The treatment of bony defects of the tibia at the time of revision total knee replacement is controversial. The place of compacted morsellised bone graft is becoming established, particularly in contained defects. It has previously been shown that the initial stability of impaction-grafted trays in the contained defects is equivalent to that of an uncemented primary knee replacement. However, there is little biomechanical evidence on which to base a decision in the treatment of uncontained defects. We undertook a laboratory-based biomechanical study comparing three methods of graft containment in segmental medial tibial defects and compared them with the use of a modular metal augment to bypass the defect. Using resin models of the proximal tibia with medial defects representing either 46% or 65% of the medial cortical rim, repair of the defect was accomplished using mesh, cement or a novel bag technique, after which impaction bone grafting was used to fill the contained defects and a tibial component was cemented in place. As a control, a cemented tibial component with modular metal augments was used in identical defects. All specimens were submitted to cyclical mechanical loading, during which cyclical and permanent tray displacement were determined. The results showed satisfactory stability with all the techniques except the bone bag method. Using metal augments gave the highest initial stability, but obviously lacked any potential for bone restoration.
When using a staged approach to eradicate chronic infection after total hip replacement, systemic delivery of antibiotics after the first stage is often employed for an extended period of typically six weeks together with the use of an in situ antibiotic-eluting polymethylmethacrylate interval spacer. We report our multi-surgeon experience of 43 consecutive patients (44 hips) who received systemic vancomycin for two weeks in combination with a vancomycin- and gentamicin-eluting spacer system in the course of a two-stage revision procedure for deep infection with a median follow-up of 49 months (25 to 83). The antibiotic-eluting articulating spacers fractured in six hips (13.9%) and dislocated in five patients (11.6%). Successful elimination of the infecting organisms occurred in 38 (92.7%) of 41 hips with three patients developing superinfection with a new organism. We conclude that prolonged systemic antibiotic therapy may not be essential in the two-stage treatment of a total hip replacement for Gram-positive infection, provided that a high concentration of antibiotics is delivered locally using an antibiotic-eluting system.
Anterior Lumbar Interbody Cages are used to recreate the lumbar lordosis in scoliosis surgery as anterior instrumentation is usually kyphogenic. We report two cases in which an anterior release was performed and interbody cages were used.In both these patients the cage was displaced anteriorly by an incorrectly positioned pedicle screw during posterior instrumentaion. In one case the cage was retrieved and correctly repositioned from the back using a TLIF approach, in the other this was noticed only post-operatively and patient needed another anterior surgery. We recommend a lateral Image Intensifier screening for combined anterior and posterior cases in which anterior cages are used in addition to posterior pedicle screws to prevent this complication.
Pedicle screw fixation has become the norm for the surgical correction of adolescent idiopathic scoliosis (AIS), with much biomechanical research into different types of rod screw constructs. The senior authors have experience using a monoaxial screw only construct in the correction of AIS since 2003 and the polyaxial screw only construct since 2005. We retrospectively reviewed our experience in the first ten patients with AIS using the polyaxial system and compared this against 18 patients who had been corrected using the monoaxial system. Table I shows our results, expressed as mean and ranges or means ± SD for the main thoracic and lumbar curves. Our early results show that the polyaxial system produces similar correction of both the thoracic and lumbar curves as compared to the monoaxial system in the immediate post-operative period. Though the absolute values for the lumbar curves differ between the two groups the percentage correction shows no statistical difference.
Work supported by Fondation Cotrel
Routine inclusion of imaging of the SI joint as part of lumbosacral spine MRI for back pain and sciatica shows only 3% positive results. SI joint should be imaged only if clinically suspected.
Paravertebral anaesthesia is a particularly effective, safe and reliable option in scoliosis patients undergoing anterior release in whom percutaneous epidural placement may be difficult to perform. A recent systematic review and meta-analysis of randomized trials has demonstrated that whilst paravertebral block and thoracic epidural insertion provide comparable pain relief after thoracic surgery, paravertebral block placement is associated with a better side effect profile, including a reduction in pulmonary complications, hypotension, nausea and vomiting and urinary retention. We describe a case of a 16 year old female patient who underwent staged correction of her thoracolumbar scoliosis. A paravertebral catheter was inserted under direct vision for continuous infusion post operative analgesia following the anterior release. 48 hours after surgery a swelling was noted in the groin, which was confirmed with ultrasonography as a fluid collection. The swelling resolved upon removing the paravertebral catheter. This suggests that it was caused by the local anaesthetic fluid tracking along the psoas muscle. Retroperitoneal infections, venous thrombosis, femoral hernia, femoral artery aneurysm and inguinal lymphadenopathy are other differentials. Ultrasonography was a fast and sensitive investigation to rule out these differentials and determined that fluid communicating with the abdominal cavity was the cause for this swelling. The infused local anaesthetic had tracked down into the femoral triangle and the swelling resolved upon cessation of the infusion.
to measure the total metal content in cell saver blood recovered during revision hip arthroplasty, to evaluate the efficacy of centrifuging and washing the recovered blood in reducing the metal content, to investigate whether transfusion of the salvaged blood resulted in a significant increase in the metal ion levels in the patients’ blood in the immediate post-operative period.
Average age was 6.5 years(2–12). Average follow-up was 24 months (6m-36m).
We studied the long term outcome, using the Oswestry Disability Index (ODI), on patients who were managed at our institution between February, 1997, and August, 2004, with a diagnosis of a primary spinal infection, excluding TB or post-operative infection. Patients were identified from databases held within the Departments of Radiology, Orthopaedic Surgery, Neurosurgery and Microbiology. This identified 98 adult patients who fulfilled our inclusion criteria, of who ODIs were calculated on 66, with a mean follow-up of 5 years. There were initially 53 male and 45 female patients with a mean age of 60 years (range 21 0 86) at presentation and symptoms had been present on average for 72 days prior to admission. Back pain was the predominant symptom in 59 and neuropathy in 43. Our figures would suggest a mush higher incidence of primary spinal infection than previously quoted. 75% had significant co-morbidities and 85% of patients under 40 years of age were IV drug users. The causative organisms and their effect were noted. Admission WCC (mean 11.5 ± 8.6) and CRP (mean 128 ± 48) were obtained in the majority of patients (97/98 &
94/98). For those patients who were still available to f/u, the mean ODI was 32 ± 25.
