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Volume 94-B, Issue SUPP_XVIII May 2012 British Orthopaedic Research Society (BORS)

K Imagawa H I Roach

In osteoarthritis (OA), articular chondrocytes undergo a phenotypic change and acquire a gene expression repertoire that is characterized by the aberrant expression of numerous catabolic genes including matrix metalloproteinases 3, 9 and 13, ADAMTS-4 and interleukin-1beta (IL1B = gene, IL-1b=protein). Previous studies (Arthritis Rheum 52;3110-24) have shown that epigenetic DNA demethylation at specific CpG sites in the relevant promoters accounts for the aberrant expression and that inflammatory cytokines (TNF-alpha, oncostatin M, IL-1b) can cause both aberrant expression and loss of DNA methylation, at least in vitro (Arthritis Rheum. 2009, 60,3303-3313). If the mechanisms of DNA de-methylation were understood, they might provide a new molecular target for therapeutic intervention. We hypothesize that nuclear translocation of the transcription factor NF-kB is involved in de-methylation because 1) we and others have demonstrated that cytokine-induced expression of IL1B in healthy chondrocytes requires NF-kB and 2) DNA de-methylation during B cell maturation was crucially dependent on the rel/NF-kB family (Nat Genet. 1996, 13,435-441). The aims of the study were to determine whether the NF-kB inhibitor BAY 11-7082 (BAY) could prevent the cytokine-induced loss of DNA de-methylation and thereby show that NF-kB is required for DNA de-methylation.

METHODS

Healthy chondrocytes were isolated from the articular cartilage of six femoral heads, obtained with ethical permission after operations following neck of femur fractures. Chondrocytes were cultured for 5 weeks in 4 separate groups: without treatment (control culture); with 2.5ng/ml IL-1b and 2.5ng/ml oncostatin M (IL-1b+OSM); with 1.0mM BAY alone; and IL-1b+OSM+BAY. Total RNA and genomic DNA were extracted from each sample. Gene expression of IL1B was determined by SybrGreen-based qRT-PCR. The % DNA methylation at a specific CpG site in the IL1B promoter (which had previously been identified as a crucial CpG site) was quantified after bisulfite modification with a pyrosequencer (Biotage). The data for IL1B expression and % DNA methylation were analyzed in Microsoft Excel using Wilcoxon's signed rank test. P values < 0.05 were considered significant.

RESULTS

Although there was considerable variation between samples, expression of IL1B was increased by > 1000 fold in the IL-1b+OSM group compared with control culture, confirming previous results. When BAY was present together with IL-1b+OSM, the increase in IL1B expression was reduced from ∼1000-fold to ∼200-300-fold (P< 0.01). In addition, the % DNA methylation had changed. At the -299 CpG site of IL1B promoter the % methylation was 57% in control culture and 60% in the BAY alone group. IL-1b+OSM caused a decrease to 37% (P<0.01 compared with all other groups), whereas presence of BAY prevented this loss, since the % methylation was 58% in IL-1b+OSM+BAY group.


M.C. de Andrés H.I. Roach

BACKGROUND

Although osteoarthritis (OA) is not an inflammatory arthritis, a characteristic feature of OA is increased production of pro-inflammatory cytokines, such as interleukin 1beta (IL-1b), by articular chondrocytes. In fact, the degree of articular inflammation is often associated with disease progression; indicating that this process probably contributes to articular damage. Suppressor of cytokine signalling (SOCS) proteins are, as the name suggests, inhibitors of cytokine signalling that function via the JAK/STAT pathway (Janus kinase/signal transducers and activators of transcription). Eight SOCS proteins, SOCS1-SOCS7 and CIS-1 (cytokine-inducible SH2-domain-1 with similar structure to the other SOCS proteins) have been identified, of which, SOCS1-3 and CIS-1 are the best characterised. Reduced expression of SOCS proteins would be predicted to result in increased cytokine responsiveness and thereby could contribute to OA pathology.

OBJECTIVES

1) To compare the expression of SOCS1-3 and CIS-1 in normal and OA human articular chondrocytes and 2) to analyze the effects of IL-1b on SOCS1-3 and CIS-1 mRNA expression.


R. EL-Gendy A.R. Boccaccini P. Newby J. Kirkham X.B. Yang

Stromal cells derived from human dental pulp (HDPSCs) are of current interest for applications in skeletal tissue engineering. Angiogenesis and revascularization of bone grafts or bone constructs in vivo are of paramount importance for bone tissue regeneration and/or fracture healing. The aim of this study was to investigate the angiogenic and osteogenic potential of HDPSCs in combination with Bioglass¯ scaffolds in vitro and in vivo.

HDPSCs, isolated by collagenase digestion, were either maintained as monolayers or dynamically seeded on 3D Bioglass¯ scaffolds and cultured under either basal or osteogenic conditions for 2 and 4 weeks. Expression of osteogenic (COL1A1, ALP, RUNX2 and OC) and angiogenic markers (VEGFR2, CD34 and PECAM1) was determined using qRT-PCR. Alternatively, constructs were either cultured in vitro under basal/osteogenic conditions for 6 weeks or sealed in diffusion chambers which were then implanted intraperitoneally in immunosuppressed mice for 8 weeks. Retrieved constructs were fixed and embedded for histology and immunohistochemistry using antibodies against COL1, RUNX2, OC, VEGFR2, CD34 and PECAM1. qRT-PCR showed no significant differences in gene expression of osteogenic markers between basal and osteogenic media for both 3D construct and monolayers.

However when comparing 3D constructs to monolayers: COL1A1 showed a significantly lower expression (p< 0.05) in 3D compared to 2D at 2 weeks in both culture conditions, and this pattern was reversed after 4 weeks. ALPL was significantly lower in 3D constructs at 2 weeks under both conditions (p<0.01), and was significantly higher in basal conditions at 4 weeks (p<0.05). RUNX2 showed higher expression in 3D constructs at all time points and under both conditions while OC showed lower expression in 3D constructs at 2 weeks and higher expression at 4 weeks under both conditions. For the angiogenic markers, 3D constructs under osteogenic conditions showed an increase of expression in VEGFR2 and PECAM1 at 2 weeks followed by a decrease at week 4, while CD34 expression was undetected in 3D constructs at all times and under both sets of culture conditions. The expression of VEGFR2 and PECAM 1 under both conditions and at both time points was greater in 3D constructs compared to monolayers. After 8 weeks, the in vivo retrieved constructs showed no signs of inflammatory reactions. Immunohistology confirmed positive staining of osteogenic and angiogenic markers in 3D constructs from both in vitro and in vivo experiments with a greater staining intensity seen in the in vivo constructs. Furthermore, the in vivo constructs showed more intense sirius red staining and higher intensity of immunostaining using antibodies to type 1 collagen, with higher calcification as indicated by alizarin red staining.

In conclusion, this study indicated that a combination of HDPSCs and Bioglass¯ scaffolds has potential to provide a suitable microenvironment for angiogenic and osteogenic differentiation of HDPSCs which is essential for bone regeneration in preclinical and/or clinical applications.


D.J. Simpson B. Kendrick M. Hughes G.F. Rushforth H.S. Gill D.W. Murray

Introduction

Primary mechanical stability is important with uncemented THR because early migration is reduced, leading to more rapid osseointegration between the implant and bone. Such primary mechanical stability is provided by the design features of the device. The aim of this study was to compare the migration patterns of two uncemented hip stems, the Furlong Active and the Furlong HAC stem; the study was designed as a randomised control trial. The implants were the Furlong HAC, which is an established implant with good long term results, and the Furlong Active, which is a modified version of the Furlong HAC designed to minimise stress concentrations between the implant and bone, and thus to improve fixation.

Materials and methods

The migration of 43 uncemented femoral components for total hip replacement was measured in a randomised control trial using Roentgen Stereophotogrammetric Analysis (RSA) over two years. Twenty-three Furlong HAC and twenty Furlong Active stems were implanted into 43 patients. RSA examinations were carried out post-operatively, and at six months, 12 months and 24 months post-operatively. The patients stood in-front of a purpose made calibration frame which contained accurately positioned radio-opaque markers. From the obtained images, the 3-D positions of the prosthesis and the host bone were reconstructed. Geometrical algorithms were used to identify the components of the implant. These algorithms allowed the femoral component to be studied without the need to attach markers to the prosthesis. The migration was calculated relative to the femoral coordinate system representing the anterior-posterior (A-P), medial-lateral (M-L) and proximal-distal (P-D) directions respectively. Distal migration was termed subsidence.


G. Cox D. McGonagle S. Boxall C. Buckley E. Jones PV. Giannoudis

Introduction

Therapeutic exploitation of MSCs in orthopaedics has been tempered by their scarcity within ‘gold-standard’ iliac crest bone marrow aspirate (ICBMA) and the resulting need to expand cells in vitro. This is time-consuming, expensive and results in cells with a reduced differentiation capacity. [Banfi 2000] The RIA is a device that provides continuous irrigation and suction during reaming of long bones. Aspirated contents pass via a filter, trapping bony-fragments, before moving into a ‘waste’ bag, from which MSCs have been previously isolated. [Porter 2009] We hypothesised that ‘waste’ RIA bag contains more MSCs than a standard aspirated volume of ICBMA (30 ml). We further hypothesised than a fatty solid phase within this ‘waste bag’ contains many MSCs trapped within the adipocyte-rich stromal network and hence requiring an enzymatic digestion for their efficient release [Jones 2006].

Methods

The discarded filtrate ‘waste’ bag that contained saline from marrow cavity irrigation procedure from RIA reaming (7 patients) was filtered (70μm) and the solid fraction digested for 60min (37oC) with collagenase. MSC enumeration was performed using the colony-forming-unit-fibroblast (CFU-F). Following culture in standard expansion media, passage 2 cells were differentiated towards osteogenic, adipogenic and chondrogenic lineages and their phenotype was assessed using flow cytometry. ICBMA from the same patients was used as controls.


S. Franklin N. Zargar K. Willett P. Hulley M. Thompson

Introduction

The use of platelet-rich concentrate (PRC) to enhance the healing response in tendon repair is currently an area of considerable interest. Activated platelets release a cocktail of growth factors and ECM regulating molecules. Previous work suggests that tenocytes are activated by contact with these clot-derived molecules. Our studies on tenocytes and PRC aim to establish the direct molecular and functional effects of PRC on tenocytes and to support the clinical research on Achilles tendon repair taking place within our group. We hypothesise that applying PRC to human tenocytes in culture will increase proliferation rate and survival by activating relevant signalling pathways.

Materials and Methods

Using a centrifugation method, PRC was extracted from fresh human whole blood. The PRC was immediately clotted and left in medium overnight to release biological factors (at least 95% of presynthesized growth factors are secreted in the first hour of activation)1. Human tenocytes derived from explanted healthy hamstring were used for up to three passages. Cells were treated with varying concentrations of PRC-conditioned medium and assessed for viable cell number (Alamar Blue™ fluorescence) and proliferation (Ziva™ Ultrasensitive BrdU assay) after 72hrs. For western blotting, cells were treated with 10% PRC for 5 or 30 minutes. Antibodies to P-ERK and P-Akt detected the active protein state on the blot, followed by membrane stripping and re-probing with pan antibodies. Quantification was achieved by densitometry using Visionworks software v. 6.7.1.


K. Shu D.A. Kendall V. Chapman D. Barrett W. Jeffcoate A. Bennett B.E. Scammell

Introduction

Both the RANK/RANKL system and the endocannabinoid system have roles in bone remodelling. Activation of CB1 receptors on sympathetic nerve terminals in trabecular bone modulates bone remodelling by attenuating adrenergic inhibition over bone formation. CB2 receptors are involved in the local control of bone cell differentiation and function. Osteoblastic CB2 receptor activation negatively regulates RANKL mRNA expression indicating an interaction between the two systems and that efficient bone remodelling requires a balance between these two systems. The aim of the study was to establish the presence of the different components of the endocannabinoid system and the RANK/RANKL signalling pathway in human bone and osteoclast culture.

Methods

Levels of endocannabinoids (AEA, 2-AG) and their related compounds (OEA, PEA) in human trabecular bone, obtained from patients undergoing elective orthopaedic surgery, were measured using Liquid Chromatography Mass Spectrometry (LC-MS-MS). mRNA for the endocannabinoid synthetic and catabolic enzymes (NAPE-PLD, DAGLa, FAAH, MAGL), cannabinoid-activated receptors (CB1, CB2, PPARs, TRPV1), and RANK, RANKL and NFkB were determined using Taqman Real-Time PCR. Osteoclasts were differentiated from U-937 cells (Human leukaemic monocyte lymphoma cell line), following the sequential treatment using TPA (0.1μg/ml) followed by either TNF-a (3ng/ml) or calcitriol (10−8M), cultured for up to 30 days. Osteoclasts were identified by positive staining with tartrate resistant acid phosphatase (TRAP), multinucleation and the ability to form resorption pits on calcium phosphate coated discs. Taqman Real-Time PCR was performed to detect the expression of the osteoc!

last marker genes TRAP and cathepsin K, together with genes of the endocannabinoid and RANK/RANKL signalling pathways.


HC Roberts S Paisey P Jemmett PD Hodgson C Wilson DJ Mason

Osteoarthritis (OA)

is the most common arthritic condition. OA causes joint pain, loss of mobility and significantly affects the quality of life for the affected individual. The major burden to patients with arthritis is pain. However, often radiological joint destruction and the extent of pain do not correlate. This causes a dilemma for clinicians in advising timing for joint replacement surgery. In arthritis, concentrations of the neurotransmitter, glutamate is increased within the synovial fluid activating both peripheral pain mechanisms and pathological processes (1). Other pathological/pain related metabolites are also released into synovial fluid, which provides a real time snap shot of the joint pathology. We have tested the hypothesis that ‘The increased levels of pain and disease-related metabolites within human synovial fluids from arthritic joints can be detected and quantified ex vivo using high resolution 1H-NMR.’

