extremity joint testing system, with cables attaching the tendons of the major muscles to motors and pneumatic actuators. Electromagnetic receivers attached to the radius and ulna enabled quantification of the kinematics of both bones with respect to the humerus. The distal humeral articular surface was sequentially excised to replicate clinically relevant coronal shear fractures while leaving the collateral ligaments intact. Active flexion in both the vertical and valgus-loaded positions, and passive rotation in the vertical position was conducted for each excision.

Results: Excision of the capitellum had no effect on ulnohumeral stability or kinematics in both the vertical or valgus positions (p=1.0). Excision of the entire capitellum and trochlea led to significant valgus instability with the arm in the valgus position (p=0.01), while excision of the lateral trochlea led to increased valgus instability with pronated flexion in the valgus position (p=0.049). Progressive loss of the articular surface led to posterior, inferior, and medial displacement of the radial head with respect to the capitellum and increased external rotation of the ulna with respect to the humerus in the vertical position (p< 0.05).

Conclusion: Excision of the capitellum did not result in valgus or rotational instability, while excision of the trochlea resulted in multiplanar instability. The radial head displaced medially because it is constrained to the ulna by the annular ligament, and the ulna pivoted into valgus and external rotation on the residual trochlea and medial collateral ligament. In patients with coronal shear fractures, the trochlea must be reconstructed to prevent instability and the potential for secondary degenerative change.

Holman Chan Martin Bouliane Lauren Beaupré

Purpose: Due to its proximity to the glenohumeral joint, the suprascapular nerve may be at risk of iatrogenic nerve injury during arthroscopic labral repair. Our primary objective is to evaluate the risk of suprascapular nerve injury during standard drilling techniques utilized in arthroscopic superior labral repairs. Secondarily, we evaluated the correlation between this risk and scapular size.

Method: Forty-two cadaveric shoulders were dissected to isolate their scapulae. A surgical drill and guide was used to create suture anchor holes in 3 locations in the superior rim of the glenoids as typically done in arthroscopic superior labral repairs. The orientation of these drill holes correspond to common shoulder arthroscopic portals. The suprascapular nerve was then dissected from the suprascapular notch to the spinoglenoid notch. The presence of drill perforations through the medial cortex of the glenoid vault was recorded along with the corresponding hole depth and distance to the suprascapular nerve.

Results: Medial glenoid vault perforations occurred in 8/21(38%) cadavers with a total of 18/126(14%) perforations. The suprascapular nerve was in line of the drill path in 5/18(28%) perforations. Female specimens and smaller scapulae had a statistically higher risk of having a perforation (p< 0.05).

Conclusion: The results of this anatomic study suggest that there is a substantial risk of medial glenoid vault perforation. When a perforation does occur, the suprascapular nerve appears to be at high risk for injury especially with more posterior drill holes. The risk is significantly higher in females and in smaller scapulae.

Timothy H. Bell Graham J.W. King James A. Johnson Louis M. Ferreira Colin P. McDonald

Purpose: The purpose of this study was to determine the effect of serial olecranon resections on elbow stability.

Method: Eight fresh, previously frozen cadaveric arms underwent CT scanning. The specimens were mounted in an in-vitro motion simulator, and kinematic data was obtained using an electromagnetic tracking system. Simulated active and passive flexion was produced with servo-motors and pneumatic pistons attached to specific muscles. Flexion was studied in the dependent, horizontal, varus, and valgus positions. Custom computer navigation software was utilized to guide serial resection of the olecranon in 12.5% increments. A triceps advancement repair was performed following each resection.

Results: Serial olecranon resections resulted in a significant increase in valgus-varus (V-V) laxity for both passive (p< 0.001) and active (p=0.04) flexion. For passive motion this increase reached statistical significance following the 12.5% resection. This corresponded to an increase in V-V laxity of 1.4 ± 0.1o and a total laxity of 7.5 ± 1.0o. For active flexion this increase reached significance following the 62.5% resection. This corresponded to an increase in V-V laxity of 5.6 ± 1.1o and a total laxity of 11.2 ± 1.5. There was no significant effect of sequential olecranon excision on elbow kinematics or stability with the elbow in the vertical or horizontal positions. The elbows became grossly unstable after resection of greater than 75% of the olecranon.

Conclusion: A progressive increase in the varus-valgus laxity of the elbow was seen with sequential excision of the olecranon. Laxity of the elbow was increased with excision of 75% of the olecranon, likely due to the loss of the bony congruity and attachment site of the posterior band of the medial collateral ligament. Gross instability resulted when 87.5% or greater was removed, likely due to damage to the anterior band of the medial collateral ligament as it inserts on the sublime tubercle of the ulna. Rehabilitation of the elbow with the arm in the dependant position should be considered following excision of the olecranon; varus and valgus orientations should be avoided. The contribution of the olecranon to elbow stability may be even more important in patients with associated ligament injuries or fractures of the elbow.

R. Cole Beavis F. Alan Barber Morley A. Herbert

Purpose: To evaluate the insertion forces required to seat osteochondral plug grafts and the accuracy of plug harvest and seating using three unique instrumentation systems. Our hypothesis was that the systems would have different insertion forces.

Method: The COR (Depuy-Mitek), Mosaicplasty (Smith & Nephew) and OATS (Arthrex.) Instrumentation systems and recommended surgical techniques were used to harvest, transfer, and implant grafts. To simulate the in-vivo surgical setting, multiple-impacts with a mallet were applied to the instruments. Ten tests each were performed for all systems in both rigid polyurethane foam blocks and porcine femur models. Plug length after harvest and final graft position were manually measured. Insertion forces were recorded using a load cell (Omega Engineering) affixed to the insertion tamp. The area under the force curve recorded by the transducer for each blow was then summed to yield the total force required to seat each graft. Means and standard deviations were then calculated and Tukey’s test was used to determine significant differences between the means.

Results: The COR system demonstrated significantly lower mean insertion forces in both polyurethane foam blocks and porcine models when compared with the OATS and Mosaicplasty systems. Graft harvest with Mosiacplasty led to greater harvest length inconsistency than with other systems tested. OATS grafts were more likely to be left proud.

Conclusion: The COR system produced significantly lower insertion forces during graft insertion. COR and OATS yielded consistent harvest lengths. The majority of OATS grafts were left proud which would require additional impaction force to fully seat the graft.

J Whitcomb Pollock James R. Browhill Louis Ferreira Colin P. McDonald James Johson Graham J.W. King

Purpose: The role of the posterior bundle of the medial collateral ligament (PMCL) in stability of the elbow remains poorly defined. The purpose of this study was to determine the effect of sectioning the PMCL on the stability of the elbow.

Method: Varus and valgus gravity-loaded passive elbow motion and simulated active vertical elbow motion were performed on 11 cadaveric arms. An in-vitro elbow motion simulator, utilizing computer-controlled pneumatic actuators and servo-motors sutured to tendons, was used to simulate active elbow flexion. Varus/valgus angle and internal/external rotation of the ulna with respect to the humerus were recorded using an electromagnetic tracking system. Testing was performed on the intact elbow and following sectioning of the PMCL.

Results: With active flexion in the vertical position the varus/valgus kinematics were unchanged after PMCL sectioning (p=0.08). However, with the forearm in pronation, there was a significant increase in internal rotation after PMCL sectioning compared to the intact elbow (p< 0.05) which was most evident at 0° and 120° degrees of flexion (p< 0.05). This rotational difference was not statistically significant with the forearm in supination (p=0.07). During supinated passive flexion in the varus position, PMCL sectioning resulted in increased varus angulation at all flexion angles (p< 0.05). In pronation varus angulation was only increased at 120° of flexion (p< 0.05). However, internal rotation was increased at flexion angles of 30° to 120° (p< 0.05). In supination, sectioning the PMCL had no significant effect on maximum varus-valgus laxity or maximum internal rotation (p=0.1). However, in pronation, the maximum varus-valgus laxity increased by 3.5° (30%) and maximum internal rotation increased by 1.0° (29%) (p< 0.05).

Conclusion: These results indicate that isolated sectioning of the PMCL causes a small increase in varus angulation and internal rotation during both passive varus and active vertical flexion. This study suggests that isolated sectioning of the PMCL may not be completely benign and may contribute to varus and rotation instability of the elbow. In patients with insufficiency of the PMCL appropriate rehabilitation protocols (avoiding forearm pronation and shoulder abduction) should be followed when other injuries permit.

Sean Haslam Daniel P. Borschneck

Purpose: The purpose of this study was two-fold. First, we wanted to compare the cost of liquid waste disposal from the operating rooms (ORs) via a 3rd party medical waste company, with utilization of the sewer system at Kingston General Hospital. Secondly, we sought to assess national trends in liquid waste disposal, in order to make a national recommendation for liquid waste disposal from the OR.

Method: The hospital cost for OR liquid waste disposal at Kingston General Hospital was calculated by weighing the liquid waste from 871 surgical cases over a 5-week period in 2008. The materials, manpower and weight of the waste were used to calculate the costs for the two methods of liquid waste disposal. Seventy teaching hospitals across Canada were surveyed to determine their practice of liquid waste disposal in the OR.

Results: The raw cost per kg of liquid waste disposal using a medical waste company was found to be 57.126 % greater than utilizing the sewer system. Using the sewer system resulted in a total cost reduction of 40% compared with using a medical waste company. Sixty-three out of seventy teaching hospitals across the nation (90%) were found to utilize medical waste companies, while seven out of seventy hospitals (10%) utilized the sewer system to dispose of liquid waste.