It might be a useful predictor in most of the spine surgery. We have incorporated pain diagrams in the questionnaires of patients undergoing anterior spinal surgery and dynamic stabilisation of spine.
The aims of this study were
to develop the Roche lightcycler Staphylococcal and Enterococcal PCR kits to facilitate diagnosis of hip and knee prosthetic infections To analyse results together with bacteriological and histological findings.
29 patients had non-inflammatory arthritis. 14/18 (77.8%) with positive cultures had staphylococci +/or enterococci isolated and 10 PCR results correlated. The other 11 patients had negative cultures. 9 patients had inflammatory arthritis. Six were culture negative and of the other three, 2 were positive for staphylococci on culture with 1 positive by PCR.
Enterococcal PCR confirmed culture positivity in 2/3 patients. An additional 5 positive PCR’s were obtained from patients’ culture negative for enterococci. It is not clear if these are false positives or more sensitive detection of enterococcal isolation.
Five specimens were implanted for each group 1) with pedicle screw (into L3 and L5) and tested with/without Synex (expandable) cage anteriorly, 2) implanted with a Synex cage and Double screw+rod Ventrofix system, 3) Synex cage and Double screw+ Single rod Ventrofix construct and 4) Synex cage and Single screw+ Single rod Ventrofix system.
The double screw/ single rod system is less effective than the Ventrofix System but is comparable to the pedicle screw construct. The single screw/ single rod construct leads to unacceptable movement about the axis of the inferior screw particularly in extension with a ROM much greater than the intact spine (p<
0.001)
Pre and post procedure pain and physical function scores were noted using the standard SF 36 questionnaire, as well as whether subsequent surgery was required. Mean follow up time was seven months (range 2–13 months).
Physical activity is a key determinant of bone mass and health, however during adulthood and ageing there appears to be a decrease in the ability to respond positively to exercise which is variable between individuals. While exercise is known to protect against the osteopo-rotic process with modest increases in BMD the exact cellular and molecular responses are poorly understood. We have studied the effect of mechanical stimulation on bone histomorphometric parameters, osteocyte viability and gene expression in human trabecular bone maintained in a 3D bioreactor. Trabecular bone cores were prepared from femoral head tissue removed from patients undergoing total hip arthroplasty and maintained in the bioreactor system for 3 (n= 4 patients), 7 (n=5 patients) or 28 days (n=1 patient). Cores (n=3 per patient) were either frozen directly on preparation (T0), placed in the bioreactor system and subjected to Mechanical stimulation (3000 μstrain in jumping exercise waveform repeated at 1Hz for 5 minutes daily) or maintained in the bioreactor system with no mechanical stimulation as control. After the experimental period total cell numbers, cell viability and apoptosis were determined in un-decalcified cryosections at specific distances throughout the bone cores by nuclear staining (DAPI), lactate dehydrogenase activity (LDH) and Nick Translation Assay respectively. Consecutive sections were collected and RNA extracted for gene expression analysis. Mechanical stimulation was shown to increase Bone Formation Rate (BFR) as determined by Calcein label/ distance to bone surface in the 28 day experiment (BFR mcm/day Control 0.01 ± 0.0035 vs Load 0.055 ± 0.0036 p=0.0022). Expression of bone formation markers such as Alkaline Phosphatase and Collagen Type I was shown to increase in all patients however there was an individual variation in the response of Osteopontin to mechanical stimulation as determined by quantitative real time PCR expression analysis. Numbers of viable osteocytes at T0 varied between individual patients however viability was significantly increased and apoptosis decreased in association with mechanical stimulation compared to control in all patient samples examined (p to 0.021). Our data tend to support animal model findings relating to the osteocyte saving effects of exercise and provide an insight into the molecular detail of the exercise response in human bone.
We report 17 patients (20 hips) in whom metal-on-metal resurfacing had been performed and who presented with various symptoms and a soft-tissue mass which we termed a pseudotumour. Each patient underwent plain radiography and in some, CT, MRI and ultrasonography were also performed. In addition, histological examination of available samples was undertaken. All the patients were women and their presentation was variable. The most common symptom was discomfort in the region of the hip. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. To date, 13 of the 20 hips have required revision to a conventional hip replacement. Two are awaiting revision. We estimate that approximately 1% of patients who have a metal-on-metal resurfacing develop a pseudotumour within five years. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris. We are concerned that with time the incidence of these pseudotumours may increase. Further investigation is required to define their cause.
A combination of stem cell therapy and tissue engineering is emerging as one of the most promising approaches for skeletal tissue repair and regeneration. Osteoinduction of human bone marrow mesenchymal stem cells (MSCs) is initiated through local signals or growth factors, of which the bone morphogenetic proteins (BMPs) are the best characterised. Cytomodulin-1 (CM-1), a synthetic heptapeptide with functional similarity to members of the TGF-B super family, has been classified as a novel growth factor associated with osteoinduction of MSCs. However, the effects of CM-1 on human bone MSCs are still unclear. The aim of this study was to determine any effects for CM-1 and its scrambled control (CM-1 SCRAM) on the proliferation and differentiation of human bone marrow MSCs along the osteogenic lineage. Primary human bone marrow MSCs were cultured in the presence of CM-1 and CM-1 SCRAM at a range of concentrations (10-8M – 10-6M) in vitro for up to three weeks. 100 ng/mL of recombinant human BMP-2 (rhBMP-2) was used as a positive control. At the end of the culture period, histological and biochemical assays were carried out on the cultures. Biochemical assays revealed that 10-7M of CM-1 significantly stimulated alkaline phosphatase specific activity compared with the negative control group (P<
0.05) in a similar way to the rhBMP-2 positive control group. These data were supported by an observed increase in positive alkaline phosphatase staining in the 10-7M of CM-1 and rhBMP-2 treated cells. However, total DNA content was not significantly different between any of the groups. This study indicated the potential of using CM-1 as an osteogenic growth factor for skeletal tissue regeneration which may provide an alternative approach to meet the major clinical need in orthopaedics and craniofacial surgery. * Cytomodulin-1 and the scrambled control were genuine gifts from Professor (emeritus) Rajendra S. Bhatnagar at the Department of Bioengineering, University California Berkley, USA.