Method

OA synovial fluid samples were obtained during arthroscopy or total knee replacements from patients with varying degrees of pain and pathology (cartilage graded 0-4; n=21). Pain perception was determined using the Oxford knee score and samples sub-classified as mild, moderate and severe pain. All samples were analysed using 500 MHz 1H NMR spectroscopy. Chemical shifts were referenced to a known concentration NMR internal standard (TSP), peaks identified by reference to published synovial fluid NMR spectra (2) and peak integrals measured using the Bruker software Topspin 2.0.

Results: Using NMR we were able to detect around 26 metabolite-specific peaks in synovial fluid spectra (such as glutamate/glutamine, isoleucine, acetyl glucoproteins, beta-hydroxbutyrate, CH2 lipids, lactate, glucose). Some specific metabolites varied significantly with pain or pathological score. For example, we found significantly more glutamate/glutamine, isoleucine and beta-hydroxybutyrate (p<0.05, T test) in OA samples reporting mild to moderate levels of pain (n=14) compared to severe pain (n=7). Significantly more CH2 lipids (p<0.05, T-test) were also present in samples indicating severe pain compared to mild/moderate pain.


A. Dhillon B.E. Scammell K. Shakesheff

Background/Study Aim

Injectable scaffolds which also deliver cells and bioactive molecules to augment bone healing overcome many of the limitations associated with current bone graft substitutes. The aim of this study was to develop and test a novel injectable scaffold that self-assembles isothermically in situ to form a biodegradable porous osteoconductive material, and to assess the viability of human mesenchymal stem cells (hMSC) seeded onto the scaffold.

Methods

Rheological assessment was performed on three different molecular weights (Mw) of poly(lactic-co-glycolic acid) (PLGA) (26kDa, 53kDa and 92kDa) combined with differing ratios of polyethylene glycol (PEG) to control the temperature required for scaffold self-assembly. The strength (MPa) and stiffness (Young's Modulus) patterns of the scaffolds were assessed in compression. The cell viability, proliferation and distribution patterns of hMSCs seeded within the scaffold were assessed through various assays (Alamar Blue), confocal microscopy and micro-CT. The hMSC differentiation in osteogenic media was characterised by the identification of specific bone formation markers (e.g. alkaline phosphatase).


S Chaudhury C Holland D Porter F Vollrath A J Carr

Improved understanding of the biomechanics and biology of rotator cuff tendons (RCT) may help reduce high re-rupture rates following repairs, particularly amongst larger tears. This study aims to use novel methods for quantitatively determining differences in the mechanical and thermal properties of intact healthy RCTs compared to torn ‘diseased’ tendons. A common problem in the mechanical testing of small tendon samples is that stress risers at the clamp-tendon interface can obscure measurements. As the shoulder is subject to shear, tension and compression, we developed a novel solution using Dynamic Shear Analysis (DSA), a form of rheology which studies material deformation. As collagen is the main component of RCT, the structure and mechanical properties may be affected by collagen conformational changes. Both dermis and rat tail tendon with increased collagen cross-linking exhibit stronger mechanical properties. Thermal changes detected by differential scanning calorimetry (DSC) can help to quantify collagen structural differences in torn RCT, and has been previously used to study muscle, cartilage and vertebral discs.

There were 79 tears (mean age 65.2 years), which were classified according to the size of the tear as small, medium, large and massive. Two separate 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression. The storage modulus (G') was calculated and used as an indicator of mechanical integrity. 18 control tendon specimens were obtained from patients aged between 22-89 years (mean age 58.8 years) during shoulder hemiarthroplasties and stabilisations. Additionally 7 normal, 7 small and 7 massive frozen specimens were thermally characterized. 3 samples per patient were heated between 20-80oC in hermetically sealed vessels. Useful thermal parameters were measured such as the melting temperature (TM) which apparently represents breaking of the amide-amide bonds and protein chains mobility, the denaturation temperature (TD) which supposedly corresponds to proteins falling out of solution and the denaturation enthalpy (ΔH) which reflects the relative amount of triple helical structure.

Healthy tendons had a significantly higher modulus than torn tendons, indicating that torn tendons are mechanically weaker than normal tendons (p = 0.032). Normal tendons had significantly higher mean shear modulus than tendons with small and massive tears (p<0.01). Overall there was a negative correlation between moduli and severity of tendon tear (r = −0.698, p=0.189). The moduli did not significantly correlate with age, sex, hand dominance, or length of preservation in formalin. Massive RCT tears had significantly higher TM and TD when compared to normal RCT (p < 0.05), unlike small RCT tears. No significant difference was detected between the denaturation enthalpy of the different RCT groups. This case control study has demonstrated that normal RCTs have a significantly higher modulus than torn tendons, indicating that torn tendons have less mechanical integrity. Our study further demonstrated a trend between increasing tear size and decreasing mechanical integrity. This study has also demonstrated differences in some of the thermal properties of normal and torn RCTs. These are likely due to collagen structural changes. A decrease in the denaturation temperature of torn tendons, suggests that the material is intrinsically less stable. Torn tendons with reduced storage modulus and collagen integrity may be less able to withstand mechanical loads following repair. This pilot study provides some preliminary insight into the mechanisms that may contribute to, or represent adaptations to high rates of failure of RCT repairs.


J.L. Tipper R.E. Vicars T.D. Brown E. Ingham J. Fisher R.M. Hall

Introduction

The biological response to UHMWPE particles generated by total joint replacements is one of the key causes of osteolysis, which leads to late failure of implants. Particles ranging from 0.1-1.0μm have been shown to be the most biologically active, in terms of osteolytic cytokine release from macrophages [1]. Current designs of lumbar total disc replacements (TDR) contain UHMWPE as a bearing surface and the first reports of osteolysis around TDR in vivo have appeared recently in the literature [2]. The current wear testing standard (ISO18192-1) for TDR specifies only four degrees of freedom (4DOF), i.e. axial load, flexion-extension, lateral bend and axial rotation. However, Callaghan et al. [3] described a fifth DOF, anterior-posterior (AP) shear. The aim of this study was to investigate the effect that this additional AP shear load component had on the size and morphology of the wear particles generated by ProDisc-L TDR devices over five million cycles in a spine simulator.

Methods

A six-station lumbar spine simulator (Simulation Solutions, UK) was used to test ProDisc-L TDR components (Synthes Spine, USA) under the ISO 18192-1 standard inputs and with the addition of an AP load of +175 and −140N. Wear particles were isolated at 2 and 5 mc using a modified alkaline digestion protocol [4]. Particles were collected by filtration and imaged by high resolution FEGSEM. Particle number and volume distributions were calculated as described previously [4] and were compared statistically by one way ANOVA (p<0.05).


D. J. Simpson B. Kendrick A. J. Price D.W. Murray H.S. Gill

Introduction

Unicompartmental Knee Replacement (UKR) is an appealing alternative to Total Knee Replacement (TKR) when the patient has isolated compartment osteoarthritis (OA). A common observation post-operatively is radiolucency between the tibial tray wall and the bone. In addition, some patients complain of persistent pain following implantation with a UKR; this may be related to elevated bone strains in the tibia. The aim of this study was to investigate the mechanical environment of the tibia bone adjacent to the tray wall, following UKR, to determine whether this region of bone resorbs, and how altering the mechanical environment affects tibia strains.

Materials and methods

A finite element (FE) model of a cadaver tibia implanted with an Oxford UKR was used in this study, based on a validated model. A single static load, measured in-vivo during a step-up activity was used. There was a 1 mm layer of cement surrounding the keel in the cemented UKR, and the cement filled the cement pocket. In accordance with the operating procedure, no cement was used between the tray wall and bone. For the cementless UKR a layer of titanium filled the cement pocket. An intact tibia was used to compare to the cemented and cementless UKR implanted tibiae. The tibia was sectioned by the tray wall, defining the radiolucency zone (parallel to the vertical tray wall, 2 mm wide with a volume of 782.5 mm3), corresponding to the region on screened x-rays where radiolucencies are observed. Contact mechanics algorithms were used between all contacting surfaces; bonded contact was also introduced between the tray wall and adjacent bone, simulating a mechanical tie between them. Strain energy density (SED), was compared between the intact and implanted tibia for the radiolucency zone. Equivalent strains were compared on the proximal tibia between the intact and implanted tibia models. Forty patients (20 cemented, 20 cementless) who had undergone UKR were randomly selected from a database, and assessed for radiolucency.


H.A. Gray A.B. Zavatsky H.S. Gill

Iterative finite element (FE) models are used to simulate bone remodelling that takes place due to the surgical insertion of an implant or to simulate fracture healing. In such simulations element material properties are calculated after each iteration of solving the model. New material properties are calculated based on the results derived by the model during the last iteration. Once the FE model has gone through a number of such iterations it is often necessary to assess the remodelling that has taken place. The method widely used to do this is to analyse element Young's modulus plots taken at particular sections through the model. Although this method gives relevant information which is often helpful when comparing different implants, the information is rather abstract and is difficult to compare with patient data which is commonly in the form of radiographs.

The authors suggest a simple technique that can be used to generate synthetic radiograph images from FE models. These images allow relatively easy comparisons of FE derived information with patient radiographs. Another clear advantage of this technique is that clinicians (who are familiar with reading radiographs) are able to understand and interpret them readily.

To demonstrate the technique a three dimensional (3D) model of the proximal tibia implanted with an Oxford Unicompartmental Knee replacement was created based on CT data obtained from a cadaveric tibia. The model's initial element material properties were calculated from the same CT data set using a relationship between radiographic density and Young's modulus.

The model was subject to simplified loading conditions and solved over 365 iterations representing one year of in vivo remodelling. After each iteration the element material properties were recalculated based on previously published remodelling rules. Next, synthetic anteroposterior radiographs were generated by back calculating radiographic densities from material properties of the model after 365 iterations. A 3D rectangular grid of sampling points which encapsulated the model was defined. For each of the elements in the FE model radiographic densities were back calculated based on the same relationships used to calculate material properties from radiographic densities. The radiographic density of each element was assigned to all the sampling grid points within the element. The 3D array of radiographic densities was summed in the anteroposterior direction thereby creating a 2D array of radiographic densities. This 2D array was plotted giving an image analogous to anteroposterior patient radiographs. Similar to a patient radiograph denser material appeared lighter while less dense material appeared darker.

The resulting synthetic radiographs were compared to patient radiographs and found to have similar patterns of dark and light regions.

The synthetic radiographs were relatively easy to produce based on the FE model results, represented FE results in a manner easily comparable to patient radiographs, and represented FE results in a clinician friendly manner.


M.A. Accardi D. Dini N.H. Lim K. Yamamoto P.M. Cann

INTRODUCTION

Osteoarthritis (OA) can be artificially simulated ex vivo on healthy articular cartilage (AC) samples by use of proteolytic enzymes. In this article we will present preliminary analyses of the physical degradation of AC when subjected to alternating mechanical stresses. Since AC damage due to OA is believed to be mechanically induced, the first step towards the realisation of an improved understanding of degenerative behaviour of AC under physiological loading conditions is to perform ex vivo tests which mimic such conditions at best.

METHODS

Porcine AC was subjected to biochemical stimulation or left as native AC. Biochemical degradation was performed using combinations of trypsin and Matrix Metalloproteinases (MMPs) to induce the loss of proteoglycan and collagen. A comparison of the biochemical and mechanical properties, topography and difference in response to mechanical damage between the digested AC and healthy AC was made using White Light Interferometry (WLI), Atomic Force Microscopy (AFM) and mechanical testing. The mechanical damage was induced by subjecting AC to shear under physiological and non physiological conditions. The AC was mechanically tested in a Phosphate Buffered Saline (PBS) bath. After mechanical testing, biochemical analysis of the collagen and aggrecan content of the tissue and PBS present in the bath during the mechanical test was performed. Collagen content was determined by measurement of the amount of hydroxyproline (HPRO), and aggrecan content by the amount of glycosaminoglycans (GAG). The mechanical test was either performed on healthy (native) AC or on AC which had first been digested.


K. Button R.W.M. Van Deursen

Following acute ACL rupture patients are routinely referred for rehabilitation but the timing and level of functional recovery related to rehabilitation outcome are poorly defined.

The primary aim of this study was to measure functional recovery following acute ACL rupture in the clinical setting using a two dimensional movement analysis system. A longitudinal research design was used; we aimed for three clinical movement analysis sessions over the course of rehabilitation. One hundred and fifteen patients were recruited. Sixty three uninjured matched controls were recorded once performing all the functional activities; walking, jogging, distance hop and run and stop. Participants were filmed in the sagittal plane using a digital camcorder to extract kinematic data. Average recovery over time was modelled using a least squares third order polynomial.

The secondary aim was to define the outcome measures and treatment goals used in ACL rehabilitation by specialist knee physiotherapists. A questionnaire was distributed to 300 hospitals across the UK. From the 44 responses insight was obtained about parameters physiotherapists use to plan treatment and evaluate recovery.

Repeated movement analysis showed that gait velocity took on average 85 days to recover to within the normal limits of uninjured controls. Jogging velocity took 30 days; Hop distance took 55 days for the non-injured leg and 100 days for the injured leg; Knee range during the landing phase of run and stop took 80 days to recover but demonstrated some deterioration. The questionnaire identified that specialist knee physiotherapists use 60 different outcome measures and 34 rehabilitation treatment goals, which can be sub-divided into patient reported (PR), functional activities (A) and impairments (I). The percentage usage by physiotherapists for each category of outcome measure were 55.8% (A), 62.8% (I) to 67.4% (PR) and for treatment goals 55.8% (PR), 69.8% (A) to 81.4% (I). Hopping is the most frequently evaluated functional activity but there are large differences in its utilisation. The application of functional goals and outcome measures in rehabilitation is not universal with specialist physiotherapists generally adopting an impairment approach.