Conclusion: The sewer system is an under-utilized yet safe, legal, and cost effective way to dispose of liquid waste from the OR. Using the sewer system to dispose of liquid waste would save the Canadian health care system millions of dollars compared with disposal via medical waste companies.

Michael G. Zywiel Slif D. Ulrich Arnold D. Suda James L. Duncan Mike S. McGrath Michael A. Mont

Purpose: Many strategies have been reported for decreasing the cost of orthopaedic procedures, including negotiating lower prices with manufacturers and using lower-cost generic implants, but prosthetic waste has not been investigated. The purpose of this study was to characterize the present and potential future cost of intra-operative waste of hip and knee implants.

Method: A regional prospective assessment of implant waste was performed from January 2007 to June 2008, evaluating the incidence and reasons for component waste, the cost of the wasted implants, and where the cost was absorbed (hospital or manufacturer). Using published data on nationwide arthroplasty volumes, the results were extrapolated to the whole of the United States. Finally, based on peer-reviewed estimates of nationwide arthroplasty volumes for the next 20 years, a projection was made about the future cost burden of implant waste.

Results: Implant waste occurred in 79 of 3443 recorded procedures (2%), with the surgeon bearing primary responsibility in 73% of occurrences. The annualized waste cost was $109,295.35, with 67% absorbed by the hospital. When extrapolated to the whole of the United States, the annual cost to hospitals of hip and knee prosthetic waste is $36,019,000, and is estimated to rise to $112,033,000 in current dollars by the year 2030.

Conclusion: This study discovered a notable incidence of intra-operative hip and knee implant waste, with the majority of cases attributed to the surgeon, and representing an important additional cost burden on hospitals. With arthroplasty rates projected to increase markedly over the next twenty years, this waste represents a potentially noteworthy target for educational programs and other cost containment measures in orthopaedic surgery.

Dominique Rouleau George Athwal Kenneth J. Faber

Purpose: Recognition of the proximal ulna dorsal angulation (PUDA) is important for anatomic reduction of proximal ulnar fractures or osteotomies, especially when using newer straight precontoured proximal ulnar plates. The purpose of this study was to characterize the PUDA in 50 patients with bilateral elbow radiographs.

Method: Bilateral elbow radiographs (100 radiographs) were magnified four times using commercial software. The PUDA was measured from the intersection of lines tangent to the subcutaneous border of the olecranon and the proximal ulnar shaft. The olecranon tip-to-apex distance of the PUDA was also measured. Three orthopaedic surgeons independently examined the radiographs and intra/inter-observer reliability was calculated using Intra-Class-Correlation (ICC).

Results: A PUDA was present in 96% of radiographs. The average PUDA was 5.7° (range, 0°to14°). The Pearson Correlation coefficient for a side-to-side comparison was 0.86(p< 0.001). The average tip-to-apex distance was 47 mm (34 mm–78mm). No correlation was identified with sex or age. Intra-observer reliability was excellent for the PUDA (ICC 0.892 and 0.863) and good for tip-to-apex distance (ICC 0.762 and 0.827). Inter-observer reliability was good for PUDA (ICC 0.784 and 0.925) and for tip-to-apex distance (ICC 0.711 and 0.769).

Conclusion: A mean proximal ulna dorsal angulation of 5.7° is present in 96% of patients at an average of 47 mm distal to the olecranon tip. Measurement of the PUDA has good/excellent inter/intra-observer reliability. Recognition of the PUDA may be helpful in anatomic plating of the ulna. Contralateral PUDA measurements are useful for surgical planning in cases with comminution or distorted anatomy.

Peter Zarkadas Ben Cass Thomas Throckmorton Robert Adams Joaquin Sanchez-Sotelo Bernard F. Morrey

Purpose: Resection elbow arthroplasty is a salvage procedure typically considered as a last resort when other reconstructive options have failed. It was the intent of this study to evaluate the long-term outcome of patients following resection elbow arthroplasty.

Method: Fifty-four elbow resections performed between 1975 and 2005 were retrospectively reviewed. Pre and post-operative elbow function was evaluated with the Mayo Elbow Performance Score (MEPS) and additional follow-up data was compiled using the Disability of Shoulder and Hand (DASH) score. All patients in this study had a resection following a failed total elbow arthroplasty (TEA). Nineteen patients had died at time of follow-up, and 5 patients were lost to follow-up, leaving 30 of the surviving 34 patients (88%) available for long-term evaluation.

Results: The main indication for resection in this study was infection (50 of 54 elbows). The average MEPS prior to resection was 36. The long-term results in 30 patients at an average of 11 yrs (range 2.7–28 yrs) demonstrated an average MEPS score of 60, and a DASH score of 71. Complications were common including persistent infection requiring re-operation (44%), intra-operative fracture (32%), transient (11%) or permanent (5.5%) nerve damage, and one case of vascular injury requiring amputation. Achieving a stable resected elbow correlated strongly with a good long-term MEPS score (r=0.75).

Conclusion: This study emphasizes the difficulty in treating patients with a failed total elbow arthroplasty. Resection arthroplasty is a salvage procedure indicated primarily for persistently infected TEA and results in satisfactory outcomes in this population.

Nyagon G. Duany Michael G. Zywiel Mike S. McGrath Junaed A. Siddiqui Lynne C. Jones Michael A. Mont

Purpose: Spontaneous osteonecrosis of the knee is a potentially greatly debilitating condition. While success has been reported with non-operative treatment of this disorder in its earliest stages, knee arthroplasty is the only viable modality if allowed to progress to condylar collapse. The purpose of this report is to review the etiologic and pathophysiologic principles of spontaneous osteonecrosis of the knee, to present our experience with joint-preserving surgical treatment of this condition, and finally to introduce a treatment algorithm developed based on this knowledge.

Method: Seventeen patients with a clinical and/or radiographic a diagnosis of spontaneous osteonecrosis of the knee, and exclusion of secondary osteonecrosis, who failed non-operative modalities were treated with joint-preserving surgery at a single center between January 2000 and December 2006. Treatment modalities included arthroscopy, and either percutaneous core decompression and/or osteochondral autograft transfer. Three knees were lost to follow-up, leaving 14 knees with a mean follow-up of 37 months (range, 11 to 84 months).

Results: Twelve of 14 knees (86%) had knee joint survival with a mean Knee Society Score of 80 points (range, 45 to 100 points) at final follow-up. One patient was treated with serial core decompression followed by osteochondral transfer, and was included in both groups. Six of 7 patients (86%) treated with core decompression alone had a successful clinical outcome, as did 7 of 8 patients (87%) treated with osteochondral autograft transfers. Two patients (14%) progressed to condylar collapse, and were treated with total knee arthroplasty with successful results.

Conclusion: Based on these results, we propose a treatment algorithm that begins with non-operative treatment, followed by joint-preserving surgery consisting of arthroscopy, core decompression, and/or osteochondral autograft transfer. Although our sample size is small, the results suggest that this proposed treatment algorithm can successfully postpone the need for knee arthroplasty in selected patients with pre-collapse spontaneous osteonecrosis of the knee.

Carol R. Hutchison Claude Martin

Purpose: Litigation continues to be a concern in orthopaedic surgery despite suggestions on how to contain liability. The purpose of this study was to characterize orthopaedic litigation in Canada from 1997–2006.

Method: This study reviewed all closed claims reported to the Canadian Medical Protective Association (CMPA) for 1997–2006 in which orthopaedic surgeons were named. There were 11,983 closed legal actions involving CMPA members (> 73,000 physicians), and 1,353 involved orthopaedic surgeons. A careful review of closed legal actions is a recognized tool for risk identification, assessment and management. The CMPA identifies any critical incidents within the closed legal files. A critical incident is defined as any omission or commission in the evaluation or management which led to the problem(s) that triggered the legal action. Each closed legal action can have more than one critical incident.

Results: Performance, diagnostic and communication issues were the most frequently identified problems. These three areas account for 55% of the critical incidents identified. Performance related issues accounted for 395 critical incidents (29%). Diagnostic issues, including deficient histories and general evaluations, were identified in 281 cases (21%). Communication-related critical incidents included those concerning informed consent. The lack of informed consent was a common allegation, proven in 71 cases. In 439 cases (32%) there was no identifiable critical incident for the orthopaedic surgeon involved. Seventy-eight per cent of patients experienced minor or no disability and 22% experienced major disability or death. Events related to tibia trauma and knee arthroscopy formed the two major categories of claims. Patient care areas of high risk include the operating room and outpatient clinic. Overall, 31% of legal actions against orthopaedic surgeons had outcomes in favour of the plaintiffs, compared with 33% of all CMPA members’ claims.

Conclusion: Although the likelihood for an orthopaedic surgeon to be sued in Canada has decreased over the last 10 years, the percentage of legal cases resolved in favour of plaintiffs has remained stable. Performance-related deficiencies, delays in diagnosis, and failures in communication represent areas of high medico-legal risk. Suggestions for risk management are provided to further decrease adverse events and the medico-legal risks for Canadian orthopaedic surgeons.