We report the clinical, radiographic and histologic features of these cases.
There were no infections in this series. Three subjects required revision surgery.
This study suggests that resurfacing arthoplasty can also induce a local hypersensitivity reaction in response to metal wear debris. It therefore raises new concerns regarding the long-term safety of this procedure.
Patella and extensor mechanism injuries are common injuries and are generally managed with some degree of immobilisation and partial weight bearing to facilitate healing. The aim of this project was to determine the type of immobilisation or splintage during partial weight bearing that results in minimal forces acting through the extensor mechanism. Gait analysis studies were performed on eight healthy male subjects mobilising partially weight bearing. Measurements were taken for six types of immobilisation: locked at 0, 10, 20, 30 degrees and unlocked in an orthotic knee brace, and without a brace. The ground reaction force, knee joint angle and the knee flexion moment were measured using Qualisys Track Manager and Visual 3D Software. The extensor mechanism moment and the extensor mechanism force were calculated using static equilibrium equations and documented data. A one-way analysis of variance statistical test was performed to determine the statistical significance of the differences between the six types of immobilisation. There was a direct relationship between the knee flex-ion angle and the extensor mechanism force. The extensor mechanism force at 0 degrees of immobilisation was significantly lower than that for 20 and 30 degrees (p<
0.05). The increase in the extensor mechanism moment arm with increasing knee flexion was not suf-ficient to offset the increase in the extensor mechanism force caused by the increase in the knee flexion moment. The results also showed that the knee flexion angle does not always correspond with the angle set at the knee brace; however they did exhibit a direct relationship. These results have important implications for the management of patients with patella and extensor mechanism injuries. The results suggest that improvements in knee brace design to allow 0 degrees of knee flexion, rather than the 10 degrees as seen in this study, are likely to result in significantly reduced extensor mechanism tensile forces.
There is concern that intra-articular electrosurgical ablation may cause thermal soft tissue damage, particularly chondrolysis, if excessive temperatures are reached. The aim of this study was to determine whether the intra-articular temperature during arthroscopic subacromial decompression using a monopolar electrosurgical ablator remains below a safe level. Data was collected prospectively from consecutive shoulder arthroscopic subacromial decompressions performed at our institution. Shoulder arthroscopy was performed using three standard portals. Evaluation of the glenohumeral joint and subacromial space was performed in a standard manner. Soft tissue resection of the subacromial bursa was performed using a monopolar electrosurgical ablator probe with continuous integral suction. Additional procedures such as acromioclavicular joint excision and rotator cuff debridement or repair were performed as appropriate. Bone resection, if required was performed using an arthroscopic burr. The temperature of the fluid within the shoulder and subacromial space was continuously monitored using a sterile digital temperature probe. The surgeon performing the procedure was blinded the collection of data. Data from thirty subacromial decompressions has been collected. 8 patients had full thickness cuff tears of which 6 were debrided, and 2 repaired arthroscopically. 13 patients had acromioclavicular joint excision. Mean operating time was 46 minutes (30–107). The infusion pressure ranged from 40 to 65 mmHg. The median volume of infused fluid was 3900 ml (1500 to 9000). The starting temperature ranged from 18.3 to 21.9. The mean maximum temperature reached was 27.6 (range 22.7 to 41.8 °C). The results suggest that the intra-articular temperature is maintained within safe levels when a monopolar electrosurgical ablator with integral suction is used to perform soft tissue subacromial decompression.
We have examined the outcome in 19 professional rugby union players who underwent anterior cervical discectomy and fusion between 1998 and 2003. Through a retrospective review of the medical records and telephone interviews of all 19 players, we have attempted to determine the likelihood of improvement, return to professional sport and the long-term consequences. We have also attempted to relate the probability of symptoms in the neck and radicular pain in the arm to the position of play. Neck and radicular pain were improved in 17 patients, with 13 returning to rugby, the majority by six months after operation. Of these, 13 returned to their pre-operative standard of play, one to a lower level and five have not played rugby again. Two of those who returned to the game have subsequently suffered further symptoms in the neck, one of whom was obliged to retire. The majority of the players with problems in the neck were front row forwards. A return to playing rugby union after surgery and fusion of the anterior cervical spine is both likely and safe and need not end a career in the game.
The creep and wear behaviour of highly cross-linked polyethylene and standard polyethylene liners were examined in a prospective, double-blind randomised, controlled trial using radiostereometric analysis. We randomised 54 patients to receive hip replacements with either highly cross-linked polyethylene or standard liners and determined the three-dimensional penetration of the liners over three years. After three years the mean total penetration was 0.35 mm (SD 0.14) for the highly cross-linked polyethylene group and 0.45 mm (SD 0.19) for the standard group. The difference was statistically significant (p = 0.0184). From the pattern of penetration it was possible to discriminate creep from wear. Most (95%) of the creep occurred within six months of implantation and nearly all within the first year. There was no difference in the mean degree of creep between the two types of polyethylene (highly cross-linked polyethylene 0.26 mm, SD 0.17; standard 0.27 mm, SD 0.2; p = 0.83). There was, however, a significant difference (p = 0.012) in the mean wear rate (highly cross-linked polyethylene 0.03 mm/yr, SD 0.06; standard 0.07 mm/yr, SD 0.05). Creep and wear occurred in significantly different directions (p = 0.01); creep was predominantly proximal whereas wear was anterior, proximal and medial. We conclude that penetration in the first six months is creep-dominated, but after one year virtually all penetration is due to wear. Highly cross-linked polyethylene has a 60% lower rate of wear than standard polyethylene and therefore will probably perform better in the long term.