Repeated movement analysis in the clinical setting provided objective data on the recovery of functional activities that progressively challenge knee stability. Gait and hop distance appear to be the most useful variables for tracking performance over time but their predictive value needs to be explored further. Adaptations in the non-injured leg indicate that its use as a control needs to be done with caution. For jogging and run and stop there appears to be a threshold after which patients can perform these activities rather than a gradual recovery. Clinical movement analysis could be used to provide objective feedback on recovery levels and help guide the rehabilitation process. However, currently functional goals and milestones are not always included in the planning and evaluation of rehabilitation. Developing better rehabilitation should involve greater integration of functional activity measures into practice. This would require a shift from an impairment rehabilitation approach to focus on functional goals.


K. Brakspear P. Parsons D.J. Mason

Mechanical loading is a potent stimulator of bone formation. A screen for genes associated with mechanically-induced osteogenesis implicated the glutamate transporter GLAST-1 (1), in the mechanoresponse. We are investigating whether modulation of glutamate transporters represents a potential anabolic therapy in bone. Bone cells express functional components from each stage of the glutamate signalling pathway and activation of ionotropic glutamate receptors on osteoblasts can increase bone forming activity (2). Five high affinity Na+-dependant excitatory amino acid transporters (EAATs 1-5) regulate glutamatergic signalling. EAAT1 (GLAST-1) is expressed by osteocytes and bone-forming osteoblasts in vivo.

We quantified transcripts for EAATs 1-3 and two splice variants (EAAT1a and EAAT1ex9skip) in human osteoblasts (MG63, SaOS-2 and primary) using real time-PCR. EAAT1a expression was very low whilst levels of the dominant negative EAAT1ex9skip were much higher in all cell types. EAAT1 and EAAT3 proteins were detected by immunofluorescence. We also demonstrated that glutamate transporters function in human osteoblasts. Sodium-dependent 14C-labelled glutamate uptake, sensitive to pharmacological EAAT inhibitors (t-PDC, TBOA) and extracellular glutamate concentration (10-500μM) was detected in MG63 and SaOS-2 cells.

To determine whether modulation of EAATs can influence bone formation, we used pharmacological inhibitors of EAATs 1-5 (t-PDC and TBOA) and also over-expressed EAAT1exon9skip using antisense oligonucleotides (AONs) targeted to splice donor sequence of exon 9. Experiments were performed in 0-500μM glutamate. Pharmacological inhibition of EAATs over 5-21 days increased alkaline phosphatase activity and mineralisation of SaOS-2 cells and human primary osteoblasts. Over-expression of EAAT1ex9skip significantly increased cell number and decreased cell death as well as significantly increasing PCNA, Osteonectin and Type I collagen mRNAs in MG63 cells. Furthermore, over-expression of EAAT1ex9skip increased mean alkaline phosphatase activity over 48hrs in SaOS-2 cells.

These data show that EAATs are expressed and functional in osteoblasts and that pharmaceutical and genetic inhibition of their activity increases bone formation. These mechanically regulated glutamate transporters are important in regulating bone homeostasis and their manipulation may represent a new anabolic therapy for the treatment of disorders such as osteoporosis or non-union fractures.


WS Khan S Dheerendra DS Johnson JG Andrew TE Hardingham

INTRODUCTION

Bone marrow derived mesenchymal stem cells are a potential source of cells for the repair of articular cartilage defects. Hypoxia has been shown to improve chondrogenesis in adult stem cells. In this study we characterised bone marrow derived stem cells and investigated the effects of hypoxia on gene expression changes and chondrogenesis.

MATERIALS AND METHODS

Adherent colony forming cells were isolated and cultured from the stromal component of bone marrow. The cells at passage 2 were characterised for stem cell surface epitopes, and then cultured as cell aggregates in chondrogenic medium under normoxic (20% oxygen) or hypoxic (5% oxygen) conditions for 14 days. Gene expression analysis, glycosoaminoglycan and DNA assays, and immunohistochemical staining were determined to assess chondrogenesis.


Sarah JB Snelling Rose K Davidson Tracey E Swingler Andrew J Price Ian M Clark

Purpose

To identify genes showing altered expression in osteoarthritic (OA) cartilage and synovium. Dkk3, a member of the Dickoppf family of Wnt signalling inhibitors was overexpressed and this work highlights the potential function of Dkk3 in OA.

Methods

Real-time PCR was used to compare the expression of 270 cytokines, chemokines and their receptors in cartilage and synovium from OA and non-OA patients. Expression of Dkk3 was also measured in ATDC5 cells and in bovine nasal cartilage (BNC) explants treated with inflammatory cytokines. The effect of Dkk3 on hydroxyproline and GAG release was measured in BNC explant cultures.

To assess the distribution of Dkk3 in OA cartilage immunohistochemistry was carried out on anteromedial gonarthrosis specimens. The level of Dkk3 in synovial fluid tricompartmental and unicompartmental cartilage lesions was measured using ELISA.


Y. Mohanram J. Kirkham X.B. Yang

Introduction

P-15 (GTPGPQGIAGQRGVV), a fifteen residue synthetic peptide, is a structural analogue of the cell binding domain of Type 1 collagen and creates a biomimetic environment for bone repair when immobilized on anorganic bovine mineral (ABM) scaffolds. ABM-P-15 scaffolds have been shown to enhance bone marrow stromal cell growth and differentiation. This study aimed at evaluating the osteogenic potential of human dental pulp stromal cells (HDPSCs) compared to human bone marrow stromal cells (HBMSCs) in monolayer and on 3D ABM-P-15 scaffolds in vitro and in vivo.

Materials and Methods

HDPSCs and HBMSCs were cultured as monolayers in basal or osteogenic media for 3 weeks. Osteogenic differentiation was confirmed using alkaline phosphatase (ALP) staining and ALP specific activity (ALPSA). In addition, the presence and distribution of osteogenic markers including Type 1 collagen, bone sialoprotein (BSP), osteopontin (OPN) and osteocalcin (OCN) was determined by immunohistochemisty. Gene expression for COL1, RUNX2 and OCN was determined using RT-PCR after 1, 3 and 5 weeks in basal culture. For 3D culture, HDPSCs were seeded on ABM scaffolds ± P-15 (CeraPedics LLC) and cultured in basal media for 6 weeks. Cell viability and growth were visualized by confocal and scanning electron microscopy. Osteogenic differentiation was confirmed by ALP staining and ALPSA. For in vivo studies, HDPSCs were injected and sealed in diffusion chambers containing ABM-P-15 or ABM alone which were then implanted intraperitoneally in nude mice for 8 weeks. The retrieved samples were then processed for histology.


J.F. Baker P. Walsh K.J. Mulhall

Introduction

Local anaesthetic has been reported to have a potentially detrimental effect on human chondrocytes both in vitro and in vivo. Due to chondroproliferative effects, magnesium may be an alternative intra-articular analgesic agent following arthroscopy. We aimed to examine the dose response effect of commonly used local anaesthetics on chondrocyte viability and also to report on the effect of adding magnesium to the local anesthetic agent.

Methods

Human chondrocytes were grown under standard culture conditions. Cells were exposed to either lignocaine (0.5, 1, 2%), levobupivacaine (0.125, 0.25, 0.5%), bupivacaine (0.125, 0.25, 0.5%) or ropivacaine (0.1875, 0.375, 0.75%) for 15 minutes. Cells were also exposed to a local anesthetic agent with the addition of magnesium (10, 20, or 50%). Cells exposed to culture media or saline served as controls. The MTS assay was used to assess cell viability 24 hours after exposure. One-way ANOVA were used to test for statistical significance.


M. Griffin A. Sebastian A. Bayat

Delayed facture repair and bony non-unions pose a clinical challenge. Understandably, novel methods to enhance bone healing have been studied by researchers worldwide. Electrical stimulation (ES) has shown to be effective in enhancing bone healing, however the best wave form and mechanism by which it stimulates osteoblasts remains unknown. Interestingly, it is considered that osteoblast activity depends on specific waveforms applied. Therefore, the aim of this study was to evaluate whether particular waveforms have a differential effect on osteoblast activity.

An osteoblast cell line was electrically stimulated with either capacitive coupling (CC) or a novel degenerate wave (DW) using a unique in vitro ES system. Following application of both waveforms, the extent of cytotoxicity, proliferation, differentiation and mineralisation of the osteoblasts were assessed using various assays. Differentiation and mineralisation were further analysed using quantitative real-time PCR (qRT PCR) and immunocytochemistry (ICC).

DW stimulation significantly enhanced the differentiation of the osteoblasts compared to CC stimulation, with increased protein and gene expression of alkaline phosphatase and type 1 collagen at 28 hours (p < 0.01). DW significantly enhanced the mineralisation of the osteoblasts compared to CC with greater Alizarin Red S staining and gene expression of osteocalcin, osteonectin, osteopontin and bone sialoprotein at 28 hours (p < 0.05). Moreover, immunocytochemical assays showed higher osteocalcin expression after DW stimulation compared to CC at 28 hours.

In conclusion

we have shown that ES waveforms enhanced osteoblast activity to different extent but importantly demonstrate for the first time that DW stimulation has a greater effect on differentiation and mineralisation of osteoblasts than CC stimulation. DW stimulation has potential to provide a secure, controlled and effective application for bone healing. These findings have significant implications in the clinical management of fracture repair and bone

non-unions.


D.F Hamilton P Gaston A.H.R.W Simpson

Introduction

Recovery of muscle strength following Total Knee Replacement (TKR) is variable, and can affect the resultant function of the patient. Satellite cells are undifferentiated myogenic precursors considered to be muscle stem cells that lie quiescently around the muscle fibre. These cells repair damaged fibres and have the potential to generate new muscle fibres. Therefore, theoretically, they could be associated with the variation in muscle recovery following surgery. We hypothesised that the recovery of muscle strength following knee replacement in a given patient would be influenced by the underlying number of satellite cells in that patient.

Methods

20 patients undergoing TKR were recruited from the waiting list of a single consultant. A muscle biopsy was taken at the time of surgery from the distal quadriceps. This was fixed in paraffin wax, and sections obtained. Satellite cells were identified with a primary mouse antibody for Pax7 - a cytoplasmic protein marker - and an immunofluorescent goat anti-mouse secondary. Slides were counterstained with DAPI to stain the myonuclei. The positive staining index (PSI) was calculated (number of satellite cells/total number of myonuclei x 100). Recovery of muscle (quadriceps) strength was assessed using the leg extensor power-rig (LegRig) pre-operatively, at 6 and 26 weeks post-operatively. Statistical analysis was performed using the Minitab version 15 software, the level of significance was set as p = 0.05.


A. Sharma F. Meyer M. Hyvonen S.M. Best N. Rushton R.E. Cameron

Introduction

The annual incidence of fractures in the UK is almost 4%. Bone grafting procedures and segmental bone transport have been employed for bone tissue regeneration. However, their limited availability, donor site morbidity and increased cost mean that there is still a large requirement for alternative methods and there is considerable research into regeneration using bone morphogenetic proteins (BMPs). The aims of this study are to synthesise and combine BMP-2 with a novel nanocomposite and study its release.

Materials and Methods

BMP-2 was synthesised using an E. coli expression system and purified. C2C12 cells were used to test its bioactivity using an alkaline phosphatase (ALP) assay. The modified solution evaporation method was used to fabricate 30% a-TCP/PLGA nanocomposite and it was characterized using SEM, TEM, TGA, XRD, EDX and particle size analysis. The release pattern of adsorbed BMP-2 was studied using an ELISA assay.


NJ. Bottomley MK. Javaid HS. Gill CAF. Dodd DW. Murray DJ. Beard AJ. Price

Introduction

Anteromedial gonarthrosis is a common well described pattern of knee osteoarthritis with cartilage wear beginning in the anteromedial quadrant of the medial tibial plateau in the presence of an intact and functioning ACL. It is well known that mechanical factors such as limb alignment and meniscal integrity affect the progression of arthritis and there is some evidence that the morphology of the tibial plateau may be a risk factor in the development of this disease. The extension facet angle is the angle of the downslope of the anterior portion of the medial tibial plateau joint surface in relation to the middle portion on a sagittal view. If this is an important factor in the development of AMG there may be potential for disease modifying intervention.

This study investigates if there is a significant difference in this angle as measured on MRI between a study cohort with early AMG (partial thickness cartilage damage and intact ACL) and a comparator control cohort of patients (no cartilage damage and ACL rupture).

Methods

3 Tesla MRI scans of 99 patients; 54 with partial thickness cartilage damage and 44 comparitors with no cartilage damage (acute ACL rupture) were assessed. The extension facet angle was measured (Osirix v3.6) using a validated technique on two consecutive MRI T2 sagittal slices orientated at the mid-coronal point of the medial femoral condyle. (InterClass Correlation 0.95, IntraClass Correlation 0.97, within subject variation of 1.1° and coefficient of variation 10.7%). The mean of the two extension angle values was used. The results were tabulated and analysed (R v2.9.1).


T Savaridas MS Gaston RJ Wallace DM Salter AHRW Simpson

Fractures repair by two mechanisms; direct fracture healing and indirect fracture healing via callus formation. Research concerning the effects of bisphosphonate on fracture repair has solely assessed indirect fracture healing. Patients with osteoporosis on bisphosphonates continue to sustain fragility fractures. A proportion of osteoporotic fractures require plate fixation. Bisphosphonates impair osteoclast activity and therefore, may adversely affect direct fracture healing that predominates with plate fixation.

Five skeletally mature Sprague-Dawley rats received daily subcutaneous injections of 1mg/kg Ibandronate (IBAN). Similarly, five control rats received saline (CONTROL). Three weeks following commencement of injections a tibial osteotomy was rigidly fixed with compression plating similar to that seen in routine clinical practice. Fracture healing was monitored with radiographs. Six weeks post plate fixation, animals were sacrificed. Radiographs were performed of the extricated tibiae following plate removal. The visibility of the osteotomy site was scored as totally visible, partially visible or absent as previously described. Mechanical testing was conducted on the healing osteotomies via 4-point bending.