Yangmin Zeng Travis Marion Pamela Leece Eugene Wai

Purpose: Persistent radiculopathy secondary to lumbar disc herniation is a common problem that greatly compromises quality of life. In North America, lumbar discectomies are among the most common elective surgical procedures performed. There is still much debate about when conservative or surgical treatments should be offered to patients. Although the related literature is comprehensive, there are limited systematic reviews on the prognostic factors predicting the outcome of lumbar discectomy. The purpose of this review is to define the preoperative factors predicting clinical outcome after lumbar discectomy.

Method: We conducted a computerized literature search using Ovid Medline and the Cochrane Central Register of Controlled Trials. We included randomized controlled trials or prospective studies dealing with lumbar disc surgery. The preoperative predictors had to be clearly identified and correlated with outcome measures in terms of pain, disability, work capacity, analgesia consumption, or a combination of these measures. We assessed the articles as high or low quality studies using the Newcastle-Ottawa Quality Assessment Scale, and summarized the results of High Quality Studies.

Results: A total of 39 articles were included. The two most prominent negative predictors were Workers’ Compensation status and depression according to 6 studies. Poor predictors reported in 4 articles were female gender, increasing age, and prolonged duration of leg or back pain. Lower education level, smoking, and higher levels of psychological complaints were negative predictors in 3 articles. A positive Lasègue sign was a positive predictor in 7 articles. Absence of back pain, positive patient expectations, and higher income were good prognostic factors in 3 studies. Patients with contained herniations did worse than those who had uncontained disc extrusions and sequestrations according to 4 studies. The level of herniation was not a predictive factor in 7 studies.

Conclusion: Workers’ Compensation, depression, greater back versus leg pain, increasing age, female gender, contained herniations, and prolonged symptoms predict unfavourable postoperative outcomes after lumbar discectomy. Positive Lasègue sign, higher income, uncontained herniations, and positive patient expectations predict favourable postoperative outcomes. The level of herniation is not an established prognostic factor. The results of this review provide a preliminary framework for patient selection for lumbar disc surgery.

John M. Froelich Joseph C. Milbrandt D. Gordon Allan

Purpose: The current study examines the impact of the 80-hour work week on the number of surgical cases performed by PGY2 – PGY5 Orthopedic residents. We also evaluated Orthopaedic In-training Exam (OITE) scores during the same time period.

Method: Data were collected from the ACGME national database for 3 academic years prior to and 5 years after July 1, 2003. CPT surgical procedure codes logged by all residents three years prior to and five years following implementation of the 80-hour work week were compared. The average raw OITE scores for each class obtained during the same time period were also evaluated. Data were reported as the mean ± standard deviation (SD) and group means were compared using independent t-tests.

Results: No statistical difference was noted in the number of surgical procedure codes logged prior to or after institution of the 80-hour week during any single year of training. However, an increase in the number of CPT codes logged in the PGY-3 year after 2003 did approach significance (457.7 vs. 551.9, p=0.057). There was a statistically significant increase in total number of cases performed (464.4 vs. 515.5 p=0.048). No statistically significant difference was noted in the raw OITE scores before or after work hour restrictions for our residents or nationally.

Conclusion: We found no statistical difference for each residency class in the average number of cases performed or OITE scores. We also found no statistical difference in the national OITE scores. Our data suggest that the impact of the 80 hour work has not had a detrimental effect in these two resident training measurements.

Travis E. Marion Yangmin Zeng Eugene Wai

Purpose: Perispinal core muscle strength has been theorized to be an important component in the pathogenesis of back pain. Recent research has demonstrated a strong association between preoperative perispinal musculature, adjusted for fatty infiltration and prospective outcomes and improvements in back pain in patients undergoing lumbar laminectomy without fusion. The purpose of this study is to determine if a similar relationship exists in patients undergoing elective posterior lumbar fusion and decompression (PLFD) surgery.

Method: A retrospective observational study of prospectively collected outcomes data was conducted in which pre-operative function and patient variables of those undergoing PLFD were derived from a functional status questionnaire and medical records. ImageJ Digital Imaging Software was utilized to measure the total (CSA) and percentage of fatty infiltration of the psoas, multifidus, and erector spinae muscles in pre-operative L4 axial CT images. Pre-operative and post-operative lateral images were evaluated for degree of post-operative adjacent level degeneration. Follow-up consisted of a functional status questionnaire. Outcomes measured were improvements in back pain, leg pain, and Oswestry disability scores.

Results: Twenty-three patients were analyzed with a mean follow-up of 2 years (range 1 – 5 years). Outcomes improved following surgery. There were strong to moderate correlations between percentage of fat in the pre-operative posterior spinal muscles and improvements in leg pain (r = 0.63, p = < 0.001) and improvements in back pain (r = 0.41, p = 0.05). There was a moderate trend towards greater adjacent level degeneration (r = 0.37, p = 0.1) in patients with higher percentage of fat in the pre-operative posterior spinal muscles. There was a strong relationship between greater adjacent level degeneration and pre-operative disability as measured by the Oswestry (r = 0.62, p = 0.03).

Conclusion: The results demonstrate that a potential relationship exists between pre-operative fatty infiltration of posterior perispinal muscles and post-operative outcomes, and adjacent level degeneration following lumbar fusion surgery. This suggests that perispinal muscle atrophy and conditioning may play a role in these outcomes. Results may be used for prognostication, surgical candidate selection, and interventional strategies.

Girish N. Swamy Lynn DeLoughery Rajendranath Bommireddy Zdenek Klezl Denis Calthorpe

Purpose: The management of radicular pain due to lumbar or sacral nerve root compromise remains controversial. Caudal epidural steroid injections are widely employed although there is little hard evidence to confirm their efficacy. This empirical treatment still remains a matter of personal choice and experience. To investigate the clinical effectiveness of caudal epidural steroid injections (CESIs) in the treatment of sciatica and to identify potential predictors (clinical subgroups) of response to CESIs.

Method: Prospective study. All patients with corresponding radicular pain received a course of three caudal epidural steroid injections, two weeks apart. All patients reviewed at three months interval in a dedicated epidural follow up clinic and one-year postal and telephonic follow-up. Exhaustive epidural database maintained. VAS scores documented both axial and limb pain for actual and comparative analysis. ODI and HADS were recorded prior to treatment, at three months follow-up and one year. Main outcome measures: The primary outcome measure was the Oswestry Disability Questionnaire (ODQ). The Visual analogue score (VAS) and the Hospital Anxiety and Depression Scores (HADS) were also employed in all cases.

Results: In the largest single series to date, we report on 928 consecutive patients, with three months follow-up and 354 patients with 12 months follow-up. Fifty-eight percent were females, 24% smoked and 4.1% had ongoing litigation due to their pain. The mean age was 56 years with BMI ranging from 17 to 50 (mean=28). Ten (0.6%) patients required subsequent surgical intervention due to disc herniation. The mean VAS, ODI and HADS improved significantly at three months and one-year results were encouraging.

Conclusion: Significant improvement in both axial and limb pain in the short and intermediate terms achieved facilitating onward referral for physical therapy. Subgroups predicting poor outcome are identified. Positive primary care feedback encourages further recruitment.

Michael Katsimihas Christopher Bailey Khalil Issa Stuart I. Bailey Jennifer Fleming Patricia Rosas-Arellano Kevin R. Gurr

Purpose: To report the clinical and radiographic prospective results of a consecutive series of patient with a minimum two year follow-up with the Charite Total Disc Arthroplasty (TDA).

Method: Between 2001 and 2005, sixty patients underwent a Charite TDA (Depuy Spine, Raynham, MA) at either L4-5 or L5-S1. The primary indication for surgery was discogenic low back pain confirmed by provocative discography. Clinical assessment was carried out preoperatively and postoperatively at 3, 6, 12 months, and once a year thereafter using the Oswestry Disability Index (ODI), Visual Analogue Scale (VAS) for back and leg pain, and SF-36. Radiographic analysis included: angle of sagittal rotation, translation of the rostral vertebra onto the caudal vertebra, anterior vertical motion (AVM), middle vertical motion (MVM), posterior vertical motion (PVM), pre- and post-operative lumbar lordosis, disc height and subsidence of the TDA. The radiographic measurements were performed using the GE Medical Systems Centricity PACS Software Version 1.0.

Results: There were 36 female and 24 male patients with a mean age of 39 (range 21–59). The mean duration of low back pain was 70 months. Twenty-five percent claimed work compensation status. The mean postoperative hospital stay was 4.8 days. A statistical significant improvement was demonstrated between the mean pre-operative ODI (50) and all post-operative intervals (p< 0.0001) which had declined to 27.7 by one year. Similarly, pre-operative VAS back pain (8.0), leg pain (6.1), SF-36 physical component summary score (33.5) and mental component summary score (41.8) remained improved (p< 0.0001) by three months (4.1, 3.1, 51.7, 62.0 respectively). One patient with an L5-S1 TDA has since undergone a posterolateral instrumented fusion. The mean pre- and post-operative lumbar lordosis was 34.58 and 53.48 respectively. The mean saggital rotation was 6.5 degrees at 5 year follow-up, while the mean translation was 0.83 mm. The mean AVM, MVM and PVM were 0.59 mm, −3.96 mm and 3.69 mm respectively at 5 year follow-up.

Conclusion: This study demonstrates satisfactory clinical results in carefully selected patients. The radiographic assessment confirmed preservation of movement at the replaced disc during flexion and extension of the lumbar spine.