When deciding on treatment for displaced mid-shaft clavicle fractures, patients often inquire if repair of (potential) nonunion results in outcome similar to acute fixation. We used objective muscle strength testing and patient-oriented outcome measures to examine this question. Late reconstruction of nonunion following displaced mid-shaft fractures of the clavicle results in restoration of objective muscle strength similar to that seen with immediate fixation. However, there was a significant loss in muscle endurance as well as a trend towards a decrease in outcome scores (DASH, Constant) following late reconstruction. This information is useful in surgical decision making and in counseling patients. Using objectively measured strength and patient-oriented health-status instruments, we sought to determine if delay in repair of displaced, mid-shaft clavicle fractures negatively affected shoulder strength or outcome. Late reconstruction of clavicle nonunion results in restoration of objective muscle strength similar to that seen with immediate fracture fixation, but there was a significant loss in muscle endurance as well as a trend towards a decrease in outcome scores (DASH, Constant). All patients had sustained completely displaced, closed, isolated mid-shaft clavicle fractures. Fifteen patients had immediate plate fixation (mean 0.6 months post-fracture) and fifteen had plate fixation for non-union (mean fifty-eight months post-fracture). Objective muscle strength testing on the BTE was done a mean of twenty-nine months post-fixation (normal contralateral limb as control). There were no significant differences between acute fixation and delayed reconstruction groups with regards to strength of shoulder flexion (acute = 92.4%, delayed = 89.4%, p=0.56), shoulder abduction (acute = 98.8%, delayed = 96.7, p=0.75), external rotation (acute = 98.4%, delayed = 91.9%, p=0.29), or internal rotation (acute = 96.3%, delayed = 97.4%, p=0.87). However, there was a trend for improved Constant scores (acute = 94.5, delayed = 90, p=0.09) and the DASH scores (acute = 3.4, delayed = 9.0, p=0.09) in the acute fixation group. We found a significant decrease in muscle endurance with regards to shoulder flexion (acute = 107.0%, delayed = 71.1%, p=0.007) and a trend towards weaker shoulder abduction (acute = 103.1%, delayed = 88.7 %). Funding: Mr. Potter was supported by a St. Michael’s Hospital Summer Student Scholarship
This prospective randomized multicenter study compares two methods of bone defect treatment in tibial plateau fractures: a bioresorbable calcium phosphate paste (Alpha-BSM) that hardens at body temperature to give structural support versus Autogenous iliac bone graft (AIBG). One hundred and eighteen patients were enrolled with a 2:1 randomization, Alpha-BSM to AIBG. There was a significant increased rate of non-graft related adverse affects and a higher rate of late articular subsidence (three to nine month period) in the AIBG group. A bioresorbable calcium phosphate material is recommended in preference to the gold standard of AIBG for bone defects in tibial plateau fractures. This prospective randomized multicenter study was undertaken to compare two methods of bone defect treatment: a bioresorbable calcium phosphate paste (Alpha-BSM –DePuy, Warsaw, IN) that hardens at body temperature to give structural support and is gradually resorbed by a cell-mediated bone regenerating mechanism versus Autogenous iliac bone graft (AIBG). One hundred and eighteen adult acute closed tibial plateau fractures, Schatzker grade two to six were enrolled prospectively from thirteen study sites in North America from 1999 to 2002. Randomization occurred at surgery with a FDA recommendation of a 2–1 ratio, Alpha BSM (seventy-eight fractures) to AIBG (forty fractures). Only internal fixation with standard plate and screw constructs was permitted. Follow-up included standard radiographs and functional studies at one year, with a radiologist providing independent radiographic review. The two groups exhibited no significant differences in randomization as to age, sex, race, fracture patterns or fracture healing. There was however, a significant increased rate of non-graft related adverse affects in the AIBG group. There was an unexpected significant finding of a higher rate of late articular subsidence in the three to nine month period in the AIBG group. Recommendations for the use of AIBG for bone defects in tibial plateau fractures should be discouraged in favor of bioresorbable calcium phosphate material with the properties of Alpha BSM. We believe further randomized studies using AIBG as a control group for bone defect support of articular fractures are unjustified. A bioresorbable calcium phosphate material is recommended in preference to the gold standard of AIBG for bone defects in tibial plateau fractures.
To review the outcome of patients with deep infection using a new 2-stage revision technique. A management plan consisting of initial debridement, insertion of antibiotic spacers and 2 weeks of intravenous antibiotics is currently used. No further antibiotics are given systemically. If blood tests are satisfactory at 12 weeks, reimplantation occurs. Patients are encouraged to partially weight-bear and perform a range of motion exercises with their spacers in place. The necessary data has been prospectively collected to identify predictors of success. Thirty four patients have been identified and fully followed up for more than 1 year. 27 patients have over 2 years of follow-up. When looking at all of the patients we have achieved an 82% success rate. For patients whose only previous major surgery was their arthroplasty this rises to 90%. Where multiple surgeries have been undertaken this falls to 73%. All of the peri-operative investigations have been reviewed and whilst they have a good negative predictive value they are not specific enough to alter practice.
This randomized clinical trial compares fixed- and mobile-bearing total knee prostheses in terms of the patients’ clinical outcome parameters (Knee Society Clinical Rating, WOMAC, SF-12), range of motion and performance during gait analysis for level-ground walking. Our results show no significant differences in the clinical outcomes and gait performance of the fixed- and mobile-bearing total knee arthroplasties. The purpose of this study was to compare the clinical outcomes and gait parameters of patients with a fixed-bearing or mobile-bearing total knee arthroplasty (TKA). Fifty-five patients were entered into a prospective, randomized clinical trial comparing fixed- versus mobile-bearing TKAs (Genesis II, Smith &
Nephew, Memphis, TN). From this patient population, fifteen fixed-bearing and fifteen mobile-bearing TKA patients were matched based on age, sex and BMI to undergo gait analysis. Patients performed trials of level-ground walking at a self-selected velocity while three-dimensional kinetic and kinematic data were collected. The fixed-bearing and mobile-bearing TKA patient groups were comparable regarding Knee Society Clinical Rating (181 ± 22 versus 171 ± 28), WOMAC scores (7 ± 5 versus 9 ± 12), SF-12 and range of motion (121° ± 11° versus 125° ± 6°). Patients with fixed- and mobile-bearing TKAs performed similarly in the gait analysis in terms of their velocity, percent weight acceptance in the operated versus the non-operated limb, peak flexion in stance and swing phases, the support moments and extension moments at the ankle, knee and hip. Decreased peak extension in the mid-stance and swing phases was observed in the operative limb versus the non-operative limb for both fixed- and mobile-bearing TKAs (P=0.02 and 0.04). Decreased peak extension was also observed during mid-stance and swing phases in the mobile-bearing TKAs versus the fixed-bearing TKAs (P=0.064 and 0.052). Fixed-bearing and mobile-bearing TKAs perform similarly in terms of their clinical outcome measures and the kinetics and kinematics of level-ground walking. Funding for this project obtained from Smith &
Nephew, Memphis, TN.