Fractures healed without visible external callus. In the IBAN group three animals had totally visible osteotomy lines and two had partially visible osteotomy lines. The CONTROL group had three animals with absent osteotomy lines and two with partially visible osteotomy lines. The mean (±SD) stress at failure for the healing tibial osteotomies at 6 weeks was 28.8 (±23.97)MPa in the IBAN group and 37.4(±29.20) MPa in the CONTROL group (p=0.62)

Our results indicate that Ibandronate adversely affected direct fracture repair as demonstrated by the radiographic density of the fracture line. The strength of the repair was reduced but this did not reach statistical significance. Our results suggest that a sample size of 220 animals is required to detect a 15% difference (alpha 0.05, beta 0.2) which suggests the effect of bisphosphonates on direct fracture repair may be small.


A.M.H. Jones A Aarvold AM New D.G. Dunlop R.O.C. Oreffo

AIM

Avascular necrosis (AVN) of the femoral head is a potentially debilitating disease of the hip in young adults. Impaction bone grafting (IBG) of morcellised fresh frozen allograft is used in a number of orthopaedic conditions. This study has examined the potential of skeletal stem cells (SSC) to augment the mechanical properties of impacted bone graft and we translate these findings into clinical practice.

STUDY DESIGN

We have examined the effect of SSC density on augmentation of bone formation. An in vitro model was developed to replicate the surgical IBG process. Plain allograft was used as the control, and the SSC's seeded at a density of 5×103, 5×104 and 2×105 cells per cc of allograft for the experimental groups. All samples were cultured for 2 weeks and mechanically tested to determine shear strength using the Mohr Coulomb failure curve. The approach was translated to 3 patients with early avascular necrosis (AVN) of the femoral head. The patient's bone marrow was concentrated in theatre using a centrifugation device and the concentrated fraction of SSC's were seeded onto milled allograft. The patient's necrotic bone was drilled, curetted and replaced with impacted allograft seeded with SSC's. Osteogenic potential of concentrated and unconcentrated marrow was simultaneously compared in vitro by colony forming unit assays.


P Magill PM Walsh T Murphy KJ Mulhall

Introduction

Ischaemic preconditioning (IPC) is a phenomenon whereby a tissue is more tolerant to an insult if it is first subjected to short bursts of sublethal ischaemia and reperfusion. The potential of this powerful mechanism has been realised in many branches of medicine where there is an abundance of ongoing research. However, there has been a notable lack of development of the concept in Orthopaedic surgery. The routine use of tourniquet-controlled limb surgery and traumatic soft tissue damage are just two examples of where IPC could be utilised to beneficial effect in Orthopaedic surgery.

Methods

We conducted a randomized controlled clinical trial looking at the role of a delayed remote IPC stimulus on a cohort of patients undergoing a total knee arthroplasty (TKA). We measured the effect of IPC by analysing gene expression in skeletal muscle samples from these patients. Specifically we looked at the expression of Heat shock protein-90 (HSP-90), Catalase and Cyclo-oxygenase-2 (COX-2) at the start of surgery and at one hour into surgery. Gene analysis was performed using real time polymerase chain reaction amplification. As a second arm to the project we developed an in-vitro model of IPC using a human skeletal muscle cell line. A model was developed, tested and subsequently used to produce a simulated IPC stimulus prior to a simulated ischaemia-reperfusion (IR) injury. The effect of this on cell viability was investigated using crystal violet staining.


James Masters Ann Sandison Tim Diss Ferdinand Lali John Skinner Alister Hart

Metal-on-metal (MOM) hip resurfacings release chromium and cobalt wear debris into the surrounding joint. The hip tissue taken from failed MOM hips shows specific histological features including a subsurface band-like infiltrate of macrophages with particulate inclusions, perivascular lymphocytic infiltrate and fibrin exudation. This tissue response has been called Aseptic Lymphocytic Vasculitis Associated Lesion (ALVAL).

There is a recognised carcinogenic potential associated with hexavalent chromium and epidemiological data from first generation MOM arthroplasties may suggest an increased incidence of haematological malignancy. The ALVAL type reaction includes a marked proliferation of lymphocytes in the perivascular space and thorough investigation of this lymphocytic response is warranted.

This study aims to further characterise the lymphocytic infiltrate using immunohistochemistry and to test clonality using polymerase chain reaction (PCR).

Tissues from revised all cause failed MOM hip arthroplasties (n=77) were collected and analysed initially using routine H&E staining. Those that met the diagnostic criteria of ALVAL described above (n=34) were further stained with a panel of immunohistochemical markers (CD3, CD4, CD8 (T-cell markers) and CD20 (B-cell marker)). 10 representative ALVAL cases were selected and sent for gene rearrangement studies using PCR to determine whether the lymphocytes were polyclonal or monoclonal in nature.

The analysis of the lymphocytic aggregates in ALVAL, showed a mixed population of B and T cells. Within the aggregates, there was a predominance of B cells (CD20) over T cells (CD3). Of the 10 cases which were analysed by PCR, 7 were suitable for interpretation. None of these cases showed evidence of monoclonal lymphocyte proliferation.

The carcinogenic potential of wear debris from MOM hips, particularly affecting the haematopoietic system should be investigated. This study has shown a predominantly B-lymphocyte response in tissues surrounding MOM hips which is polyclonal. Although the numbers are small, the study suggests an immune mediated response in MOM hip tissue and excludes a neoplastic proliferation.

However, long term follow up of patients with MOM hips may be prudent.


H Zou S Brookes SP Lyngstadaas A Boccaccini E Tsiridis B Seedhom X Yang

Objective

Human bone marrow stromal cells (HBMSCs) are multipotent and can form bone, cartilage or other tissues under different inductive conditions. The aim of this study was to investigate the effects of enamel matrix derivative (EMD) on the growth and osteogenic differentiation of HBMSCs.

Methods

HBMSCs were cultured in monolayer with EMD (1, 10, 50,100, 250μg/ml) in aMEM supplemented with 2% FBS for 3 days. Cells cultured in aMEM supplemented with 2% FBS (basal medium) served as the control group. Double-stranded DNA was quantified by PicoGreen assay. Quantitative RT-PCR was performed to determine the expression levels of RUNX2, osteopontin (OPN) and osteocalcin (OCN), dentin matrix protein1 (DMP1) and dentin sialophosphoprotein (DSPP) at different time points (day 0, 5 and 10) when exposed to 10μg/ml EMD or basal medium. Alkaline phosphatase specific activity (ALPSA) was determined after 5 and 10 days culture. Mineral deposition (as calcium) was visualised using Alizarin Red staining.


A. Harrison V. Kobla J. Sandy J. Li A. Plaas

Background

Osteoarthritis (OA), is characterised with a loss of cartilage and pain in affected joints. It is this pain which most patients associate with their condition. Intra-articular (IA) hyaluronan (HA) has been shown to reduce the pain associated with OA both in animal models and in clinical trials. There are purified HA available and in recent years hyaluronan hydrogels, where the material has been cross-linked into networks, have become available. One of these cross-linked HA hydrogels is Durolane¯. This study has sought to evaluate the effect of Durolane in an in vivo model of osteoarthritis.

Methods

Mice (C57BL/6, 12 weeks) were obtained from Jackson Labs and all protocols were approved by Rush IACUC. Joint injury was initiated by TGFb1 injection as described [1]. Mice were given IA injections of 200 ng TGFb1, at days 1 and 3 delivered in a 6 ul volume into the rear right knee joint only. Twenty four hours after the second injection of TGFb1 10 ul of Durolane was injected into the same knee joint. All animals were exercised daily on a treadmill to induce tissue degeneration. Three groups of animals were evaluated: Naïve (n = 4), TGFb1 + saline (n = 5) and TGFb1 + Durolane (n = 5). Running performance was monitored daily and 15 days post injections, gait was assessed quantitatively using the TreadScan gait analysis system (CleverSys).


C. Findlay SS. Jameson S. Marshall B. Walker C. Walker RD. Meek A. Nicol

Background

Following an anterior cruciate ligament (ACL) injury, the affected knee is known to experience bone loss and is at significant risk of becoming osteoporotic. Surgical reconstruction is performed to attempt to restore the function of the knee and theoretically restore this bone density loss. Cross-sectional analysis of the proximal tibia using peripheral quantitative computed tomography (pQCT) enables localised analysis of bone mineral density (BMD) changes. The aim of this study was to establish the pattern of bone density changes in the tibia pre- and post- ACL reconstruction using pQCT image analysis.

Methods

Eight patients who underwent ACL reconstruction were included. A cross sectional analysis of the proximal tibia was performed using a pQCT scanner pre-operatively and one to two years post-operatively on both the injured and contralateral (control) knee. The proximal two and three percent slices [S2 and S3] along the tibia were acquired. These were exported to Matlab(tm) and automated segmentation was performed to remove the tibia from its surrounding structures. Cross correlation was applied to co-register pairs of images and patterns of change in BMD were mapped using a t-test (p<0.05). Connected components of pixels with significant change in BMD were created and used to assess the impact of ACL injury & reconstruction on the proximal tibial BMD.


P Jemmett HC Roberts S Paisey C Wilson DJ Mason

Meniscal tears commonly occur after a traumatic twisting injury to the knee (acute) or can form over time (degenerate). Symptoms include pain, swelling, and ‘locking’ of the knee. These symptoms are also commonly associated with osteoarthritis (OA). In some cases of OA, degenerative meniscal tears can also be present making it difficult to determine the cause of symptoms. Furthermore, acute meniscal lesions may be associated with early stage OA but often no radiological signs are evident. Many metabolites associated with joint disorders are released into the synovial fluid providing a real-time snap shot of joint pathology. The ability to examine concentrations of specific metabolites within synovial fluid could provide invaluable clinical information about the cause and stage of joint pathology. We have tested the hypothesis that ‘high resolution 1H-NMR can discriminate between osteoarthritic and meniscal tear-related metabolites within human synovial fluids and aid in clinical diagnosis.’

Method

Synovial fluid samples have been obtained during arthroscopy or knee replacement from patients with varying degrees of joint pathology (cartilage graded 0-4; meniscal tears classified as acute or degenerative). Samples were also taken from patients undergoing Anterior Cruciate Ligament (ACL) reconstruction with no additional pathology. Samples were analysed using 500 MHz 1H NMR spectroscopy. Chemical shifts were referenced to known concentration NMR internal standard (TSP), peaks identified by reference to published synovial fluid NMR spectra (1) and peak integrals measured using the Bruker software Topspin 2.0.

Results

Spectroscopy revealed a number of differences in metabolites between OA, meniscal tear and ACL pathologies. These included significantly increased concentrations of glutamate, n-acetyl glycoprotein and β-hydroxybutyrate in OA (n=10) and acute meniscal tears (n=6) compared to ACL samples (p<0.05, T-test, n=6). Specific metabolites were also able to discriminate between OA with no meniscal tear and OA with meniscal tear synovial fluids. For example, concentrations of n-acetyl glycoproteins, glutamate and CH3 lipids were significantly increased in OA without tears (n=10) compared to OA plus meniscal tears (n=12); conversely ceramide concentrations were significantly increased in OA plus tears compared to OA only samples (p<0.05, T-test).


I. McNamara M. Ong A. Rayment R. Brooks T. Prevost S. Best N. Rushton

Problems associated with allograft are well known. The addition of hydroxyapatite (HA) to allograft has various mechanical advantages, especially within revision arthroplasty. The mixing of bone and HA results in mechanical properties different from the individual parts. However, at present the changes in material properties the mix have not been fully investigated and the optimum mixing ratio not characterized. A compressive uniaxial chamber was used to investigate the change in mechanical properties occurring with the addition of HA in varying proportions to morcellised bone graft (MBG).

Materials and methods

MBG was prepared using femoral heads donated from patients undergoing total hip replacement surgery using a bone mill in a standard manner. Non porous HA (npHA) was prepared using a precipitation method of Calcium Carbonate and Orthophosphoric acid. The porous HA, (pHA) is a 60% macroporosity HA commercially prepared.

Chamber

The uniaxial compression chamber was a 30mm diameter, steel chamber. Holes were drilled to allow fluid drainage. Loads were applied using a 10 kN load cell. Specimens were prepared in the volumetric proportions pure HA, pure MBG, 2:1, 1:1, 1:2 ratio of MBG to HA. The samples were subjected to compressive forces of incrementally increasing loads of up to 2 KN for 60 cycles. The sample was then allowed to creep under a stress of 2 kN. MBG was also tested up to forces of 7 kN. The mechanical parameters that were examined were the stiffness of the sample at the 60th cycle, (Ec60), and creep


L Glen B Scammell W Ashraf R Bayston

Background

Deep infection rates of 1 - 2% following primary hip and knee arthroplasty are mainly due to endogenous contamination of the surgical site from bacteria within the patient's own skin. However surgical skin preparation removes only bacteria from the surface of the skin, leaving viable bacteria in the deeper layers of the skin within hair follicles and sweat and sebaceous glands. The aim of our study was to test the hypothesis that surface skin swabs taken after skin preparation with alcoholic povidone iodine would not grow bacteria, whereas full thickness biopsies taken from the line of surgical incision would grow bacteria.

Methods

Under LREC approval, informed consent was obtained from 22 patients undergoing primary hip (n=9) or knee (n=13) arthroplasty. All patients received intravenous antibiotic prophylaxis at the time of induction of anaesthesia. After surgical skin preparation with alcoholic povidone iodine, a surface skin swab and full thickness skin biopsy, using an 8mm x 4 mm elliptical punch, were taken. The swab culture was incubated aerobically and anaerobically at 37°C. The skin biopsy was cut aseptically in half. One half was crushed using artery forceps, placed in 5mL anaerobe basal broth and incubated anaerobically at 37°C. The other half of the skin biopsy was frozen in isopentane and gram – stained after sectioning.


G. Cox PV. Giannoudis S. Boxall C. Buckley E. Jones D. McGonagle

Introduction

Iliac crest bone marrow aspirate (ICBMA) is frequently cited as the ‘gold-standard’ source of MSCs. MSCs have been shown to reside within the intramedullary (IM) cavities of long-bones [Nelea, 2005] however a comparative assessment with ICBMA has not yet been performed and the phenotype of the latter compartment MSCs remains undefined in their native environment.