Bernard E. Rerri Temilolu O. Opadele

Purpose: Lumbar spinal stenosis is the most common indication for spine surgery in the elderly. XStop IPD is an attractive alternative to traditional laminectomy or laminectomy with fusion as it avoids a longer procedure and anaesthesia with significantly less blood loss. The purpose of this study is to prospectively evaluate clinical outcomes, complications and functional evaluation of symptom severity, physical function and patient satisfaction following XStop IPD procedure

Method: Preoperative and postoperative clinical data as well as SF 36, visual analog scale and Roland Morris questionnaire data collected on 16 consecutive patients over 60 years undergoing XStop IPD at L3-4 and L4-5 levels or both levels. All patients had symptomatic lumbar spine stenosis with intermittent neurogenic claudication. Evaluations were made pre-operatively and post-operatively at 3, 6, 12 and 24 months. All patients had clinical radiographic data as well as data on visual analog scale SF 36 and the Roland Morris back questionnaire.

Results: Patients ages ranged from 58 to 86 years with an average age of 74.25 years. In 75 percent of patients there were two or more significant co-morbidities with 18.75 percent requiring 2 level surgery. Four of the 16 patients had lumbar degenerative scoliosis with cobb angle less than 25 degrees. 50.25% the patients had grade I spondylolisthesis. No patient had previous spine surgery. In 31.25 percent of patients there was a history of diabetes. BMI ranged from 20 to 40. Seventy five percent of patients were discharged home within 24 hours. Ninety percent of patients reported relief of their leg pain at their first follow up visit within two weeks of the surgery. There were no significant complications. One-year follow up in six patients demonstrated improvements in VAS, Roland Morris criteria and SF 36 while the remaining patients have up to nine months of follow-up clinical data.

Conclusion: We present our early results of this prospective study. There were significant improvements in functional outcomes. We therefore recommend the use of XStop IPD for elderly patients with multiple co-morbidities suffering from symptomatic lumbar spine stenosis with neurogenic claudication.

S. Samuel Bederman Nizar N. Mahomed Hans J. Kreder Warren J. McIsaac Peter C. Coyte James G. Wright

Purpose: Surgery for degenerative lumbar spinal conditions offers tremendous benefit for patients with moderate/severe symptoms failing non-operative treatment. There is little appreciation among referring family physicians (FPs) on factors that identify the ideal surgical candidate. Differences in preferences between patients and physicians leads to wide variation in referrals and impedes the shared decision-making process. Our purpose was to identify the dominant clinical factors influencing patient, FP, and surgeon preferences for lumbar spinal surgery.

Method: We used conjoint analysis, a rigorous method for eliciting preferences, in a mailed survey to all orthopaedic and neurosurgeons, a random sample of FPs, and patients in Ontario to determine the importance that respondents place on decisions for lumbar spinal surgery. We identified six clinical factors (walking tolerance, duration of pain, pain severity, neurological symptoms, typical onset, and dominant location of pain) and presented 16 hypothetical vignettes to participants who rated, on a six-point-scale, their preference for surgery. Data were analyzed using random-effects ordered probit regression models and relative importance of each clinical factor was reported.

Results: We obtained responses from 131 surgeons, 202 FPs, and 164 patients. We demonstrated that despite wide variations in overall responses, all six clinical factors were highly associated with surgical preference (p< 0.01). Surgeons placed the highest importance on the location of pain (34%), followed by pain severity (19%) and walking tolerance (19%). FPs considered neurological symptoms (23%), walking tolerance (20%), pain severity (20%), and typical onset (16%) to all be of similar importance. Pain severity (29%), walking tolerance (29%), and duration of pain (28%) were the most important factors for patients in deciding for surgery. Orthopaedic (over neurosurgical) specialty was statistically associated with a lower preference for surgery (p< 0.047). Older patient age (p< 0.03) and previous surgical consultation (p< 0.03) were both associated with a greater patient preference for considering surgery.

Conclusion: Different preferences for surgery exist between surgeons, FPs and patients. FPs may reduce over- and under-referrals by appreciating surgeons’ importance on location of pain (leg versus back). Surgeons and FPs may improve the shared decision making process by understanding that patients place high importance on duration, severity, and walking tolerance.

Michael Katsimihas Christopher Bailey Ashley Ignatiuk Patricia Rosas-Arellano Stuart I. Bailey Khalil ssa Kevin R. Gurr

Purpose: To investigate subsidence of the Charite total disc arthroplasty (TDA) and to identify if a discrepancy between vertebral endplate and the Charite footprint predispose to subsidence.

Method: Between July 2001 and May 2008, 69 patients underwent a Charite TDA (DePuy Spine, Raynham, MA). They were prospectively followed at 3, 6, 12 months, and once a year thereafter. The following measurements were performed on the replaced motion segment using a lateral radiograph:

The anterior-posterior (AP) dimension of the end plates.

Amount of subsidence.

The distance between the TDA and the posterior and anterior borders of the vertebra bodies (to represent the extent of uncoverage of the endplate by the TDA).

The AP dimension of the TDA metal end-plate.

The ratio between the actual and radiographic AP length of the metal endplate was calculated and utilized as the correction factor for the error of magnification on all other radiographic measurements.

Results: At L5-S1 the mean subsidence was 1.87 mm and occurred exclusively at the posterior part of the inferior end plate of L5. The mean posterior uncoverage was 3.5 mm (L5) and 0.27mm (S1). At L4-L5 the mean subsidence was 1.48 mm (L4) and 0.56 mm (L5). Posterior uncoverage of L4 and L5 vertebrae were 4.81 and 2.22 mm, respectively. Subsidence of more than 1 mm was present in all cases where the posterior uncoverage of the end plate with the TDA was more than 2 mm (odds ratio: 5.7). Subsidence was non – progressive in all cases. An anatomic mismatch exists between L5 and S1 endplates in the AP dimension; in more than half the patients S1 is shorter than L5.

Conclusion: The radiographic measurements suggest an increased likelihood of subsidence with more than 2 mm of posterior uncoverage of the end plate by the TDA. The endplate AP length of S1 is frequently less than that of L5. Implant selection based on the smaller S1 endplate may produce worrisome uncoverage of the L5 inferior endplate leading to an increased risk of subsidence and possible catastrophic failure. TDA design should afford modularity to compensate.

David I. Alexander William M. Oxner Alex M. Soroceanu Adrienne Kelly Donna Shakespeare

Purpose: The current gold standard for spinal arthrodesis, autologous bone graft harvested from the iliac crest, has several disadvantages including donor site morbidity, blood loss, delayed wound healing, and increased operative time. Our study explores a Demineralized Bone Matrix-Calcium Sulfate(DBM-CaSO4) composite graft with autologous bone marrow aspirate (BMA), and compares it to autologous iliac crest bone graft in lumbar and lumbosacral spinal fusions.

Method: A total of 80 patients were recruited for the study and randomised, via a computer-generated ran-domisation schedule, to autologous iliac crest bone graft (control) or DBM-CaSO4 composite graft with BMA (study) groups. Patients were evaluated at three-months, six-months, 12-months and 24-months post-operatively with questionnaires to evaluate clinical outcome (Oswestry disability questionnaire (ODI), visual analogue pain scales (VAS), and validated SF-36) and with posteroanterior and lateral x-rays of the spine to evaluate radiological outcome.

Results: At 24-months post-operatively, there were no statistical differences seen between the two groups based on the clinical outcomes measured. Average ODI values were 27.19 for the control group versus 22.68 for the study group (p > 0.05). The average back VAS pain for the control group was 3.50 versus 3.51 for the study group (p > 0.05). The SF-36 score was 89.22 for the control group versus 91.56 for the study group (p > 0.05). The average operative time was 115.7 minutes for the control group versus 104.2 minutes for the study group (p: 0.014). Average calculated blood loss was 571.9 cc for the control group versus 438.2 cc for the study group (p: 0.025). The Lenke score was 1.92 for the control group versus 2.66 for the study group (p: 0.004).

Conclusion: At two year follow-up, radiographic fusion was slightly higher in the ICBG. However, clinical outcomes were equivalent in both groups. Moreover, the DBM-CaSO4 and BMA composite graft offered the advantages of decreased blood loss and shorter operative time. Therefore, the DBM-CaSO4 and BMA composite graft represents a viable alternative to autologous iliac crest bone graft in carefully selected patients undergoing spinal arthrodesis.

Davor D. Saravanja Charles G. Fisher Marcel Dvorak Michael Boyd Paul Clarkson

Purpose: Oncologic management of primary bone tumors of the spine is inconsistent, controversial and open to individual interpretation. Tumor margin violation intraoperatively increases local recurrence and mortality. The purpose of this study is to determine whether applying Enneking’s principles to the surgical management of primary bone tumors of the spine significantly decreases local recurrence and/or mortality.

Method: A prospective and retrospective multicenter Cohort Study: Inclusion of patients undergoing en bloc or intralesional resection of primary tumors of the spine at four separate quaternary care centers, between January 1994 and January 2008. Patients were staged, using the Enneking system, prior to surgery and baseline demographic and surgical variables were recorded. Outcomes measured were disease local recurrence, or death. The results were statistically analyzed for significance.

Results: One hundred-fifty patients with primary tumors of the spine were recruited. Average age was 47.0 (range 8 to 83). Sixty-two patients were identified to have local recurrence. A statistically significant decrease in local recurrence (p=0.0001) was observed in favor of en bloc resection. In patients with local recurrence there was a significant increased risk of mortality, (p< 0.0001). There was a trend to decreased mortality in the en bloc resection group, not statistically significant (p=0.64).