Measures of lower limb alignment and knee joint load during walking were evaluated before and six months after medial opening wedge high tibial osteotomy (HTO) in ninety-five patients with knee medial compartment osteoarthritis (OA). Full-length standing radiographs were used to calculate the mechanical axis angle, and a gait analysis was performed to calculate the external adduction moment about the knee. Results indicated significant decreases in mechanical axis angle and peak adduction moment. These findings provide an indication of the early success of HTO in reducing the extent of lower limb malalignment and knee joint load during walking. Medial opening wedge high tibial osteotomy (HTO) is intended to correct lower limb malalignment, resulting in decreased medial knee joint load and improved function. Due to the potential for the amount of alignment correction to change over time after surgery, frequent follow-up evaluations are encouraged. To evaluate the early changes in lower limb alignment and medial knee joint load experienced during walking after medial opening wedge HTO. Ninety-five patients (seventy-nine males, sixteen females; age range = 21–76 years; BMI range = 18.0–38.5) with knee joint OA affecting primarily the medial compartment underwent radiographic and gait analyses pre-surgically and six months following HTO. Full-length standing radiographs were obtained on both occasions and used to measure the static mechanical axis angle. Three-dimensional kinetic and kinematic data were also collected and combined to calculate the external knee joint adduction moment, an indirect measure of knee joint load. Paired t-tests indicated the mechanical axis angle (mean decrease = 8.32 degrees, 95% CI = 7.54,9.10) and peak external knee joint adduction moment (mean decrease = 1.61%BW*ht, 95% CI = 1.25,1.95) significantly decreased post-operatively (p<
0.001). These results indicate less varus angulation and reduced medial knee joint load following HTO. These preliminary findings suggest that medial opening wedge HTO is an effective surgical treatment for improving alignment and reducing knee joint load. Although these early results are promising, future research is required to determine the long-term success of this surgery in the treatment of knee OA. Funding: CIHR, NSERC, Arthrex Inc.
The peak external knee adduction moment during walking gait has been proposed to be a clinically useful measure of dynamic knee joint load in patients with knee osteoarthritis. However, there is limited information about the reliability of this measure, or its ability to detect change. The test-retest reliability and sensitivity to change of peak knee adduction moments were evaluated in thirty patients with varus gonarthrosis. Indices of relative and absolute reliability were excellent (intra-class correlation coefficient = 0.85, standard error of measurement = 0.36 % BW*Ht), and the sensitivity to change following high tibial osteotomy was high (standardized response mean = 1.2). To estimate the test-retest reliability, measurement error and sensitivity to change of the peak knee adduction moment during gait. Thirty patients (44”11 yrs, 1.7”0.09 m, 87”20 kg, twenty males, ten females) with varus gonarthrosis underwent gait analyses on two pre-operative test occasions within one week, and on a third test occasion six months after medial opening wedge high tibial osteotomy. Three-dimensional kinematic and kinetic gait data were collected during self-paced walking and used to calculate the peak knee adduction moment. An intraclass correlation coefficient of 0.85 (95%CI: 0.71, 0.93) indicated excellent relative reliability, and a standard error of measurement of 0.36 %BW*Ht (95%CI: 0.29, 0.49) indicated low measurement error. The peak knee adduction moment after surgery (1.66”0.72 %BW*Ht) was significantly (p<
0.001) lower than before surgery (2.58”0.72 %BW*Ht). A standardized response mean of 1.2 (95%CI: 0.77, 1.6) indicated the size of this change was large. Based on 95% confidence levels, these results suggest the error in an individual’s peak knee adduction moment at one point in time is 0.70 % BW*Ht, the minimal detectable change in an individual’s peak adduction moment is 1.0 %BW*Ht, and it is sensitive to change following treatment. The peak knee adduction moment during gait has appropriate reliability for use in studies evaluating the effect of treatments intended to decrease the load on the knee. When considering measurement error, the knee adduction moment is also appropriate for clinical use in evaluating change in individual patients. Funding: CIHR, Arthrex Inc.
The Charnley Elite femoral component was first introduced in 1992 as a new design variant of the original Charnley femoral component (De Puy, Leeds, UK) with modified neck and stem geometry. The original component had undergone few changes in nearly forty years and has excellent long-term results. Early migration of the new stem design was determined by Roentgen Stereophotogrammetric Analysis (RSA)1. Rapid early migration of a component relative to the bone, measured by RSA, is predictive of subsequent aseptic loosening for a number of femoral stems. As there was rapid early migration and rotation of the Charnley Elite stem, we predicted that the long-term results would be poor. An outcome assessment is indicated as stems of this type are still being implanted. One hundred Charnley Elite stems, implanted in our centre between 1994 and 1997 were included in a prospective, cross-sectional follow-up study. Outcome measures include validated clinical scores (Charnley hip score, Harris hip score and Oxford hip score) and radiological scores (Gruen classification) as well as revision rates over the past 10 years. The clinical follow-up supports the RSA predictions of early failure of the Charnley Elite femoral stem.
Intramedullary tibial nailing was performed in ten paired cadavers and the insertion of a medial-to-lateral proximal oblique locking screw was simulated in each specimen. Anatomical dissection was undertaken to determine the relationship of the common peroneal nerve to the cross-screw. The common peroneal nerve was contacted directly in four tibiae and the cross-screw was a mean of 2.6 mm (1.0 to 10.7) away from the nerve in the remaining 16. Iatrogenic injury to the common peroneal nerve by medial-to-lateral proximal oblique locking screws is therefore a significant risk during tibial nailing.