Methods

Aspiration of the IM cavities of 6 patients' femurs with matched ICBMA was performed. The long-bone-fatty-bone-marrow (LBFBM) was filtered (70μm) to separate liquid and solid fractions and the solid fraction was briefly (60min, 37oC) digested with collagenase. MSC enumeration was performed using the colony-forming-unit-fibroblast (CFU-F) assay and quantification of cells with the CD45low CD271+ phenotype by flow-cytometry. [Jones 2002, Buhring 2007] MSCs were cultured and standard expansion media and passage 2 cells were differentiated towards osteogenic, adipogenic and chondrogenic lineages.


J.L. Boyd A.B. Zavatsky H.S. Gill

Background

Osteoarthritis (OA) is a degenerative, chronic disease of the articular cartilage that affects more than 150 million people [1]. In the knee, OA can begin as either isolated medial OA or isolated lateral OA. Previous research [2,3] shows medial OA and lateral OA have characteristic cartilage lesion locations and progression patterns as well as flexion angles associated with lesion development, indicating strong involvement of mechanical factors in disease initiation. Therefore, it is important to investigate these mechanical factors. Previous studies combined data sets (geometry, motion, load) from separate sources. The aim of the current work was to use a consistent multi-modal approach.

Method

A finite element (FE) model of a healthy knee in full extension was created using magnetic resonance imaging (MRI) and motion analysis data from the same subject (female, 24 yrs). MRI data was obtained using a 3T MRI scanner (Philips Medical Systems/Achieva). Surface geometries of the tibia, femur, and associated cartilage were then semi-automatically segmented and processed (Mimics 12.5; Geomagic Studio 11; SolidWorks 2009). Motion data was collected at 100 Hz (Vicon 612) during level walking and subsequently applied to a lower limb model (AnyBody Version 3.0) to calculate muscle forces. Both sets of data were then combined to create a subject-specific FE model (ANSYS 11.0) which was solved to determine relative contact areas, pressures, and deformations in the medial and lateral tibiofemoral compartments.


R S Kotwal K Brakspear H Roberts C Wilson R Williams J Sultan D J Mason

Glutamate is a neurotransmitter that transmits mechanical signals in bone (1) and activates glutamate receptors and transporters, in bone, cartilage, meniscus and synovium (2). Glutamate receptor activation influences inflammatory, degenerative and nociceptive pathways in arthritic joints (2). Thus glutamate signalling is a mechanism whereby mechanical load can directly influence joint pathology and pain. We have investigated components of glutamate signalling in the subchondral bone of patients with osteoarthritis to determine which are expressed and whether this varies in anatomical regions subject to different loads. Subchondral bone was sampled from tibial cuts derived from total knee arthroplasty (n=2, TKR, Kellgren Lawrence grade 3) and from tibial drill hole sites from high tibial osteotomy (n=5, HTO, KL grades 2 and 3) for osteoarthritis. RNA was extracted, reverse transcribed and RT-PCR performed for a housekeeping gene GAPDH, a glutamate transporters (EAAT-1, EAAT1ex9skip), glutamate receptors (NR2A and KA1), a bone matrix protein, osteocalcin, and signaling molecules (osteoprotegerin [OPG], RANKL). We found differential mRNA expression in different regions of subchondral bone. In one TKR patient, EAAT-1 expression was significantly reduced in the anterior zone versus the middle or posterior zones of the tibial plateau (ANOVA, p<0.001). HTO bone cores were subdivided medial/lateral and anterior/posterior. Good quality RNA was obtained from bone cores removed from drill holes during HTO surgery, with GAPDH, osteocalcin, EAAT-1, EAAT1ex9skip, NR2A, KA1, OPG and RANKL mRNA expression detected. In one patient, comparison of gene expression in bone cores obtained pre and post HTO revealed that EAAT1ex9skip was rarely detected in post-op bone whereas KA1 was rare in pre-op bone. This differential mRNA expression may be due to the altered loading through the joint caused by the osteotomy, although these on/off differences need to be quantified to confirm this.

We have shown that glutamate transporters and receptors are expressed in human subchondral bone. Activation of these receptors and transporters by the increased synovial fluid concentrations of glutamate released in arthritis will influence pathological changes and nociception. In some patients, glutamate transporter mRNA expression appears to vary with anatomical location in bone, or after HTO surgery, consistent with our original discovery of this transporter as mechanically-regulated in bone (1). If glutamatergic signaling is mechanically regulated in the human knee, this will vary during arthritic disease progression and after joint realignment, providing a direct mechanism linking mechanical loading through the joint to pathology and pain in arthritis.


T. Savaridas R.J. Wallace S.P. Dawson A.H.R.W. Simpson

The effect of bisphosphonates on the mechanical properties of the uninjured contra-lateral cortical bone during fracture healing is poorly reported. There remains conflicting evidence with regards the effect of bisphosphonate therapy on cortical bone strength. We assessed the effect of nine weeks of Ibandronate therapy, in a dose known to preserve cancellous bone BMD and strength, on the mechanical properties of the uninjured rat tibial diaphyses using a standardised model of tibial osteotomy and plate fixation. Skeletally mature ex-breeder rats were used. Stress at failure of the tibial diaphyses was measured by a four-point bending test using a custom made jig for rat tibiae. The mechanical strength was compared with radiographic measurements of bone density. Animals received daily subcutaneous injections. 11 rats received 1μg/kg Ibandronate (IBAN) daily and 17 rats received 1ml 0.9% Sodium Chloride (CONTROL) daily.

The IBAN group had a statistically significant, p=0.024, higher stress at failure 212.7 (±42.04) MPa compared to the CONTROL group 171.7 (±46.13)MPa. There was a positive correlation between the mechanical strength of bone and the radiological measure of bone density.

Osteopenia is known to occur following a fracture even in the contra-lateral limb. This study demonstrates that ibandronate therapy has no detrimental effect and may even increase the strength of uninjured cortical bone during the fracture healing process. The longer term effect of ibandronate on cortical bone especially in relation to the accumulation of mico-damage requires further study. Bisphosphonate effect on the uninjured limb needs to be considered when reporting proportional strength of fracture repair compared to the uninjured limb.


Arul Ramasamy Adam M Hill Ian Gibb Spyros D Masouros Anthony MJ Bull Jon C Clasper

Introduction

Civilian fractures have been extensively studied with in an attempt to develop classification systems, which guide optimal fracture management, predict outcome or facilitate communication. More recently, biomechanical analyses have been applied in order to suggest mechanism of injury after the traumatic insult, and predict injuries as a result of a mechanism of injury, with particular application to the field so forensics. However, little work has been carried out on military fractures, and the application of civilian fracture classification systems are fraught with error. Explosive injuries have been sub-divided into primary, secondary and tertiary effects. The aim of this study was to 1. determine which effects of the explosion are responsible for combat casualty extremity bone injury in 2 distinct environments; a) in the open and b) enclosed space (either in vehicle or in cover) 2. determine whether patterns of combat casualty bone injury differed between environments Invariably, this has implications for injury classification and the development of appropriate mitigation strategies.

Method

All ED records, case notes, and radiographs of patients admitted to the British military hospital in Afghanistan were reviewed over a 6 month period Apr 08-Sept 08 to identify any fracture caused by an explosive mechanism. Paediatric cases were excluded from the analysis. All radiographs were independently reviewed by a Radiologist, a team of Military Orthopaedic Surgeons and a team of academic Biomechanists, in order to determine the fracture classification and predict the mechanism of injury. Early in the study it became clear that due to the complexity of some of the injuries it was inappropriate to consider bones separately and the term ‘Zone of Insult’ (ZoI) was developed to identify separate areas of injury.


W.G.P. Eardley J. Clasper M. Midwinter S.A. Watts

Crown copyright 2009. Published with the (permission of the Defence Science and Technology Laboratory on behalf of the Controller of HMSO

Introduction

The optimum strategy for the care of war wounds is yet to be established. A need exists to model complex extremity injury, allowing investigation of wound management options.

Aim

To develop a model of militarily relevant extremity wounding.


A. Metcalfe C. Stewart N. Postans A. Dodds H. Smith C. Holt A. Roberts

Introduction

Patients with knee osteoarthritis (OA) often tell us that they put extra load on the joints of the opposite leg as they walk. Multiple joint OA is common and has previously been related to gait changes due to hip OA (Shakoor et al 2002). The aim of this study was to determine whether patients with medial compartment knee OA have abnormal biomechanics of the unaffected knee and both hips during normal level gait.

Methods

Twenty patients (11 male, 9 female), with severe medial compartment knee OA and no other joint pain were recruited. The control group comprised 20 adults without musculoskeletal pain. Patients were reviewed, x-rays were examined and WOMAC and Oxford knee scores were completed. A 12 camera Vicon (Vicon, Oxford) system was used to collect kinematic data (100Hz) on level walking and the ground reaction force was recorded using three AMTI force plates (1000Hz). Surface electrodes were placed over medial and lateral quadriceps and hamstrings bilaterally to record EMG data (1000Hz). Kinematics and kinetics were calculated using the Vicon ‘plug-in-gait’ model. A co-contraction index was calculated for the EMG signals on each side of the knee, representing the magnitude of the combined readings relative to their maximum contraction during the gait cycle. Statistical comparisons were performed using t-tests with Bonferroni's correction for two variables and ANOVA for more than two variables (SPSS v16).


S Chaudhury C Holland D Porter F Vollrath A J Carr

Background

High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA).

Methods

The shear properties of four RCT repair grafts were measured (Restore, GraftJacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G') as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations.

A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn's multiple comparison test.


G.M. Whatling C. Wilson C.A. Holt

INTRODUCTION

Motion analysis is routinely used in the clinical and research sectors to quantify joint biomechanics. It plays an important role in clinical assessments by aiding the physician to distinguish between primary movement abnormalities and any secondary compensatory mechanisms that may overshadow the cause of the problem. During a data collection session, a wealth of biomechanical data regarding joint and segment kinematics and kinetics are collected from patients performing daily activities. Objective classification can be used to automate a diagnosis from this data and has been used previously to analyse measurements of level gait [1]. It is of interest to assess the knee during stair-gait as this activity involves greater range of motion (ROM) of the lower limbs, larger forces and moments acting at the knee.

AIM

The aim of the current study is to explore the use of an objective classifier [1] to characterise knee osteoarthritis (OA) and monitor functional recovery following a total knee replacement (TKR) using measurements from stair-gait.


G. M. Whatling C. Wilson C. A. Holt

INTRODUCTION

Useful feedback from a Total Knee Replacement (TKR) can be obtained from post-surgery in-vivo assessments. Dynamic Fluoroscopy and 3D model registration using the method of Banks and Hodge (1996) [1] can be used to measure TKR kinematics to within 1° of rotation and 0.5mm of translation, determine tibio-femoral contact locations and centre of rotation. This procedure also provides an accurate way of quantifying natural knee kinematics and involves registering 3D implant or bone models to a series of 2D fluoroscopic images of a dynamic movement.

AIM

The aim of this study was to implement a methodology employing the registration methods of Banks and Hodge (1996) [1] to assess the function of different TKR design types and gain a greater understanding of non-pathological (NP) knee biomechanics.


S Li VC Duance EJ Blain

Introduction

Low back pain is a major public health problem in our society. Degeneration of intervertebral disc (IVD) appears to be the leading cause of chronic low-back pain [1]. Mechanical stimulations including compressive and tensional forces are directly implicated in IVD degeneration. Several studies have implicated the cytoskeleton in mechanotransduction [2, 3], which is important for communication and transport between the cells and extracellular matrix (ECM). However, the potential roles of the cytoskeletal elements in the mechanotransduction pathways in IVD are largely unknown.

Methods

Outer annulus fibrosus (OAF) and nucleus pulposus (NP) cells from skeletally mature bovine IVD were either seeded onto Flexcell¯ type I collagen coated plates or seeded in 3% agarose gels, respectively. OAF cells were subjected to cyclic tensile strain (10%, 1Hz) and NP cells to cyclic compressive strain (10%, 1Hz) for 60 minutes. Post-loading, cells were processed for immunofluorescence microscopy and RNA extracted for quantitative PCR analysis.


A. Aziz B. Hemmes S. Khalid HMJ. Janzing B. Meesters PRG. Brink

Introduction

The treatment of distal femoral fractures has undergone several changes during the past century, from non-operative techniques to more recently minimally-invasive internal fixation. The Less Invasive Stabilisation System (LISS) is an internal fixation plate that combines closed fixation of the distal femur using an anatomically pre-contoured plate with locked unicortical screws.

Study aim

The purpose of this multicentre study was to review the use of the LISS plate in three regional centres with respect to fracture healing between different severities of fractures.


NJ. Bottomley E. McNally L. Jones MK. Javaid N. Arden HS. Gill CAF. Dodd DW. Murray DJ. Beard AJ. Price

Introduction

Anteromedial osteoarthritis of the knee (anteromedial gonarthrosis-AMG) is a common form of knee arthritis. In a clinical setting, knee arthritis has always been assessed by plain radiography in conjunction with pain and function assessments. Whilst this is useful for surgical decision making in bone on bone arthritis, plain radiography gives no insight to the earlier stages of disease. In a recent study 82% of patients with painful arthritis had only partial thickness joint space loss on plain radiography. These patients are managed with various surgical treatments; injection, arthroscopy, osteotomy and arthroplasty with varying results. We believe these varying results are in part due to these patients being at different stages of disease, which will respond differently to different treatments. However radiography cannot delineate these stages. We describe the Magnetic Resonance Imaging (MRI) findings of this partial thickness AMG as a way of understanding these earlier stages of the disease.

Method

46 subjects with symptomatic partial thickness AMG underwent MRI assessment with dedicated 3 Tesla sequences. All joint compartments were scored for both partial and full thickness cartilage lesions, osteophytes and bone marrow lesions (BML). Both menisci were assessed for extrusion and tear. Anterior cruciate ligament (ACL) integrity was also assessed. Osteophytes were graded on a four point scale in the intercondylar notch and the lateral margins of the joint compartments. Scoring was performed by a consultant radiologist and clinical research fellow using a validated MRI atlas with consensus reached for disagreements. The results were tabulated and relationships of the interval data assessed with linear by linear Chi2 test and Pearson's Correlation.