Conclusion: Wide resection of primary tumors of spine with reconstruction is the standard of care. Application of Enneking’s principles to the spine when managing primary bone tumors significantly reduces local recurrence of the disease process, without an adverse outcome on mortality, and with acceptable HRQOL. Further cohort studies based on stringent data collection prospectively will provide a basis for more detailed study of individual tumor types.

Martin Lavigne Pascal-André Vendittoli

Purpose: The long term exposure to metal ions released from metal-metal articulations is worrying. Studies have shown comparable ion level between metal-metal HR and 28mmTHA. No study has analyzed the amount of ion released from LDH-THA. We compared the amount of ion released from HR and LDH-THA from the same manufacturer.

Method: Whole-blood concentrations of Cobalt was measured prospectively (pre op, 3, 6, 12, 24 months) with HR-ICPMS in 74 HR and 54 LDH-THA with the same metal bearing characteristics and acetabular component (monoblock Cobalt-Chrome with titanium plasma-spray coating). The femoral head of LDH-THA was inserted on a titanium stem with a Cobalt-Chrome adapter sleeve to adjust offset and leg length.

Results: Demographic data was similar. The pre op Cobalt level (ug/L) were 0.10 vs. 0.11, 3 months 0.90 vs. 0.84, 6 months 0.90 vs. 1.28, 12 months 0.68 vs.1.75, and 24 months 0.56 (5.6X preop level) vs. 1.82 (16.5X preop level) in the HR and LDH-THA groups, respectively. The cobalt level decreased after 6 months in HR, whereas it was still increasing at 2y with LDH-THA.

Conclusion: In order to reduce wear and ion release from metal-metal bearing, most manufacturers focus research on improvements at the bearing surfaces. This study has shown that the simple addition of a sleeve with 2 modular junctions can results in a dramatic increase in ion release, diminishing the value of improvements made at the bearing surface. The total amount of ion released from a metal-metal implant should be considered globally and as such, better modular taper designs should be developed.

John Townley Cari Whyne Michael R. Hardisty Liying Zhang Mark Clemons Albert J.M. Yee

Purpose: To identify local and systemic risk factors for the development of pathologic fractures and determine the value of the Tokuhashi Score in patients with known asymptomatic lytic spinal metastases secondary to breast cancer.

Method: A prospective cohort study was carried out on 51 patients with lytic spinal metastases secondary to breast cancer identified as having either purely lytic or mixed disease. The Tokuhashi Score, developed to estimate life expectancy for patients with symptomatic spinal metastases being considered for surgery, was calculated for each of the 51 patients. The score consists of six parameters each of which is rated from 0–2. Initial and follow up CT images and pain and function data were obtained every four months for one year. A final review of patient charts was performed two years later to determine if each patient was still alive.

Results: Tumour burden was predominantly blastic and mixed rather than lytic. There was no progression of lytic tumour burden over the 12-month period, however there was progression of blastic tumour load. Eleven compression fractures occurred in seven patients; no burst fractures occurred during the study. No correlation between tumour burden (lytic, blastic or both) and risk of fracture was found. A weak correlation between bone mineral density and length of time elapsed from diagnosis of metastatic disease and fracture risk was found. Pain and functional data results were not related to tumour load. Tokuhashi score did correlate with survival, however actual survival in our population was far longer than that found in previous studies. Negative progesterone status was found to be negatively associated with life expectancy.

Conclusion: Metastatic vertebral disease in breast cancer patients has a predominantly blastic and mixed appearance with current pharmacologic therapies. Pathologic fracture risk appears to be more related to bone mineral density than tumour burden in this population. Tokuhashi score does correlate with life expectancy in patients with relatively asymptomatic spinal metastases. Having a progesterone receptor negative tumour has a significantly negative impact on life expectancy.

Steven J.M. MacDonald C. Anderson Engh Abigial E. Thompson Supatra Sritulanondha Douglas Naudie Charles A. Engh

Purpose: Metal-on-metal articulations are an increasingly popular choice as an alternate bearing surface in total hip arthroplasty (THA) and Resurfacing implants. One advantage of a metal-on-metal bearing is the use of larger diameter femoral heads with hip simulator data demonstrating reduced wear. We performed a prospective, multicentre, randomized, blinded clinical trial comparing 28mm to 36mm metal-on-metal bearings assessing multiple validated outcome measures and serum, erythrocyte and urine metal ions.

Method: Ninety-one patients were randomized to receive a metal-on-polyethylene (34), a 28mm metal-on-metal (25) or a 36mm metal-on-metal (32) insert. All patients received the same acetabular and femoral component. Patients were evaluated pre-operatively, at 6, 12 months and annually thereafter, including an evaluation of serum, erythrocyte and urine cobalt, chromium, and titanium, outcome measures (WOMAC, SF-12, Harris Hip Score) and radiographs.

Results: At a minimum two years follow-up there were no differences in WOMAC, SF-12, Harris Hip scores or radiographs. Patients receiving metal liners had significantly (p< 0.001) elevated metal ion measurements compared with the polyethylene control group, however there were no differences between the 28mm and 36mm metal-on-metal bearings (Median serum Co (mg/L): 0.14(poly), 0.77(28mm), 0.73(36mm). Median erythrocyte Co (mg/L): 0.11(poly), 0.42(28mm), 0.42(36mm). Median urine Co(mg/day): 0.44(poly), 4.55(28mm), 5.42(36mm)). (Median serum Cr(mg/L): 0.17(poly), 1.29(28mm), 0.91(36mm). Median erythrocyte Cr(mg/ L): 1.10(poly), 1.10(28mm), 1.20(36mm). Median urine Cr(mg/day): 0.27(poly), 1.92(28mm), 2.02(36mm)).

Conclusion: Both cobalt and chromium ion measurements were significantly elevated in the blood and urine of the patients randomized to receive the metal-on-metal bearings at all time intervals. There were no differences seen between the 28mm and 36mm metal-on-metal bearings, keeping all other variables identical. The larger diameter bearing therefore provides the potential clinical advantages of improved range of motion and stability, while providing a similar metal ion profile. While reduced wear is seen with larger diameter metal-on-metal bearings in-vitro, we could not demonstrate a reduction in blood or urine metal ion levels in-vivo.

Kristoff Corten Ward Bartels Guy Molenaers Jos Vander Sloten Paul Broos Johan Bellemans Jean-Pierre Simon

Purpose: Precise biomechanical reconstruction of the hip joint by a hip arthroplasty is essential for the success of this procedure. With the increasing use of surface replacement arthroplasty (SRA), there is a need for better understanding of the key factors that influence the anatomical and the biomechanical parameters of the resurfaced hip joint. The goal of this study was to examine the influence of SRA on the vertical and horizontal offset of the hip.

Method: Twenty-one hips from 12 embalmed cadavers were resurfaced with a Birmingham Hip resurfacing. The thickness of the acetabular bone was measured pre- and post-reaming in 6 acetabular zones. Radiographs were taken before and after the procedure with a scaling marker. For statistical analysis, the paired Student’s T-test with a confidence interval of 95% and a significant p-value of p< 0.05 was used.

Results: The mean acetabular bone loss was 3.8 mm, 5.9 mm, 9.3 mm, 10.6 mm, 8.5 mm and 3.6 mm in zones 1 to 6. The “polar length loss” is the cumulative displacement of the femoral and the acetabular articulating surface in zones 2 to 5. This displacement indicates a shortening of the neck plus a medio-cranial displacement of the acetabular articulating surface and was 4.3 mm, 7.5 mm, 9.4 mm and 7.7 mm (zone 2–5). The radiographic center of rotation (COR) was significantly medialised (mean 6.2 mm) and displaced in the cranial direction (mean 6.9 mm) (p< 0.00001). The mean total (femoral plus acetabular) horizontal and vertical offset change was 6.4 mm and 9.5 mm respectively (p< 0.00001). There was a significantly higher vertical offset change in the acetabulum than in the femur (p=0.0006). This resulted in a significantly larger change in vertical than in horizontal offset (p=0,04).

Conclusion: The displacement of the acetabular COR was responsible for 60% of the total vertical and 99% of the total horizontal offset change. The femoral side did not compensate for this displacement. SRA did not restore the biomechanics of the native hip.

Rajeshkumar Kakwani Chris Wainwright Gautam Tawari Shankar Kashyap A. Roysam A. Nanu

Purpose: A single blind prospective randomised controlled trial comparing the Metal-on-polyethylene articulation with the metal-on-metal articulation in THA.

Method: The clinical and radiological findings of the consecutive patients who were enrolled in the RCT at the participating centres were recorded prospectively. The clinical evaluation was performed with the Harris scoring system as well as the Oxford Hip Scoring Sheet. The computer randomised option was revealed to the operative surgeon only after the patient was anaesthetised, during the recruitment period (June 1998 to July 2004). Of the total of 378 patients, 2 died prior to the final review and 63 were lost to follow-up. The final study group contained 315 patients, with 159 patients in the metal-on-polyethylene group and 156 patients in the metal-on-metal group.

Results: The indication for the hip arthroplasty for majority (309 patients) was primary osteoarthritis. The average age at the time of the surgery was 68.2 years and the average duration of follow-up was 85 months (42–115). There was an improvement of the Oxford hip scores from an average of 37 per-operatively to 16 postoperatively. The Harris hip scores also improved from an average of 47.0 pre-operatively to 87.3 post-operatively. The patient groups were statistically similar with respect to age, sex and duration of follow-up, and the final outcome scores revealed no statistical difference between the two groups.