We describe the influence of the angle of immobilisation during partial weight-bearing on the forces across the extensor mechanism of the knee. Gait analysis was performed on eight healthy male subjects with the right knee in an orthotic brace locked at 0°, 10°, 20° and 30°, with the brace unlocked and also without a brace. The ground reaction force, the angle of the knee and the net external flexion movement about the knee were measured and the extensor mechanism force was calculated. The results showed a direct non-linear relationship between the angle of knee flexion and the extensor mechanism force. When a brace was applied, the lowest forces occurred when the brace was locked at 0°. At 30° the forces approached the failure strength of some fixation devices. We recommend that for potentially unstable injuries of the extensor mechanism, when mobilising with partial weight-bearing, the knee should be flexed at no more than 10°.
In contrast, the release of the inflammatory cytokine TNF-α and the multifunctional growth factor TGF-β-2 occurred at lower doses (0.0005 to 5 μm3/cell for TNF-α and 0.5 to 50 μm3/cell for TGF-β-2). No release of IL-6 was detected at any dose. Only growth factor FGF-23 was increased in similar pattern to the DNA damage.
We measured 1: the area occupied by a cell and 2: the number of focal adhesions per cell. The largest values of osteoblastic cell area were seen with the smoother vitallium surface. In contrast, samples with more numerous and larger surface features resulted in the osteoblasts covering a smaller area and being confined by topographical elements (Ti2>
TM2F>
Ti6Al4V). In terms of adhesion, there were generally more focal adhesions per cell on rougher surfaces (Ti6Al4V>
TM2F>
Vitallium>
Ti2).
Developments in motion analysis technology over the last two decades have enhanced our understanding of human locomotion. However, such advances in knowledge are futile if no practical use is made of them. Scientists and engineers need to make the most of these developments by forging stronger links with orthopaedic surgeons and applying further advances in their knowledge to clinical problems for the long-term benefit of patients. This need has been identified by many in the field of biomechanics and a “serious attempt [has been made] to take gait analysis out of the research laboratory and into the clinic” (Whittle, 1996 pp.58). For this reason, the aim of this research is to develop an objective and quantitative classification tool that uses motion analysis to aid orthopaedic surgeons and therapists in making clinical decisions. Practical applications of this tool would include joint degeneration monitoring; diagnostics; outcome prediction for surgical intervention; post-operative monitoring and functional analysis of joint prosthesis design. The classification tool (Jones, 2004), based around the Dempster-Shafer theory, is logical and visual; as the progression from obtaining clinically relevant measurements to making a decision can be clearly followed. The current study applies the tool to identify knee osteoarthritis (OA) and post-operative recovery following total knee replacement (TKR) surgery. Knee function data from 42 patients (22 OA and 20 normal (NL)) were collected during a clinical knee trial (Holt et al., 2000). Nine of the OA patients were followed at 3 stages following TKR surgery. Using the tool, a subject’s knee function data are transformed into a set of belief values: a level of belief that the subject has OA knee function, a level of belief that the subject has NL knee function and an associated level of uncertainty. These three belief values are then characterized in a way that enables the final classification of the subject, and the variables contributing to it, to be represented visually. Initial studies using this technique have provided encouraging results for accuracy, validity and clinical relevance (Jones, 2004). The tool was able to differentiate between the characteristics of NL and OA knee function with 98% accuracy. The belief values and simple visual output showed the variation in the extent to which patients had:
developed OA and; recovered after TKR surgery. Furthermore, the visual output enabled straightforward comparison between subjects and indicated the variables that were most influential in the decision making process for comparison with clinical observations and quality of life scores. The tool is generic, and, as such, would be applicable to a wide range of pathological classification and predictive problems.
Leucocytes represent a very important host defence against a number of invading pathogens and neoplasia. However, the activity of phagocytic leucocytes has been heavily implicated in the development of ischaemia-reperfusion injury, and as an aetiological factor in the pathology of other clinically important inflammatory conditions. Ischaemia-reperfusion injury occurs in diseases such as stroke and ischaemic heart disease (IHD), and during surgical procedures such as orthopaedic surgery. Investigations presented here employed a model of tourniquet-induced forearm ischaemia-reperfusion injury to investigate the effect on leucocyte adhesion and trapping (n=20). Neutrophil and monocyte leucocyte subpopulations were isolated by density gradient centrifugation techniques. Neutrophil and monocyte cell surface expression of the adhesion molecule CD11b was measured by labelling with fluorescent anti-CD11b monoclonal antibody via flow cytometry. Plasma concentrations of the soluble intercellular adhesion molecule-1 (sICAM-1) and soluble L-selectin (sL-selectin) adhesion molecules were measured using commercially available ELISA kits. Leucocyte trapping was investigated by measuring the concentration of leukocytes in venous blood leaving the arm. During ischaemia-reperfusion there was an increase in CD11b expression on neutrophils (p=0.040) and monocytes (p=0.049), a decrease in sL-selectin (p=0.387) and sICAM-1 (p=0.089) concentrations, and a decrease in peripheral blood leucocyte concentration (p=0.019). Evidence of increased leucocyte adhesion and trapping during ischaemia-reperfusion injury was supported by an increase in CD11b cell surface expression of neutrophils and monocytes. CD11b is expressed on phagocytic leucocytes and binds to ICAM-1 expressed on the surface of vascular endothelium. This increased expression of CD11b on leucocytes may therefore play a central role as the mechanism by which leucocyte trapping in the microcirculation occurs. The measured decrease in plasma concentration of sICAM-1 and sL-selectin suggests that these adhesion molecules retain their functional activity, and may bind to their corresponding cell surface ligands. It is therefore reasonable to believe that ICAM-1 expressed on the endothelium and L-selectin expressed on leucocytes is also binding to their corresponding cell surface ligands. A decrease in the number of leucocytes in the peripheral circulation may be due to increased trapping of leucocytes in the microcirculation. When leucocytes become trapped their concentration in blood leaving the microcirculation decreases, resulting in the measured decrease in leucocyte concentration. In conclusion, this study confirms the important role of leucocytes during ischaemia-reperfusion injury, which could allow for the possibility of future research that may provide therapeutic intervention for inflammatory conditions.
Patients had improvement of pain, posture, hip instability, walking ability and limb length discrepancy. The median lengthening of the femur was 3 cm (2–5). The mechanical axis was realigned in all patients. All patients were satisfied with the outcome. Planned secondary contra lateral epiphyseodesis was required to equalise leg length in 2 patients. Complications included a stiff knee (1) that required a Judet quadricepsplasty, premature consolidation (1) that required reosteotomy and knee subluxation (1) that required cross knee stabilisation.