I. McNamara A. Rayment S. Best N. Rushton

In vitro femoral studies have demonstrated the addition of hydroxyapatite (HA), to morcellised bone graft (MBG) decreases femoral prosthesis subsidence. However, with an increased risk of femoral fracture during the impaction of a MBG:HA mixture, possibly due to greater force transmission to the femoral cortex via the HA. The aim was to compare the hoop strains and subsidence of a 1:1 mixture of MBG:HA with pure bone allograft during impaction and subsequent endurance testing in a revision hip arthroplasty model.

Materials and methods Large Sawbone femurs were prepared to represent a femur with bone loss (Sawbones, Sweden). 12 uniaxial strain gauges were attached to each femur at 0, 90, 180 and 270 degrees, at distal, midshaft, proximal points to measure hoop strain. Impaction grafting was performed using X-Change 2 instruments and an Instron servohydaulic machine for 2 distal impactions and 4 proximal impactions for 60 impactions each.

Study groups

The study consisted of four experimental groups: 1)Pure MBG, force of 1.98 kN 2)Pure MBG, force 3.63kN. 3)1:1 mixture of MBG: porous HA (pHA), 4)1:1 mixture MBG: non porous HA (npHA). 6 samples of each group were performed.

Endurance testing

The potted femur was loaded in a manner representing the walking cycle (1.98kN) at 1 Hz for 50 000 cycles. The displacement of the femoral head during loading was measured by two displacement transducers (LVDT) were mounted on aluminum brackets to measure vertical displacement and rotation.


J McLaren K Shakesheff R Quirk A Goodship R Bayston BE Scammell

Introduction

Open fractures occur with an annual incidence of 11.5 per 100,000 (6900 pa in UK). Infection rates, even with intravenous broad-spectrum antibiotics, remain as high as 22%. For this reason necessary bone grafting is usually delayed until soft-tissue cover of the bone injury is achieved. A biodegradable bone graft that released sustained high concentrations of antibiotics and encouraged osteogenesis, that could be implanted safely on the day of injury would reduce infection rates and avoid reoperation and secondary grafting. The non –union rate (approx 350 pa in UK) should also be reduced. Such a graft, consisting of a PLA/PGA co –polymer and containing antibiotics, is under development and here we report assessment of spectrum and duration of antimicrobial activity and effect of addition of antibiotics on mechanical properties.

Methods

Varying concentrations of gentamicin, colistin, clindamycin and trimethoprim, singly and in combination, were added to the copolymer and test pieces were made. These were then tested using an established method (SPTT) which determines degree and duration of antimicrobial activity as well as risk of emerging resistance. Test bacteria were Staphylococcus epidermidis, Staphylococcus aureus, MRSA and Escherichia coli. Mechanical properties (compressive strength and porosity) were determined using established methods.


R. J. Underwood P. M. Cann J. Skinner A. Hart

SUMMARY

The relationship between component position, wear rate and edge loading was investigated for 115 explanted current generation Metal-on-Metal (MoM) hips. Edge wear was detected in: 63% of all hips; and 48% of those with cups positioned within Lewinnek's box.

BACKGROUND

The link between steeply inclined cups (>55 degrees) and edge loading is known for all common hip bearing couples. Edge loading is associated with high rates of wear, and has been linked to premature failure of hips.


J. Davies S. Wilshaw D. Shaw E. Ingham Z. Jin J. Fisher

Introduction

Articular hyaline cartilage has a unique structural composition that allows it to endure high load, distribute load to bone and enables low friction movement in joints. A novel acellular xenogenic graft is proposed as a biological cartilage replacement, for repair of osteochondral defects. Acellular porcine cartilage has been produced using repeated freeze thaw cycles and washing using hypotonic buffers and sodium dodecyl sulphate solution (SDS; Keir, 2008). DNA content of the acellular matrix was reduced by 93.3% compared to native cartilage as measured by nanodrop spectrophotometry of extracted DNA, with a corresponding reduction in glycosaminoglycan (GAG) content.

Hypothesis

It was hypothesised that penetration of decellularisation solutions into the native tissue could be improved through deformation of the cartilage under confined compression and then allowing the osteochondral pin to recover in solution, allowing removal of cellular DNA and greater retention of the GAGs.


P.H.M. Péchon R. Pullin M.J. Eaton S.L. Evans

Introduction

Iatrogenic proximal femur hoop-stress fracture is a recognised complication of uncemented hip arthroplasty. It has a reported incidence of two to three percent and increases patient morbidity. We describe a novel technology that predicts fracture in real-time by less than one minute.

Method

Four proximal femora from red deer (Cervus elaphus), similar size to human proximal femora, were prepared to accept an uncemented hip arthroplasty femoral rasp (Finsbury Orthopaedics) and then mounted in a loading machine. The femora were fresh-frozen, defrosted and kept at room temperature in 0.9% saline swabs. The rasp was forced into each femur in repeated loading cycles every 10 seconds, in steps of 100N increasing from 200N to over 2000N until fracture, in a manner to simulate surgery. One sensor was attached to the surface of the proximal femur and one to the femoral rasp. The sensor outputs were recorded, analysed and displayed on a PC using a software algorithm to show signal energy (joules) and amplitude (decibels). The proximal femur was coated with specular marking paint to permit real-time 3-D digital image correlation (DIC) analysis. DIC is an established tool in engineering fracture analysis and utilises two spatially orientated video cameras to measure surface strain and fracture. The femur was observed by the human eye and loaded in cycles until a fracture was seen. The moment of fracture was marked in the recording timeline. DIC was used to confirm fracture.


Joseph Alsousou Li Larry Eugene McNally Alison Noble Keith Willett

Purpose

Functional ultrasound Elastography (FUSE) of Tendo Achilles is an ultrasound technique utilising controlled, measurable movement of the foot to non-invasively evaluate TA elastic and load-deformation properties. The study purpose is to assess Achilles tendons, paratenon and bursa mechanical properties in healthy volunteers and establish an outcome tool for TA treatment.

Methods

Forty asymptomatic Achilles tendons of 20 healthy volunteers were recruited (10 men and 10 women, age range 18-55). One patient with Acute Achilles rupture scanned to evaluate the tendon gap. Each volunteer answered the Foot and Ankle Outcome Score (FAOS) and Victorian Institute Sport Assessment score (VISA-A) questionnaires. The Achilles Tendons were divided into three thirds (total 120 Proximal, middle and distal thirds). Three longitudinal images of each third were obtained using portable US scan device (Z.one, Zonare Medical System Inc., USA, 8.5 MHz). Images processing was achieved using a MatLAb software (developed by the research team) in parallel Oxford university computers. Each 1/3rd Achilles tendon under went the following scans:

Free hand US scan

Free hand Compression decompression Elastography scan

Dorsal Flexion elastography

Planter flexion elastography

Zonare real-time Elastography

Elastography scan with the Oxford isometric dynamic foot and Ankle mover (OIDFA)

B mode and elasticity images were derived from the raw ultrasound radio frequency data. The anatomical structures mechanical properties were evaluated by a quantitative score of different colours representing stiff tissue (blue) to more soft tissue (green, yellow, red).


P. Hyde R. Vicars J. Fisher T. Brown R. M. Hall

Introduction

It is believed that wear of replacement joints vivo in is strongly dependent on input motions (kinematics) and loading. There is difficulty in accurately measuring total disc replacement (TDR) kinematics in vivo. It is therefore desirable to ascertain the sensitivity of implant wear in vitro to perturbations of the standard testing parameters. An anterior-posterior (AP) shear force input is not currently included in the present ISO and ASTM testing standards for lumbar TDRs but is known to exist in in vivo. Other joint-replacement wear tests have shown that the phasing of input motions influences the ‘cross-shear’ process of polyethylene wear. Polyethylene bearing materials do not behave linearly to axial loading changes and so the effect on wear rate is difficult to predict. The study aim was to assess the effects on wear of a ProDisc-L TDR under the following conditions: ISO 18191-1 standard inputs; an additional input AP shear; input kinematics phasing changes; axial loading changes.

Methods

A five active degree of freedom (DOF) spine simulator was used to compare the effects of varying the kinematic and loading input parameters on a ProDisc-L TDR (Synthes Spine). A four DOF standard ISO (ISO18192-1) test was followed by a five DOF test which included the AP shear force. The standard ISO test was repeated on a second simulator (of identical design) but with the phasing of the lateral bend (LB) and flexion extension (FE) motions changed to be in-phase, creating a low cross-shear motion pattern. The standard ISO test was then modified to give half the ISO standard axial loading. All tests conducted were based on the ISO18192-1 standard for lumbar implants with 15 g/l protein lubricant and modified as described. Gravimetric wear measurements were taken every million cycles (mc) in units of milligrams (mg). Six discs were tested to give statistically significant results.


S. J. Mellon Y-M. Kwon D. J. Simpson D. W. Murray H. S. Gill

Introduction

Metal-on-metal (MoM) hip resurfacing arthroplasty is a popular choice for young and active patients. However, there are concerns recently regarding soft tissue masses or pseudotumours. The appearance of these complications is thought to be related blood metal ion levels. The level of metal ions in blood is thought to be the result of MoM wear. In the present study the contribution of acetabulum orientation to stress distribution was investigated.

Methods

Four subjects with MoM resurfacings and with known blood metal ion levels underwent motion analysis followed by CT scans. The positions of the acetabular (cup) and femoral components were determined the CT data relative to local coordinate systems in the pelvis (PCS) and the femur (FCS). Transformations, calculated from the motion analysis data, between the PCS and FCS gave the position of the cup relative to the femoral component for each frame of captured motion data.

Hip reaction forces were taken from published data1. The intersection of hip reaction force with each subject's cup and the increase in inclination required to move the force to the edge of the cup was calculated for 2% intervals during the stance phase of gait. Finite element models representing each subject's cup and femoral components were created and contact stresses were determined for the native cup inclination angle. For each model, the effect of increasing the inclination of the cup, by up to 10°, in 1° increments, was determined.


D Pitt HI Roach

INTRODUCTION

Many patients suffering from osteoarthritis (OA) take daily glucosamine (GlcN) in the hope of slowing down disease progression and ameliorating pain. However, the physiological basis of this effect is not known. We previously presented preliminary data suggesting that GlcN prevented the increase in interleukin-1beta (IL-1b) expression caused by addition of inflammatory cytokines to cultures of healthy human articular chondrocytes. Previous studies had also shown that, in OA, epigenetic DNA methylation loss at specific CpG sites in relevant promoters ‘unsilences’ the genes and that this DNA de-methylation underlies the aberrant gene expression of proteases (Arthritis Rheum 52;3110-24). Furthermore, exogenous inflammatory cytokines have the capacity to cause DNA de-methylation in the IL-1b promoter (Arthritis Rheum. 2009, 60, 3303-3313). The aims of the present study were to investigate whether GlcN not only prevents the increased IL-1b expression, but also inhibits epigenetic unsilencing by preventing the cytokine-induced loss of DNA methylation.

METHODS

Healthy chondrocytes were isolated from the articular cartilage of four femoral heads, after operations following femoral neck fracture (ethic permission was obtained). The chondrocytes were cultured for 5 weeks in four treatment groups: no treatment (control); with IL-1b and oncostatin M (IL1b+OSM); with 2.0mM GlcN; and with IL1b+OSM+GlcN. Total RNA and genomic DNA were extracted. The % DNA methylation at the CpG site at -299bp (previously identifies as the crucial CpG site) was determined after bisulphite modification with a pyrosequencer. Gene expression of IL-1B was quantified by SybrGreen-based qRT-PCR.


P Magill J McGarry JM Queally SF Morris JP McElwain

Introduction

Acetabular fractures are a challenging problem. It has been published that outcome is dependent upon the type of fracture, the reduction of the fracture and concomitant injuries. The end-points of poor outcome include avascular necrosis of the femoral head, osteoarthritis. However, we lack definitive statistics and so counselling patients on prognosis could be improved. In order to achieve this, more outcome studies from tertiary referral centres are required. We present the first long term follow up from a large tertiary referral centre in Ireland.

Methods

We identified all patients who were ten years following open reduction and internal fixation of an acetbular fracture in our centre. We invited all of these patients to attend the hospital for clinical and radiographic follow-up. As part of this, three scoring systems were completed for each patient; the Short-form 36 health survey (SF36), the Merle d'Aubigné score and the Short Musculoskeletal Functional Assessment (SMFA).


Ahmad Ali Ghazzawi Len Nokes Carl Byrne

Introduction

Kager's fat pad (KFP) is located in Kager's triangle between the Achilles tendon (AT), the superior cortex of the calcaneus and Flexor Hallucis Longus (FHL) muscle & tendon. Although the biomechanical functions of KFP are not yet fully understood, a number of studies suggested that KFP performs important biomechanical roles including assisting in the dynamic lubrication of the AT subtendinous area, protection of AT vascular supply, and load and stress distribution within the retrocalcaneal bursa space. Similar to the knee meniscus, KFP has become under increasing investigations since strong indications were found that it serves more than just a space filler. Both KFP and the knee meniscus are anchored to their surrounding tissues via fibrous attachments, they can be found in encapsulated (or ‘air tight’) regions, lined by synovial membranes, and they both slide within their motion ranges. The protruding wedge (PW) of KFP was observed to slide in and out of the retrocalcaneal bursal space during ankle plantarflexion and dorsiflexion, respectively. In-vitro studies of KFP suggest that it reduces the load by 39%, which is similar to that of the knee meniscus (30%-70% of the load applied on the knee joint). This study investigated the in-vivo load bearing functionality of KFP.

Materials and Methods

The ankles of 5 volunteers (3 males, 2 females, Age 20-28, BMI 21-26) were scanned using a 0.2T MRI scanner at ankle plantarflexion and neutral positions. The ankles of 2 of those volunteers were later scanned using a 3T MRI scanner for higher accuracy. The areas and volumes of KFP were measured using Reconstruct¯ 3D modelling software. The hind foot of the volunteers were scanned using dynamic ultrasound to measure in-vivo real time shape changes of PW.