Conclusion: The clinical results obtained with the use of the articulation are comparable to those obtained by the metal-on-polyethylene articulation encouraging the use of this alternative bearing surface.

Kristoff Corten Filip Van Rykel An Sermon Paul Vanderschot Stefaan Nijs Johan Bellemans Peter Reynders Jean-Pierre Simon Paul Broos

Purpose: Plate and cable alone constructs to treat periprosthetic fractures around a well-fixed femoral stem in total hip replacements, have been reported with high failure rates. The aim of this study was to evaluate the results of our surgical treatment algorithm to reliably use lateral plate and cable constructs in these fractures.

Method: One hundred and six periprosthetic fractures in 102 patients were treated between 1996 and 2006. Forty-five fractures were pre-operatively assessed as Vancouver type B1 fractures. The joint was always dislocated and stability of the implant was meticulously evaluated. This led to the identification of nine (20%) unstable stems leaving 36 fractures to be real B1-type fractures. The fracture was considered to be suitable for lateral plate and cable alone fixation if the medial cortex was not comminuted and an anatomical reduction of the medial cortex could be achieved. Twenty-nine B1- and 5 C-type fractures had been treated with a single lateral plate and cable construct. The mean length of follow-up was 43.2 months. The paired Student’s T-test with a confidence interval of 95% and a significant p-value of p< 0.05 was used to compare the pre- and postoperative UCLA hip scores.

Results: Four (12%) patients died within one month from surgery leaving 30 patients for follow-up. Twenty-nine fractures united at a mean of 6.4 months. One B1-type construct failed due to inappropriate proximal fixation. Two fractures united uneventfully with a mean of 8° of varus alignment of the proximal fragment. One patient with a C-type fracture sustained a fracture distal to the tip of the plate. There were three plate infections (8.8%). There was no significant difference between the pre- and post-operative UCLA hip scores (25 versus 23 resp.).

Conclusion: These fractures represent a difficult problem with a high complication rate of 30%. The presented treatment algorithm contributed significantly to the 97% union rate with plate and cable alone constructs that was comparable to the union rates achieved with combined plate and strut graft fixation.

Mohammad T. Ghazavi Zahra Farahani Mansour Abolghasemian

Purpose: Total hip arthroplasty in high riding congenital dislocation of the hip is a challenging procedure. In order to position the cup in the true acetabulum, femoral shortening osteotomy is often needed. The purpose of our study was to evaluate the results of two different methods of femoral shortening osteotomy.

Method: Thirty-one total hip arthroplasties were performed in 29 cases with high congenital hip dislocation. The acetabular cups were placed at true acetabulum and femoral shortening osteotomies of the femur were performed at proximal (14 hips, group 1) or distal femur (17 hips, group 2). After a mean follow up of 4.2 years, all 31 hips were evaluated with Harris Hip Scores and X-rays. Technical difficulties and complications were also reported.

Results: The mean increase in Harris Hip Score was 51 in group one and 52 in group two. There was one peroneal nerve palsy and one early dislocation in group 1, while there was no such perioperative complications in group 2. One acetabular cup and femoral stem were revised in group 1. Non-union happened in two cases of group 2. Special shape (cylindrical, non-tapered and longer than standard) femoral stems were needed for most proximal osteotomy patients.

Conclusion: Hip arthroplasty, with insertion of cup at true acetabulum and femoral shortening osteotomy in patients with high congenital dislocation, can produce good results. Either proximal or distal femoral shortening osteotomy could have advantages and disadvantages. Proximal shortening osteotomy is a more challenging procedure, may need special stem design, and could compromise stem fixation.

Stephen M. Blake Graham A. Gie Dan Williams Matthew Hubble Andrew J. Timperley

Purpose: Removal of all foreign material is the normal practice at the time of revision arthroplasty for sepsis. However, removal of well-fixed bone cement is time consuming, can result in significant bone stock loss and increases the risk of femoral shaft perforation or fracture. We have performed two-stage revision for infection in a series of cases in which we have left oseeointegrated femoral cement at the first stage and we present the results of this technique.

Method: All patients underwent two-stage revision for infection. At the first stage the prostheses and acetabu-lar cement were removed but when the femoral cement mantle demonstrated good osseo-integration it was left in-situ. Following Girdlestone excision arthroplasty (GEA), patients received local antibiotics delivered by cement spacers, as well as systemic antibiotics. At the second stage the existing cement mantle was reamed, washed and dried and then a femoral component was cemented into the old mantle.

Results: Sixteen patients (M:F 5:11) had at least three years follow up (mean 80 months, range 43 to 91). One patient died of an unrelated cause at 53 months. Recurrence of infection was not suspected in this case. The mean time to first stage revision was 57 months (3 to 155). The mean time between first and second stages was 9 months (1 to 35). Organisms were identified in 14 (87.5%) cases (5 Staphylococcus Aureas, 4 Group B Streptococcus, 2 Coagulase negative Staphylococcus, 2 Enterococcus Faecalis, 1 Escheria Coli). At second stage, five (31.2%) acetabuli were uncemented and 11 (68.8%) were cemented. There were two complications; one patient dislocated 41 days post-operatively and a second patient required an acetabular revision at 44 days for sudden loss of fixation. No evidence of infection was found at re-revision. One patient has been revised for recurrent infection. Currently no patients are suspected of having a recurrence of infection.

Conclusion: Retention of a well-fixed femoral cement mantle during two-stage revision for infection and subsequent in-cement reconstruction is safe with a cure rate of 93%. Advantages include a shorter operating time, reduced loss of bone stock, improved component fixation and a technically easier second stage procedure.

Rajiv Gandhi Fahad Razak J Roderick Davey Khalid Syed Rubini Pathy Nizar N. Mahomed

Purpose: Prophylactic use of antibiotic-laden bone cement (ALBC) has been proposed to decrease the incidence of deep infections. We asked if the use of antibiotic laden bone cement decreased the deep infection rate following primary total knee replacement (TKA) as compared to plain bone cement (PBC).

Method: We surveyed 1,625 consecutive patients undergoing cemented, primary knee replacement with either ALBC or PBC. Relevant covariates including age, body mass index (BMI), gender, education, and medical comorbidity were collected. Joint pain and functional status were assessed at baseline and at 1 year follow up with the respective Western Ontario McMaster University Osteoarthritis Index (WOMAC) scores. The incidence of deep infection at 1 year follow up was recorded.

Results: There were 811 (49.9%) patients in the ALBC group and 814(50.1%) in the PBC group. There were no differences in age, gender, BMI, education or comorbidity between groups at baseline (p> 0.05). We found a deep infection rate of 3.1% in the ALBC group and 2.2% in the PBC group (p=0.27). Adjusted analysis showed that ALBC was not predictive of a lower infection rate at 1 year (p=0.84).

Conclusion: ALBC did not reduce the incidence of deep infection following primary TKA at 1 year follow up. Further studies are needed to define any high risk groups for which ALBC might be beneficial.

Rajiv Gandhi Fahad Razak Peggy Tso J Roderick Davey Nizar N. Mahomed

Purpose: Metabolic syndrome (MS) is defined as central adiposity, elevated fasting glucose, hypertension, and dyslipidemia defined as high triglyceride and low high-density lipoprotein (HDL) cholesterol. MS is associated with a systemic proinflammatory and prothrombotic state. We asked if patients with MS undergoing total knee arthroplasty (TKA) have an increased risk for symptomatic deep vein thrombosis at 3 months follow-up (DVT).

Method: 1,460 consecutive patients were reviewed from our joint registry undergoing primary, unilateral TKA between the years of 1998–2006. Demographic variables of age, gender, comorbidity, and education were retrieved. Metabolic syndrome (MS) was defined as body mass index above 30 kg/m2, diabetes, hypertension, and hypercholesterolemia. Logistic regression was used to examine the relationship of MS on the incidence of DVT.

Results: The overall incidence of symptomatic DVT was 4.4% (65/1460). Patients with MS had an increased incidence of DVT as compared to those without MS(15.5% vs 3.4%). Adjusted analysis showed that MS increased the risk of symptomatic DVT by 3.2(95% CI [1.0,15.4], p=0.04) times compared to those without MS.

Conclusion: Hospital protocols developed for prophylactic anti-coagulation following TKR should give special consideration to patients with MS.

Elie Ghanem Ian Pawasarat Camil Restrepo Khalid Azzam Lauren May Matthew S. Austin Javad Parvizi

Purpose: The purpose of our study is to compare hips to knees in regards to the cost per increase in function, to determine the relationship of economic investment to improved quality of life.

Method: During the year 2005, a total of 23 TKA and 41 THA revisions were performed for aseptic mechanical failure. Patients were enrolled prospectively and quality of life questionnaires including the SF-36, WOMAC, Harris Hip Score (HHS), and Knee Society Score (KSS) were collected prior to and following their procedure at two year follow-up. The total cost of the procedure including the hospital, implant, and surgeon fee were implemented in a cost effectiveness model to calculate the mean cost per SF-36, WOMAC, and HHS or KSS point gained. Demographical variables and co-morbidities were collected to determine risk factors for low cost-effectiveness.

Results: The majority of patients had significant improvement in SF-36, WOMAC, HHS and KSS scales. Patients with THA revisions experience a cost per point increase for HHS of $3,000, and $500 per point SF-36 compared to knee patients who experienced a cost per point increase for KSS of $2,000, and $2,800 per point SF-36. The WOMAC exhibited similar cost effectiveness in the subscales of pain, stiffness and functioning.