We changed our pin tract care practice from 1996. We had a significant decrease in pin tract infections since then (p<
0.0001). We also found that using Ilizarov wires had significantly less infections than with half pins used with monolateral fixators (p<
0.0001; linear trend, p= 0.0338). There were 48 patients that required hospital admissions for IV antibiotics. and of these 10 patients required debridement. There were no residual long lasting infections or chronic osteomyelitis.
We present a series of 48 patients with infected total knee replacements managed by the use of articulating cement spacers and short-term parenteral antibiotic therapy in the postoperative period. All patients had microbiological and/or histological confirmation of infection at the first stage of their revision. They all underwent re-implantation and had a mean follow-up of 48.5 months (26 to 85). Infection was successfully eradicated in 42 of the 48 patients (88%). Six had persistent infection which led to recurrence of symptoms and further surgery was successful in eliminating infection in four patients. These rates of success are similar to those of other comparable series. We conclude that protracted courses of intravenous antibiotic treatment may not be necessary in the management of the infected total knee replacement. In addition, we analysed the microbiological, histological and serological results obtained at the time of re-implantation of the definitive prosthesis, but could not identify a single test which alone would accurately predict a successful outcome.
We reviewed retrospectively 45 patients (46 procedures) with bladder exstrophy treated by bilateral oblique pelvic osteotomy in conjunction with genitourinary repair. The operative technique and post-operative management with or without external fixation are described. A total of 21 patients attended a special follow-up clinic and 24 were interviewed by telephone. The mean follow-up time was 57 months (24 to 108). Of the 45 patients, 42 reported no pain or functional disability, although six had a waddling gait and two had marked external rotation of the hip. Complications included three cases of infection and loosening of the external fixator requiring early removal with no deleterious effect. Mid-line closure failed in one neonate managed in plaster. This patient underwent a successful revision procedure several months later using repeat osteotomies and external fixation. The percentage pubic approximation was measured on anteroposterior radiographs pre-operatively, post-operatively and at final follow-up. The mean approximation was 37% (12% to 76%). It varied markedly with age and was better when external fixation was used. The wide range reflects the inability of the anterior segment to develop naturally in spite of close approximation at operation. We conclude that bilateral oblique pelvic osteotomy with or without external fixation is useful in the management of difficult primary closure in bladder exstrophy, failed primary closure and secondary reconstruction.
It is well appreciated that thigh pain following recent arthroplasty surgery is likely to be due to prosthetic loosening or infection. Both these sequelae can lead to periprosthetic fracture presenting complex challenges to even experienced surgeons. Revision arthroplasty patients are prone to both fatigue and insufficiency fractures as they may have reduced bone stock after previous surgery and reduced bone density secondary to medical and immobility reasons. The post operative painfree condition will frequently permit early load bearing leading to a relatively rapid increase in activity and load bearing. Fatigue fractures occur in bone of normal quality subject to abnormal cyclical overloading, leading to resorption and eventual failure, before adequate time has passed to permit adaptive remodelling. Insufficiency fractures occur when normal physiological loads are applied to bone of abnormal quality. Surprisingly few periprosthetic stress fractures are reported in the literature but a series notes lateral tensile stress fractures associated with varus prosthetic alignment. These all occurred near the tip of the prosthesis. The case of an unusual Gruen Zone 2, Vancouver B1 stress fracture, 9 months following revision arthroplasty is reported. Initially loosening was suspected due to the development of load bearing thigh pain. Plain radiography revealed the development of a dreaded black line, consistent with a stress fracture. Bone scintigraphy revealed the typical appearance of a stress fracture in the absence of loosening or infection. The unusual location of this stress fracture allowed consideration of conservative non weight bearing management which lead to the alleviation of symptoms rather than further revision surgery. This report illustrates this unusual stress fracture and highlights the importance of careful loading practises to permit adequate remodelling following complex revision surgery.
The aim of this study was to determine the inter and intra observer reliability of ultrasound measurements in treated unstable neonatal hips and whether ultrasound measurements correlate with radiological outcome at 6 months. Sixty-four babies treated from birth with a Pavlik harness for neonatal hip instability were scanned at 2 and 6 weeks. The α and β angles of Graf, the combined (H) angle of Hosny and the femoral head coverage (FHC) were measured by 3 observers and inter-observer and intra-observer repeatability co-efficients calculated using 95% confidence limits. Hips were categorized as normal, abnormal or borderline for each parameter and Kappa values calculated. A stepwise linear regression analysis was performed to assess any relationship between ultrasound measurements at 2 or 6 weeks and outcome as determined by acetabular index at 6 months. Seven hundred and ninety two sets of measurements were made from 248 scans. The α angle had the smallest interobserver range (17°), the H angle range was 21°and the β angle 28°. Kappa values showed good agreement for FHC and β angle. The mean acetabular index of all hips at 6 months was 26° (sd 4.9). The acetabular index was 30° or greater in 24 hips (18 babies) despite prolonged splintage in 9 hips (6 babies). The FHC at 6 weeks was predictive of acetabular index at 6 months (regression coefficient −0.27, 95% CI −0.42 to −0.12, p<
0.001) We recommend the FHC as being reproducible, useful and predictive of outcome in neonatal hips treated for instability.
The aim was to compare the initial pull out strengths of various interference screw devices used for tibial fixation of hamstring grafts and the effect of concentric or eccentric screw position. Quadrupled tendon grafts were harvested from freshly killed sheep. The grafts were then prepared and fixed in the distal femur using various devices (Intrafix, RCI screw, Wedge screw +/− transfix pin, screw and post) in both concentric and eccentric positions. A single load to failure test was then performed. The highest pull out strength was with the Intrafix device inserted concentrically (mean 941N). This was significantly higher than the wedge screw inserted concentrically (737N) (p=0.015). This in turn had significantly greater initial pull out strength than the wedge eccentric with post or pin (p=0.03) and the RCI screw (464N) (p=0.00036). In this sheep model the Intrafix device inserted concentrically had a significantly greater initial pull-out strength than the other interference screws tested. Concentric positioning of an interference screw gave significantly greater initial pullout strength of a quadruple hamstring graft than eccentric positioning. Addition of a cross pin or post made no difference to initial pullout strength.