D. J. Simpson B. Kendrick G. Thomas H.S. Gill J.J. O'Connor D. W. Murray

Introduction

The results of the original mobile bearing Oxford unicompartmental knee replacement (UKR) in the lateral compartment have been disappointing because of high dislocation rates (11%). This original implant used a flat bearing articulation on the tibial tray. To address the issue of dislocation a new implant (domed tibia with biconcave bearing to increase entrapment) was introduced with a modified surgical technique. The aim of this study was to compare the risk of dislocation between a domed and flat lateral UKR.

Methods

Separate geometric computer models of an Oxford mobile bearing lateral UKR were generated for the two types of articulation between the tibial component and the meniscal bearing: Flat-on-flat (flat) and Concave-on-convex (domed). Each type of mobile bearing was used to investigate three distinct dislocation modes observed clinically: lateral to medial dislocation, with the bearing resting on the tray wall (L-M-Wall); medial to lateral dislocation, out of the joint space (M-L); anterior to posterior dislocation, out of the joint space (A-P).

A size C tray and a medium femoral component and bearing were used in all models. The femoral component, tibial tray and bearing were first aligned in a neutral position. For each dislocation the tibial tray was restrained in all degrees of freedom. The femoral component was restrained from moving in the anterior-posterior directions and in the medial-lateral directions. The femoral component was also restrained from rotating about the anterior-posterior, medial-lateral and superior-inferior directions. This meant that the femoral component was only able to move in the superior-inferior direction. Different bearing sizes were inserted into the model and the effect that moving the femoral component medially and laterally had on the amount of distraction required to cause bearing dislocation was investigated.


L. McGonagle M.D. Jones D. Dowson P King P.S. Theobald

Frictional resistance to tendon gliding is minimised by surrounding loose areolar tissues. During periods of prolonged immobilisation, for example post tendon-repair, adhesions can form between the two adjacent tissues, thereby limiting function. Whilst agents applied during surgery are recognised to succeed in adhesion prevention, they have also been reported to provide some reduction in friction during in vitro tendon-bony pulley investigations. This study investigated the effectiveness of common anti-adhesion agents in lubricating the tendon-surrounding tissue contact by comparison with a control study. By using a validated apparatus and with reference to the Stribeck curve, it was determined that the natural in vivo contact is likely to be lubricated by a film of synovial-like fluid. Application of all anti-adhesives generated a similarly efficient lubricating system, and hence administration of these agents should be encouraged to all regions of the tendon disrupted during surgery. Minimising frictional resistance to gliding will reduce the likelihood of tendon ‘gapping’ - and subsequently failure - at the repair site.


Toby O Smith Rachel Nichols Simon T Donell Caroline B Hing

Hip resurfacing procedures have gained increasing popularity for younger, higher demand patients with degenerative hip pathologies. However, with concerns regarding revision rates and possible adverse metal hypersensitivity reactions with metal-on-metal articulations, some authors have questioned the hypothesised superiority of hip resurfacing over total hip arthroplasty. The purpose of this meta-analysis was to compare the clinical and radiological outcomes and complication rates of these two procedures.

A systematic review was undertaken of all published and unpublished research up to January 2010. The primary search was of the databases Medline, CINAHL, AMED and EMBASE, searched via Ovid using MeSH terms and Boolian operators ‘hip’ AND ‘replacement’ OR ‘arthroplasty’ AND ‘resurfacing’. A secondary search of unpublished literature was conducted using the databases SIGLE, the National Technical Information Service, the National Research Register (UK), the British Library's Integrated Catalogue and Current Controlled Trials databases using the same search terms as the primary search. All included studies were critically appraised with the CASP appraisal tool.

In total, 46 studies were identified from 1124 citations. These included 3799 hip resurfacings and 3282 total hip arthroplasties. On meta-analysis, functional outcomes for subjects following hip resurfacing were better than or the same as subjects with a total hip arthroplasty, with significantly higher WOMAC score (Mean Difference (MD)=−2.41; 95% Confidence Interval (CI): −3.88, −0.94; p=0.001), and significantly better Harris Hip Score (range of motion component) (MD=−0.05; 95% CI: (−0.07, −0.03; p<0.0001) and overall Harris Hip Score (MD=2.51; 95% CI: 1.24, 3.77; p=0.0001) in the hip resurfacing compared to total hip arthroplasty cohorts. However, there were significantly greater incidences of heterotopic ossification (Risk Ratio (RR)=1.62; 95% CI: 1.23, 2.14; p=0.006), aseptic loosening (RR=3.07; 95% CI:1.11, 8.50;p=0.03) and revision surgery (RR=1.72; 95% CI: 1.20, 2.45; p=0.003) with hip resurfacing compared to total hip arthroplasty. The evidence-base presented with a number of methodological inadequacies such as the limited use of power calculations and poor or absent blinding of both patients and assessors, potentially giving rise to assessor bias. In respect to these factors, the current evidence-base, whilst substantial in its size, may be questioned in respect to its quality in determining superiority of hip resurfacing over total hip arthroplasty.


K.W. Chan J. Wong N.W. Thompson

INTRODUCTION

Intramedullary nail fixation has been used for successful treatment of long bone fracture such as humerus, tibia and femur. We look at the experience of our trauma unit in treating long bone fracture using the AO approved Expert femoral/tibial nail and proximal femoral nail antirotation (PFNA). We look at the union and complication rates in patients treated with AO approved nailing system for pertrochanteric, femoral and tibial shaft fracture.

METHODS

We carried out retrospective case notes review of patients that underwent femoral and tibial nailing during the period of study- October 2007 to August 2009. All patients were treated using the AO approved nailing system. We identified all trauma patients that underwent femoral and tibial nailing through the trauma register. Further information was then obtained by going through medical notes and reviewing all followed-up X-rays stored within the online radiology system.


W. Nishio Ayre S. L. Evans

The most common mode of failure observed in cemented orthopaedic implants is aseptic loosening of the prosthesis over time. This occurs as a result of fatigue failure of the bone cement under different loading conditions. Although a great deal of research has been carried out on the fatigue crack development of poly(methyl methacrylate) (PMMA) bone cements, the effects of different loading frequencies at low and high stress intensities are not well understood. Therefore, the aims of this study are to determine the effects of loading PMMA bone cement at different stress intensities and loading frequencies, as seen in-vivo, and the effects of changing these parameters on fatigue crack propagation. To achieve these aims, disc compact tension (DCT) samples with chevron notches were made and Krak Gages (Russenberger Prufmaschinen, Neuhausen am Rheinfall, Switzerland) were attached to monitor crack growth. The bone cement used in this study was the Cemex System, which uses a cement gun to mix and apply the material into the cavity. From standard compression and bending tests it was found that the cement made using this system had an average compressive strength of 86.66±5.52MPa, an average bending modulus of 3696.06±121.13MPa and an average bending strength of 51.95±4.14MPa. These values are within the normal range of acrylic resin cements for implants and above the minimum requirements of the ISO5833:2002 standard. A program has been written that loads the DCT samples with a stress intensity of 0.2MPam1/2, 0.6MPam1/2 and 1.0MPam1/2 at a frequency of 1Hz, 2Hz, 5Hz, 10Hz and 20Hz. The crack was allowed to grow 0.2mm at each frequency and the frequencies were increased (1Hz to 20Hz) then decreased in magnitude (20Hz to 1Hz) for each of the stress intensities.

This experimental design enables much more sensitive detection of small changes in crack growth rate than a conventional test where the crack grows through the entire range of δK at a single frequency. By repeatedly varying the loading within the same specimen the effects of variation between specimens can be removed, revealing significant differences in crack growth rate. The results provide important information on bone cement when loaded in conditions similar to those seen in-vivo and how frequency and stress intensities affect the fracture mechanics of PMMA.


N. Conlisk P. Pankaj C. R. Howie

Study Aim

Femoral components used in total knee arthroplasty (TKA) are primarily designed on the basis of kinematics and ease of fixation. This study considers the stress-strain environment in the distal femur due to different implant internal geometry variations (based on current industry standards) using finite element (FE) analyses. Both two and three dimensional models are considered for a range of physiological loading scenarios – from full extension to deep flexion. Issues associated with micro-motion at the bone-implant interface are also considered.

Materials and methods

Two (plane strain) and three dimensional finite element analyses were conducted to examine implant micro-motions and stability. The simple 2D models were used to examine the influence of anterior-posterior (AP) flange angle on implant stability. AP slopes of 3°, 7° and 11° were considered with contact between bone and implant interfaces being modeled using the standard coulomb friction model. The direction and region of loading was based on loading experienced at full extension, 90° flexion and 135° flexion. Three main model variations were created for the 3D analyses, the first model represented an intact distal femur, the second a primary implanted distal femur and the third a distal femur implanted with a posterior stabilising implant. Further each of the above 3D model sets were divided into two group, the first used a frictional interface between the bone and implant to characterise the behavior of uncemented implants post TKA and the second group assumed 100% osseointegration had already taken place and focused on examining the subsequent stress/strain environment in the femur with respect to different femoral component geometries relative the intact distal femur model.


Alister Hart Gwynneth Lloyd Shiraz Sabah Barry Sampson Richard Underwood Philippa Cann Johann Henckel Professor Justin Cobb Angus Lewis Martyn Porter Sarah Muirhead-Allwood John Skinner

SUMMARY

We report a prospective study of clinical data collected pre, intra and post operation to remove both cup and head components of 118 failed, current generation metal on metal (MOM) hips. Whilst component position was important, the majority were unexplained failures and of these the majority (63%) had cup inclination angles of less than 55 degrees. Poor biocompatibility of the wear debris may explain many of the failures.

BACKGROUND

Morlock et al reported a retrospective analysis of 267 MOM hips but only 34 head and cup couples (ie most were femoral neck fractures) and without data necessary to define cause of failure. The commonest cause of failure in the National Joint Registry (NJR) is unexplained.


I. H. Khan S. Nicol M. Jackson F. Monsell J. A. Livingstone R. M. Atkins

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the majority of deformities, however distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We found the described technique involving constructing a line perpendicular to a line from the tip of the greater trochanter to the centre of the femoral head inaccurate, particularly if the trochanter is abnormal. We devised a novel technique which accurately determines the CORA and extent of distal femoral deformity, allowing accurate correction.

Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylized as a block. A line bisecting the axis of the proximal femur is then extended distally to intersect the joint. The angle (Θ) between the joint and the proximal femoral axis and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of the deformity, permitting accurate correction.

We examined the utility and reproducibility of the new method using 100 normal femora. Θ = 81 ± sd 2.5. As expected, Θ correlated with femoral length (r=0.74). P (expressed as the percentage of the distance from the lateral edge of the joint block to the intersection) = 61% ± sd 8%. P was not correlated with Θ.

Intra-and inter-observer errors for these measurements are within acceptable limits and observations of 30-paired normal femora demonstrate similar values for Θ and p on the two sides.

We have found this technique to be universally applicable and reliable in a variety of distal femoral deformities.


S E Johnson-Lynn A McCaskie M A Birch

Aim

To control the growth and function of osteoblasts on Titanium alloy surfaces produced by electrochemical patterning.

Methods

Samples of Ti6Al4V were prepared with three different finishes; no surface preparation following machining, polishing on a grinding wheel with sequential grit papers up to 4000 to achieve a mirror finish and treatment in a flat electrochemical cell with a 3M sulphuric acid in methanol using 9V supplied over 60 seconds to produce a surface with defined nano/microscale roughness. Glass coverslips were used as control surfaces. Surfaces were seeded with primary rat calvarial osteoblasts and incubated in Dulbecco's Modified Eagle Medium with 10% (v/v) sera for 24 hours before fixing and performing immunofluorescence staining with anti-vinculin antibody. Photomicrographs of the surfaces were analysed with Image J and analySIS FIVE programs. Results for cell number, cell area, focal adhesion area and polarity (lack of roundness) were analysed (using the Mann Whitney test) for ANOVA using SPSS.


WS Khan S Dheerendra DS Johnson JG Andrew TE Hardingham

Introduction

Mesenchymal stem cells are a potential source of cells for the repair of articular cartilage defects. We have previously demonstrated that the infrapatellar synovial fat pad is a rich source of mesenchymal stem cells and these cells are able to undergo chondrogenic differentiation. Although synovial fat pad derived mesenchymal stem cells may represent a heterogenous population, clonal populations derived from the synovial fat pad have not previously been studied.

Materials and Methods

Mesenchymal stem cells were isolated from the infrapatellar synovial fat pad of a patient undergoing total knee arthroplasty and expanded in culture. Six clonal populations were also isolated before initial plating using limiting dilution and expanded. The cells from the mixed parent population and the derived clonal populations were characterised for stem cell surface epitopes, and then cultured as cell aggregates in chondrogenic medium for 14 days. Gene expression analyses; glycosoaminoglycan and DNA assays; and immunohistochemical staining were determined to assess chondrogenic responses.


S. Panchani D. Melling J. Moorehead S. Scott

AIM

When a hip is replaced using a posterior surgical approach, some of the external rotator muscles are divided. The aim of this study was to assess if this surgery has a long term affect on hip rotation during activities of daily living.

METHODS

An electromagnetic tracking system was used to assess hip movements during the following activities:-

Activity 1. Picking an object of the floor in a straight leg stance.

Activity 2. Picking an object of the floor when knees are flexed.

Activity 3. Sitting on a chair.

Activity 4. Putting on socks, seated, with the trunk flexed forward.

Activity 5. Putting on socks, seated, with the legs crossed.

Activity 6. Climbing stairs.

Measurements were taken from 10 subjects with bilaterally normal hips, 10 patients with a large head hip replacement, 10 patients with a resurfacing head and 10 patients with a small head hip replacement. All the hip replacement patients were at least 6 months post-op, with an asymptomatic contra-lateral native hip for comparison. Sensors were attached over the iliac crest and the mid-shaft of the lateral thigh. Data was collected as each activity was repeated 3 times. The tracker recorded hip rotation at 10 hertz, with an accuracy of 0.15 degree.