Conclusion: There are few studies that have compared the cost effectiveness of total joint arthroplasty revision procedures. Given the increasing cost of health care expenditures, prioritization of funding for the different health practices will become necessary. This study demonstrates that revision THA and TKA are relatively cost effective procedures compared to other non-orthopaedic interventions.

David Backstein Dror Lakstein Oleg Safir Yona Kosashvili Allan E. Gross

Purpose: Acetabular component revision in the context of large, contained bone defects with less than 50% host-bone-contact traditionally required roof reinforcement or antiprotrusio cages. Trabecular Metal (TM) cups (Zimmer, Warsaw, Indiana) may offer a viable treatment alternative. The objective of this study was to evaluate the clinical and radiological outcome of this mode of treatment.

Method: Fifty-four hip revision acetabular arthroplasty procedures performed with TM cups for contained defects offering ≤50% contact with native bone were prospectively followed. Average follow-up was 45 months (range 24–71). All patients were clinically and radiographically evaluated for evidence of loosening or failure.

Results: Contact with bleeding host bone ranged from 0 to 50% (average 23%). At latest follow up 43 (79.6%) arthroplasties had excellent or good results, 8 (14.8%) cases had medium or fair results and 3 cases (5.6%) had poor results. Two cups failed and had to be revised. Two additional cups had radiological evidence of probable loosening. Overall preliminary survivorship of the revision acetabulae was 96%. Complications included 4 dislocations and 1 sciatic nerve palsy.

Conclusion: Treatment of cavitary defects with less than 50% host-bone contact with using TM cups, without structural support by augments or structural bone grafts, is a viable option.

R. Stephen J. Burnett Ajay Aggarwal Stephanie A. Givens J. Thomas McClure Robert L. Barrack

Purpose: Prophylactic antibiotics are frequently withheld until cultures are obtained in revision TKA. A prospective study was undertaken to determine whether prophylactic pre-operative IV antibiotics would affect the results of cultures obtained intra-operatively.

Method: A consecutive series of 25 TKA’s with a known infecting organism were enrolled over 36 months. Inclusion criteria: clinically infected TKA, a known preoperative infecting organism, and no recent antibiotic therapy. Re-aspiration of the infected TKA was performed following anesthesia and sterile prep. IV antibiotic prophylaxis was then administered and the tourniquet was then inflated. Intra-operative culture swabs and tissue were obtained at arthrotomy. The timing of events was recorded. Pre/post antibiotic culture data were analyzed to determine the effect of IV preoperative prophylactic antibiotics on cultures obtained intra-operatively.

Results: Mean time from end of antibiotic infusion to tourniquet inflation was 15 minutes; to arthrotomy culture was 25 minutes. In all 25 knees the organism(s) cultured at arthrotomy were the same as obtained at pre-operative aspiration. In 24 knees the organism cultured was sensitive to the preoperative prophylactic antibiotics given (Ancef and Vancomycin); one patient grew Candida albicans.

Conclusion: Pre-operative prophylactic antibiotics did not affect the results of intra-operative cultures, and should not be withheld prior to infected TKA surgery when an organism has been identified on aspiration. Based on these results, holding pre-operative antibiotics prior to revision TKA is rarely justified.

David Backstein Yona Kosashvili Oleg Safir Dror Lakstein Matthew MacDonald Allan E. Gross

Purpose: Pelvic discontinuity associated with bone loss is a complex challenge in acetabular revision surgery. Reconstruction with anti protrusion cages, Trabecular Metal (Zimmer, Warsaw, Indiana) cups and morselized bone (Cup-Cage) constructs is a relatively new technique used by the authors for the past 6 years. The purpose of the study was to examine the clinical outcome of these patients.

Method: Thirty-two consecutive acetabular revision reconstructions in 30 patients with pelvic discontinuity and bone loss treated by cup cage technique between January 2003 and September 2007 were reviewed. Average clinical and radiological follow up was 38.5 ± 19 months (range 12 – 68, median 34.5). Failure was defined as component migration > 5mm.

Results: In 29 (90.6%) patients there was no clinical or radiographic evidence indicative of loosening at latest follow up. Harris Hip Scores improved significantly (p< 0.001) from 46.6 ± 10.4 to 78.7 ± 10.4 at 2 year follow up. In 3 patients the construct migrated at 1 year post surgery. One construct was revised to anti protrusion cage with a structural graft while the other was revised to a large Trabecular Metal cup. The third patient is scheduled for revision. Complications included 2 dislocations, 1 infection and 1 partial peroneal nerve palsy. Two patients died due to unrelated reasons at 1 and 3 years post surgery, respectively.

Conclusion: Treatment of pelvic discontinuity by Cup-Cage construct is a reliable option based on preliminary results which suggest restoration of the pelvic mechanical stability. However, patients should be followed closely in order to detect cup migration until satisfactory bony ingrowth into the cup takes place.

William D. Fisher Michael Gent Bruce L. Davidson Michael R. Lassen Louis M. Kwong Fred D. Cushner Paul A. Lotke Frank Misselwitz Tiemo J. Bandel Alexander G.G. Turpie

Purpose: Venous thromboembolism (VTE) after major orthopaedic surgery remains an important clinical problem. Convenient, oral antithrombotic agents that are both effective and safe could improve adherence to guidelines for VTE prophylaxis. Recently, the focus has been on the development of oral agents that target a single step in the coagulation cascade and Factor Xa is a pivotal step. Rivaroxaban is an oral, direct Factor Xa inhibitor. Four international phase III trials (the RECORD programme) were undertaken to investigate the safety and efficacy of once-daily rivaroxaban for thromboprophylaxis after major orthopaedic surgery. The results of RECORD3 showed that rivaroxaban was more effective than enoxaparin 40 mg once daily after total knee replacement (TKR), with a 48% risk reduction in VTE and all cause mortality. RECORD4 was designed to determine the efficacy and safety of 10 mg rivaroxaban od compared to 30 mg bid enoxaparin after total knee replacement (TKR).

Method: This study randomized 3148 patients to either rivaroxaban (10 mg od started 6–8 hours after surgery) or enoxaparin (30 mg bid s.c. started 12–24 hours after surgery) for 10–14 days. The primary efficacy outcome was the composite of asymptomatic deep vein thrombosis (DVT) detected by mandatory, bilateral venography and symptomatic DVT, non-fatal pulmonary embolism (PE), and all-cause mortality up to day 13±4. Secondary outcomes included major VTE (composite of proximal DVT, non-fatal PE, and VTE-related death) and symptomatic VTE. Safety outcomes included on-treatment major and non-major bleeding.

Results: Rivaroxaban provided a 31% relative risk reduction in the incidence of the primary efficacy outcome when compared to enoxaparin (6.9% vs 10.1%, respectively; p=0.012). The corresponding rates for major VTE were 1.2% and 2.0%, respectively (p=0.124) and for symptomatic VTE were 0.7% and 1.2%, respectively (p=0.187). There were no significant differences in bleeding incidence observed between rivaroxaban and enoxaparin (major bleeding: 0.7% vs 0.3%, respectively, p=0.110; clinically relevant non-major bleeding: 2.6% vs 2.0%, respectively, p=0.279).

Conclusion: Rivaroxaban 10 mg od is the first oral thromboprophylactic agent to significantly reduce the incidence of VTE after TKR compared to enoxaparin 30 mg bid, with a similar, low rate of bleeding.

Rita Selby Bijan Borah Heather McDonald Joe Henk Mark Crowther Phil Wells

Purpose: A retrospective database analysis was conducted to

determine the extent to which the American College of Chest Physicians (ACCP) guidelines for VTE prophylaxis are followed after total hip replacement (THR) and total knee replacement (TKR) and

evaluate the incidence of VTE for patients receiving and not receiving prophylaxis according to ACCP guidelines (‘ACCP’ and ‘non-ACCP’, respectively).

Method: A claims database associated with a large US health plan was linked to the Premier database, which provides details of in-patient medication use. Patients ≥18 years undergoing TKR/THR and enrolled in the health plan 90 days before and 90 days following discharge from hospitalization (or until death) were included. Patients were considered to have received ACCP-guideline prophylaxis if they:

received LMWH, fondaparinux, or VKA following surgery

initiated prophylaxis within one day of surgery (for THR patients) and

were prescribed prophylaxis for a minimum of ten days, or until the occurrence of major bleeding, VTE, or death. In addition, the number of DVTs and PEs occurring in ACCP and non-ACCP patients was recorded.

Results: Of the 30,644 eligible patients from the health plan, 3,497 patients were linked to the in-patient database. Except for geographic indicators, there were no significant differences in demographics or baseline co-morbidities between those included and excluded from the final study sample. Of the 3,497 linked patients, 1,395 (40%) received ACCP prophylaxis. The number of DVTs occurring in the ACCP and non-ACCP groups were 28 (2.01%) and 79 (3.76%), suggesting that non-ACCP patients were almost twice as likely as ACCP patients to have a DVT (p=0.0521). The number of PEs occurring in the ACCP and non-ACCP groups were 2 (0.14%) and 25 (1.19%), respectively, suggesting that non-ACCP patients were 8.5 times more likely than ACCP patients to experience a PE (p< 0.0001).