In 20 patients undergoing hybrid total hip arthroplasty, the reproducibility and accuracy of templating using digital radiographs were assessed. Digital images were manipulated using either a ten-pence coin as a marker to scale for magnification, or two digital-line methods using computer software. On-screen images were templated with standard acetate templates and compared with templating performed on hard-copy digital prints. The digital-line methods were the least reliable and accuracy of sizing compared with the inserted prostheses varied between −1.6% and +10.2%. The hard-copy radiographs showed better reproducibility than the ten-pence coin method, but were less accurate with 3.7% undersizing. The ten-pence coin method was the most accurate, with no significant differences for offset or acetabulum, and undersizing of only 0.9%. On-screen templating of digital radiographs with standard acetate templates is accurate and reproducible if a radiopaque marker such as a ten-pence coin is included when the original radiograph is taken.
To investigate the diagnostic properties of magnetic resonance imaging (MRI) scans in detecting surgically verified disruptions of the cervical intervertebral disc and anterior (ALL) and posterior longitudinal (PLL) ligaments. Data were extracted from the reports of cervical spine MRI scans of patients who subsequently underwent surgical stabilization for presumed instability following disco-ligamentous injuries of the cervical spine. The level and severity of disc, ALL and PLL disruption was compared with surgical findings. Unweighted kappa statistics were used to assess agreement. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values were calculated after findings where dichotomised into complete rupture, yes/no. Sensitivity analyses were performed to account for missing data. The MRI and surgical findings were compared on 31 consecutive patients. The kappa values for intervertebral disc disruption, ALL and PLL disruption were 0.22, 0.25 and 0.31 respectively, indicating fair agreement. Sensitivity, specificity, PPV and NPV are shown in Table 1. The false negative rates for diagnosing complete disruption of the disc, ALL and PLL were 0.18, 0.40 and 0.14 respectively. The ability of cervical MRI scans to detect surgically verified disruptions of the intervertebral disc, ALL and PLL varied depending on the structure examined. In this series, the cervical MRI scan reliably detected disruption of the intervertebral disc disruption and ALL. The false negative rates are of concern and indicate the need for additional investigations to exclude instability in the absence of negative MRI findings.
To reduce the disability after hip disarticulation customised endoprostheses have been used in our unit to preserve a proximal femoral above knee amputation stump. This procedure involves preservation of a musculocutaneous flap and insertion of a customised stump prosthesis that articulates with the acetabulum. This procedure has been performed not only for primary malignancy but also in the reconstructive setting. Six patients have undergone the above procedure with a good functional outcome-allowing mobilisation with an appropriate orthosis. We will discuss the complications of such a procedure that includes disassociation of the femoral head from the customised prosthesis. We present the technique as a useful adjunct not only in the treatment of large proximal femoral tumours but also in the end stage reconstructive setting.
This lady noticed a recent change in the gait and examination revealed positive trendelenberg test and a lurching gait. Latest radiographs have shown a fracture of the left iliac crest. The patient did not request any surgical intervention and was reassured with explanation.
The aim was to audit the numbers of non-residents requiring orthopaedic admission to our hospital and determine the effect of increasing tourist numbers and changes in Accident Compensation Corporation (ACC) regulations on health care resources. Details of non-resident orthopaedic admissions for fiscal years 1997/8 to 2003/4 were analysed with respect to country of residence, mechanism of injury, case weights consumed and actual costs. There has been no change in numbers of admissions or cost averaging 32 cases (50 case weights) per year over the 7 year period. Most patients came from Asia (59 cases, 26%), then Australia (52 cases, 23%) and UK (40 cases 18%). Snowsports accounted for 40% of admissions, Motor vehicle accidents (MVA)17% and falls 29%. Non-resident, non-MVA admissions have averaged 21 CW per year since the changes in ACC regulations in 1999. Despite increasing tourist numbers there has been no increase in numbers or CW of non-residents requiring orthopaedic admission. Although representing only a small proportion of the orthopaedic budget they generate many hidden costs. The 50 CW annually equates to approximately 13 major joint replacements per year. The increase in CWs consumed due to the ACC changes have had no corresponding increase in contracted orthopaedic volumes.
All patients underwent staging and follow up at Sarcoma Clinic with functional assessment and TESS evaluation.
Nine patients underwent planned marginal excision. Sciatic nerve involvement was 13–30cm in eight cases and in one case the sciatic nerve was abutting the tumour throughout its length. There was soft tissue reconstruction in three cases using fascial adductor or gracilis graft for sciatic nerve cover and one with superficial femoral nerve and vein resection requiring ipsilateral saphenous reconstruction. The remainder underwent direct primary reconstruction. Four patients underwent radiotherapy 46–60 Gy. There was no local recurrence of disease within 14 – 96m follow-up. There was one patient with post radiation wound breakdown that resolved. Three patients have died of unrelated causes. To date there has been no evidence of local recurrence of disease at FU.
The aim of this study was to prospectively audit the results of carpal tunnel decompression using a subjective patient derived outcome score (modified Boston Symptom Severity Score) and to examine the relationship between symptom severity scores and nerve conduction studies. Prospective cohort study of all patients undergoing open carpal tunnel decompression at Dunedin Hospital over a 13-month period from December 2003 – January 2005. Demographic details collected included age, sex, duration of symptoms, diabetes, occupation and ACC status. Pre-operative investigations consisted of nerve conduction studies and a modified version of the Boston Symptom Severity Score developed for this study. Symptom severity scores were reassessed six months post-operatively. One hundred and ten patients participated in the study. Mean pre-operative Boston Symptom Severity Score was 3.35 (1= normal, 5=severe). Post-operatively this improved to mean 1.66, median 1.45. Ninety three percent of patients were “very satisfied” or “satisfied” with their results. Age and duration of symptoms were not significant predictors of poor outcome. The majority of patients undergoing carpal tunnel decompression were satisfied with the outcome and had excellent or good outcomes as determined by symptom severity score. The use of preoperative nerve conduction studies help in diagnosis and prognosis.