Conclusion: This study offers a unique perspective on ‘real-world’ prophylaxis patterns and clinical outcomes in THR/TKR patients. It suggests that 40% of patients received ACCP prophylaxis and that patients not receiving ACCP prophylaxis were almost twice as likely to have a DVT and more than eight times as likely to experience a PE.

Martin Bedard Kelly G. Vince John Redfern

Purpose: Stiffness following TKA is devastating and poorly understood. This study was conducted to determine if rotational positioning of tibial and/or femoral components was related to the development of stiffness following TKA. In addition, post-revision rotational alignment was studied to determine if it contributed to improvement.

Method: Patients who presented with stiffness and either a fixed flexion contracture > 15 and/or flexion < 105 degrees were included in the study. 34 revisions were investigated preoperatively by computerized tomography (CT) for rotational evaluation of the components. Clinical and radiographic data were also recorded.

Results: All 34 revisions had some degree of combined internal rotation on the preoperative CT-scan. The net combined angle averaged fourteen point eight degrees of pathologic internal rotation (in excess of the normal eighteen degrees)[1]. The most significant source of internal rotation was the tibial component, with 33 of the 34 patients having internal rotation with a mean pathological (in excess of the normal eighteen degrees) angle of 13.3 degrees (one to 35 degrees). Postoperatively, the combined rotation angle was restored to an average of five point one degrees of external rotation for the eighteen patients with available CT-scans (p < 0.0001). The 34 revised knees were clinically followed for an average of 22 months. The mean preoperative Knee Society knee and function scores were respectively 41.6 and 47.9. The mean preoperative range of motion was 61.4 degrees. Postoperatively, the knee and function scores increased respectively to 77.3 and to 65.7 (p < 0.0045). The mean postoperative range of motion averaged 98.1 degrees (p < 0.0001).

Conclusion: Rotational positioning of the components should be investigated with CT-scan in stiff knees following TKA. Revision surgery of all the components with restoration of an adequate rotational alignment has been shown to improve range of motion, function and pain.

Fiona Ralley James J. Howard Donna Berta Valerie Binns Douglas Naudie

Purpose: Multiple studies have demonstrated the efficacy of Tranexamic Acid (TA) in reducing blood loss and red blood cell transfusion in patients undergoing primary total hip (THA) or knee (TKA) arthroplasty. However, the dosing schedules of either an initial bolus followed by a 6–12 hour infusion or multiple intravenous bolus doses are not ‘user-friendly’ for regular application. The purpose of this study was to assess the efficacy and acceptance of a single dose protocol for the use of TA in primary THA or TKA.

Method: We selected a single dosing schedule of 20mg/kg TA given either prior to skin incision for THA or approximately ten minutes prior to tourniquet release for TKA. The hospital pharmacy supplied the TA rounded off to the nearest 5kg/100mg in a 100ml mini-bag. In March 2008, we introduced the routine use of TA to all patients undergoing primary THA or TKA at our institution. Mini-bags were pre-ordered at the time of the preoperative clinic visit and delivered to the pre-surgical preparation area on day of surgery. One month after implementation of this protocol we compared blood loss, transfusion rates, and hemoglobin at discharge between the patients operated on from April 1 to June 30, 2007 (when this protocol was not in place) to those from April 1 to June 30, 2008. No other routine patient care practices were altered during this time period.

Results: We found a significant reduction in the decrease in hemoglobin from 2007 compared to 2008 for both THA and TKA (46g/L to 39g/L, and 45g/L to 36g/L, respectively), which led to both a reduction in transfusion rates (13.5% to 3.6%, and 13.1% to 2.0%, respectively) and higher hemoglobin levels at discharge. All patients received the TA as ordered.

Conclusion: Dosing and timing of TA is critical to maximize its antifibrinolytic effect. Our weight increment dose protocol led to minimal dose variability, facilitated pharmacy drug preparation, and minimized wastage. This simple ‘user-friendly’ protocol was found to reduce the decrease in hemoglobin and transfusion rates, demonstrating similar efficacy to other more complex dosing schedules. This protocol was well received and accepted by surgeons, anesthesiologists, pharmacy, and nursing staff.

Aaron Bigham James J. Howard Sugantha Ganapathy

Purpose: Spinal epimorph is commonly used as part of multimodal analgesia for patients undergoing total joint arthroplasty. Patients who receive spinal epimorph are at risk for certain post- operative complications. The purpose of this study was to determine the incidence of complications in patients undergoing total joint arthroplasty with administration of spinal epimorph compared to patients undergoing the same procedure who did not receive spinal epimorph as part of their analgesia.

Method: A retrospective chart review of 72 patients in which two age, sex and procedure matched groups were compared for differences in known spinal epimorph complications. One group received spinal epimorph as part of their analgesia while the comparative group did not receive spinal epimorph but rather continuous infusion of local analgesia. Data extraction involved foley and oxygen usage, documented nausea/vomiting and puritis, associated risk factors and complications such as prostate disease and urinary tract infections, and secondary outcome measures such as Gravol and Benadryl usage.

Results: Comparison of the two well-matched groups demonstrated that patients who received spinal epimorph had increased rates of foley insertion (p=0.0026), foley duration (p=0.015), oxygen usage (p=0.0053), documented puritis (p=0.0006) and Benadryl usage (p=0.0053). Trends towards increased nausea/vomiting (p=0.17), antiemetic use (p=0.16) and urinary tract infections (p=0.15) were seen in the spinal epimorph group, although these differences did not reach statistical significance.

Conclusion: The use of spinal epimorph as part of an analgesia protocol surrounding total joint arthroplasty is associated with increased complications and patient discomfort when compared to patients who received continuous local infiltrative analgesia. Further research is needed to determine if alternate modes of analgesia provide adequate pain relief when compared with spinal epimorph and thus provide suitable alternatives with less complications.

Martyn Snow Jay B. Adlington William D. Stanish

Purpose: To report the 2–5 year results of ACL reconstruction with doubled Tibialis anterior allograft.

Method: Seventy-three patients who underwent primary ACL reconstruction with doubled tibialis anterior allografts with minimum 2 year follow-up were included in the study. Patients were assessed via telephone interview using the Lysholm knee score, Tegner activity score, and the subjective International Knee Documentation Committee rating. In addition, they were asked if they had failure of the ACL requiring revision or any other procedures such as repeat arthroscopy for meniscal surgery/articular cartilage. Statistical analysis using levene’s test and the T-test was used to assess outcomes of patients according to age and sex.

Results: Sixty-four (88%) patients were available for follow-up. The mean age was 28.94 years (16–55). There were 33 males (51.6%) and 31 females (48.4%). The mean follow-up was 41.6 months (range 24–55 months). There were 2 (3%) complications, 1 patient suffered a DVT with subsequent PE, and 1 patient suffered a hardware problem. Four patients (6.3%) had failure of their graft and 6 patients (9%) required repeat arthroscopy. The mean Lysholm score was 91.75 (SD+/− 8.2), and the mean Tegner activity score was 5.4 (range 1–10). The mean IDKC was 88.94 (SD+/− 8.33). According to the IDKC score 58% of patients were rated as excellent, 27% as good, and 13% as fair and 2% as poor. There was no difference in outcome in patients under 30 compared to over 30 years. Males performed statistically better on the Lysholm and the IKDC scores (p 0.005 and 0.038 respectively) when compared to women.

Conclusion: ACL reconstruction with Allograft Tibialis anterior tendon provided good functional results with a low failure rate at 2–5 years. There was no statistical difference in outcome between Patients under 30 years and those above 30 years. Males performed better on the Lysholm and the IDKC questionnaires.

Randy Mascarenhas Michael Tranovich John Karpie James Irrgang Freddie H. Fu Christopher D. Harner

Purpose: This study sought to compare clinical outcomes and return to activity in high-demand patients following ACL reconstruction with either autograft or allograft patellar tendon using a matched-pairs case-control experimental design.

Method: Nineteen matched pairs were obtained based on gender (36.8 % female), age (27.9±8.1yrs autograft versus 28.1±9.1 allograft), and length of follow-up (9.1±2.7yrs autograft versus 10.3±2.6 allograft). All patients reported participating in very strenuous (soccer, basketball etc.) or strenuous (skiing, tennis etc.) sporting activity 4–7 times/ week prior to their knee injury. Patient-reported outcomes included the IKDC Subjective Knee Form, Activities of Daily Living (ADLS) and Sports Activity Scales (SAS) of the Knee Outcome Survey and SF-36. Range of motion, laxity, and functional strength were also assessed.

Results: There were no significant differences in patient-reported or clinical outcome measures. Sixteen (84.2%) subjects undergoing autograft reconstruction and 12 (63.2%) subjects reconstructed with allograft were able to participate in strenuous or very strenuous sporting activity at follow-up (p=.34). Similar percentages of subjects were able to return to their pre-injury level of sports activity [12 (63.2%) autograft vs. 11 (57.9%) allograft; p=1.0]. Fewer subjects undergoing reconstruction with autograft reported instability with very strenuous activity [5 (26.3%) autograft vs. 12 (63.2%) allograft], but this difference was not significant (p=.07).

Conclusion: While autograft and allograft patellar tendon ACL reconstruction exhibit similar clinical outcomes in high-demand individuals, autogenous patellar tendon grafts may be indicated to allow patients to return to very strenuous levels of activity.

Michael G. Zywiel Peter M. Bonutti Slif D. Ulrich Mike S. McGrath Michael A. Mont