E. Pegg M. Youseffi

ABSTRACT

The friction and lubrication behaviour of four Biomet ReCap components with a nominal diameter of 52 mm and diametral clearance ranging from 167-178 μm were investigated using a friction hip simulator. Friction testing was carried out using pure bovine serum and aqueous solutions of bovine serum (BS), with and without carboxymethyl cellulose (CMC), adjusted to a range of viscosities (0.001-0.236 Pas). The Stribeck analyses suggested mixed lubrication as the dominant mode with the lowest friction factor of 0.07 at a viscosity of 0.04 Pas.

INTRODUCTION

The femoral resurfacing systems provide an alternative to hemi and total hip arthroplasty and offer several unique advantages including large resurfacing heads (>35–60 mm diameter) allowing increased range of motion (and stability) over the traditional 28 mm artificial hip joints, with excellent tolerances and surface finish leading to a reduction in wear, as well as preserving primary bone with the femoral canal remaining untouched. This work has investigated the friction and lubrication behaviour of four 52 mm metal-on-metal Biomet ReCap components with a clearance of 167-178 μm using serum-based lubricants.


M.B. Ian Pallister Wendy R Francis James C Stanley Juan de Dios Robinson Duncan Avis

The timing of definitive fracture fixation after Damage Control Surgery (DCS) remains a problem. Our unit employs a pragmatic approach, timing definitive surgery when the patient's clinical condition is judged satisfactory. Previous data implies fixation may result in a significant ‘second hit’ if executed <5 days after admission and DCS.

The response to definitive fracture fixation in adult major trauma patients requiring DCS (MT ISS>25, n= 11) with fractures of the femoral shaft, pelvis or acetabulum were studied in comparison to patients with those fractures in isolation (IF n=21) and uninjured comparable surgical controls (SC n=12). Interleukin-8 (IL-8), IL-6 and sIL-6R levels, and neutrophil CD11b & monocyte HLA-DR expression were studied at admission, preoperatively and on days 2 & 5 post-operatively. Patients were divided into those undergoing definitive surgery within the first 5 days of admission (MT1st5 & IF1st5) or later (MTL & IFL).

IL-8 levels were elevated in MT patients throughout, suggesting a proinflammatory state, whereas IL-6 levels were elevated but then declined steadily. This was independant of timing of surgery. The only post-operative rise observed was in IL-6 in SC patients.

sIL-6R levels were increased in MT compared to IF patients post surgery. This elevated state, following increased IL-6 levels may be associated with resolution of the inflammatory response.

CD11b expression in the MT group was unaffected. HLA-DR expression was reduced in the MT1st5 group, and post surgery in SC and IF1st5 groups.

No post op cases of ARDS/MODS were diagnosed.

These data suggest there is no associated detrimental effect upon the systemic inflammatory response even when undertaken less than 5 days from admission & DCS, and thus support a pragmatic approach in timing definitive fracture surgery based upon the patient's clinical improvement.


R.G. Pearson T. Kurien K.S.S. Shu B.E. Scammell

Objective

To determine the reliability, reproducibility, variability and validity of the Osteoarthritis Research Society International (OARSI) Osteoarthritis Cartilage Histopathology (OACH) system and Mankin Histopathology – Histochemical Grading System (HHGS) when applied to the characterisation of the osteoarthritic human knee.

Method

Kellgren-Lawrence and Line Drawing Atlas (LDA) radiology scores clinically graded the knees of ten patients undergoing total knee arthroplasty due to osteoarthritis. The tibial plateaux were scored using the Modified Collins (MC) and Société Française d'Arthroscopie (SFA). Three observers, twice scored, using both the OACH and HHGS systems across a single complete medial and lateral tibial plateau transect taken to include the region with the most severe OA lesion. Intra and inter-observer reliability, reproducibility, variability and validity were quantified, and the correlation between the two histopathology scoring systems was calculated.


Mr Madhavan C Papanna Mr Naved Yasin Mr Sabapathy Sundararajan Mr Kim

Objective of the study

To determine if the location and pattern of knee pain as described by the patients using the knee pain map was comparable with the intra articular pathology found on arthroscopy as well as to facilitate diagnosis based on pain.

Methods

There were Sixty consecutive patients with acute and chronic knee pain participating in the study and they subsequently underwent arthroscopy of the knee joint as therapeutic or diagnostic procedure in day surgery.

Those patients with extra articular pathologies, referred pain hip, back and foot were excluded from the study.

All the participants were consented for the study; subjective data was recorded on the standardised knee pain map that included visual analogue pain scale preoperatively on the day of admission for arthroscopy.

The findings of the arthroscopy including EUA were recorded on the on standard arthroscopy forms used in our department by the operating surgeon.


G Abbas C Thakar J McMaster

Introduction

The use of the dynamic hip screw is common practice for the fixation of intertrochanteric fractures of the femur. The success of this procedure requires accurate guide wire placement. This can prove difficult at times and can result in repeated attempts leading to longer operating time, multiple tracks and more importantly greater radiation exposure to both patient and operating staff. We hypothesised that rather than using the standard anterior-posterior projected image (Figure 1) of a proximal femur, rotating the intensifier image (Figure 2) so that the guide wire appears to pass vertically makes it easier to visualise the projected direction of the guide wire.

Methods

Fifty Specialist Registrars, thirty participating in the London hip meeting 2009, ten from Oxford and ten from Northern deanery orthopaedic rotations were involved in the study. They were presented with standard AP and rotated images of the femoral neck on paper using 135 degree template to replicate the DHS guide.

The participants were asked to mark the entry point on the intertrochanteric area of femur on the image where they would have placed the guide wire. They did this on both standard AP and rotated images aiming for the centre of the head of the femur. Fig. 1 Standard AP image Fig. 2 Rotated image


J. Li S.L. Evans E. Blain S. Piccinelli C.A. Holt D. Dini M. Accardi

Patient specific knee modelling has the potential to help understand the development of the mechanically induced degenerative disease, Osteoarthritis. A full joint contact model of the knee involves modelling the bones, ligaments, articular cartilage (AC) and meniscus, as well as, the kinematics and geometry of real joints. These finite element models will inevitably require great computational resource to run and it is desirable to find resource effective material model formulations which can accurately describe the mechanical behaviour of the soft tissues. Biphasic models (BIMs) have long been established as an effective formulation for modelling AC. However, the swelling behaviour caused by changes in the ionic phase is a major recovery mechanism and is neglected in the BIMs. It is therefore believed that BIMs alone are insufficient to fully describe the mechanical behaviour of AC. Instead, a thermal analogy method which is generically a BIM that includes the swelling behaviour has been thought to be suitable and has been validated against literature data using material parameters optimized to match the numerical and experimental results. To ensure the model is suitable for patient specific modelling where it will have the ability to reflect the individual AC material properties of the patients in the mechanical behaviour it predicts, two experiments have been planned and are currently being carried out using bovine AC. The first experiment is to investigate the diffusivity of the tissue in solutions of different molarity by measuring the change in tissue weight over time. Eleven explants are taken from the same bovine articular joint using a 6mm biopsy punch and are left in 10mM of PBS overnight to ensure ionic equilibrium has been reached before experiments are carried out. The explants are then placed in PBS solutions of molarities ranging from 0mM to 10mM and weighed at regular time intervals. In the final stage, the explants are then lyophilized and weighed for determining the volume of water in the tissues. Using Archimedes principle, the change in porosity of the tissue is found. A preliminary study has shown that explants submerged in a solution of 5mM has an approximately 4% change in weight after the first 24h and a further 1.73% change in the following 24h. Control specimens left in a solution of 10mM had a 0% change in weight. The second experiment is to carry out mechanical loading on the AC specimens while submerged in a solution of different ion concentrations. Experiments with various loading conditions are being investigated to explore their efficacy for validation. Preliminary compression tests have been carried out where steps of 1% strain was applied, giving a total of 10% strain. Between each step, strain was held constant until full relaxation has been achieved. The reaction force measured from the second experiment in conjunction with data collected from the first experiment will be compared to results predicted in the numerical model. This will allow the determination of whether thermal analogy is adequate or whether more complex triphasic models need to be considered. Furthermore, the development of these experimental methods will contribute to the validation of other AC material models in the future.


N Silikas D Watts G S Batra

Despite the increasing use on uncemented implants, cement continues to be used for hip and knee replacement in both primary and revision cases. Whilst the exact clinical relevance of reducing cement porosity, and thereby increasing its strength, is unclear in such applications, successive generations of mixing and implanting have all concentrated on reducing the amount of air in cement.

The aim of the present study was to elucidate whether the use of a power tool mixing device could reduce cement porosity more than the use of mixing under vacuum conditions alone. Furthermore, we determined if variability in cement porosity could also be reduced with power tool mixing compared with hand mixing under vacuum conditions. Cement was mixed in three different ways in a Stryker cement mixing cartridge. For group 1, cement was mixed by hand with no vacuum. For group 2, cement was mixed manually under vacuum. For group 3, cement was mixed under vacuum using the Stryker Revolution system. For all three groups, cement was stored and mixed at the same temperature and humidity. To study cement porosity, we used 3-dimensional computerised microtomography, a technique which has previously been used by other investigators. Porosity for the sample in group 1 was 9.4%, and for groups 2 and 3, mean sample porosity was 1.8% (SD 1.3) and 1.1% (SD 1.0) respectively. The large difference in porosity between group 1 and the other groups was evident on visual examination. These pores were absent when vacuum was applied. This confirms the results of several studies that have shown significant cement porosity under non-vacuum mixing conditions, even when there is strict adherence to mixing methods. Under vacuum conditions, using the Stryker Revolution system, further small reduction in cement porosity was achieved compared with manual mixing. Both Groups 2 and 3 showed variations in porosity between specimens from the same batch (intra-batch) and between batches (inter-batch). Individual specimens also demonstrated regional variations in internal porosity. Whilst the absolute reduction in overall porosity was small between the two groups (0.7%), the results favoured mixing using a rotary power tool. In addition the Revolution device was of great benefit from an ergonomic perspective. It enabled low porosity specimens to be mixed with greater ease, homogeneity and reproducibility than with manual mixing. Using the Revolution device was operator independent and involved less effort. This is likely to be of benefit in the operating room. In current practice, staff members often do not work with the same surgical team on a repeated basis, so the surgeon is likely to get greater cement consistency with such a device. It is likely to be easier to mix cement well for less experienced members of the surgical scrub team. Whilst an experience operator may be able to produce a mix of cement with very low porosity by manual mixing, it is still likely to be higher than one mixed using a power assisted device. Also, since porosity of following is related to cement working time, greater reproducibility will aid the surgeon when timing insertion of components, provided other environmental conditions remain constant.


E. Pegg M. Youseffi

ABSTRACT

The viscosity and shear stress versus shear rate relationship for pure bovine serum (BS) and its aqueous solutions with and without carboxymethyl cellulose (CMC) were investigated. BS and diluted BS without CMC showed pseudoplastic flow curves up to a critical shear rate of ∼100 s-1 above which a Newtonian flow with significant rise in shear stress was observed. The viscosity flow curve for the diluted BS+5g CMC showed only shear thinning up to a shear rate of 3000 s-1 whereas diluted BS+1g or +2g CMC showed similar flow curves to pure BS. The shear rate application modified the flow behaviour of BS from a pseudoplastic to a Newtonian flow depending on its purity and CMC content. Friction factor was dependent on viscosity and clearance with mixed lubrication as the dominant mode within the viscosity range 0.001-0.044 Pas.

INTRODUCTION

Pure BS and diluted BS are used as in vitro lubricants for tribological studies. Boundary, mixed and fluid film lubrication are the mechanisms involved in the lubrication of both natural and artificial joints. Clearance and lubricant viscosity will influence the nature of contact between the articulating surfaces. The objectives of this work were to study the flow properties of serum-based lubricants with different viscosities and the correlation between the rheological properties and frictional (and lubrication) behaviour of large diameter Biomet ReCaps with various clearances.


R G Morris S E M Lawson

Osteoarthritis is a joint condition affecting an estimated eight million people in the UK. The kinematics of walking and the impact experienced are thought to play an important role in the initiation and progression of the disease. Previous studies have looked the effect of osteoarthritis on the kinematics of walking in a laboratory environment. This work is part of the Newcastle Thousand Families Study which has followed a cohort of 1142 members since birth in 1947. Optoelectronic gait analysis methods are unsuitable for this environment, so inertial measurement units are being used. This study focuses on the validation of a protocol using inertial sensors to assess gait in the clinical environment. The sensors measure orientation in three dimensions. Our hypothesis was that an attachment position that minimises the movement of the sensor relative to the segment during gait was more important than the proximity of the sensor to anatomical landmarks. The effect of sampling rate, fatty tissue movement and material type were also tested Seven sensors (Xsens, Netherlands) were attached to participants on top of the foot, on the tibial plateau, on the lateral surface of the femur 10cm proximal to the lateral epicondyle, and over the sacrum. Attachment is by Velcro straps over the top of clothing for the waist, thigh and shank sensors, and with double-sided hypoallergenic tape on the foot. Four calibration movements are performed followed by a walking trial of ten paces down a corridor at a self-selected speed. Data is recorded wirelessly at a sampling rate of 50Hz. The calibration movements and trials are repeated twice and the time taken is 20 minutes. Measurement of the joint angles in the sagittal plane was used to assess the effect of changing the sensor position, simulating fatty tissue movement, and variation of material type underneath the sensor. The foot and thigh sensors were displaced in the distal direction by up to 10cm, the shank and waist sensors were displaced in the proximal direction by 5cm. Material types of different elasticity were tested. Fatty tissue movement beneath the straps was simulated using hydration gel packs. Each attachment scenario was repeated five times on a single subject. A “normal” attachment scenario was used to establish a baseline for repeatability of hip, knee and ankle angle measurement (mean±standard deviation of 49±1.28°, 61.5±1.28° and 33.5±0.69° respectively). Repeatability is comparable to that reported for an opto-electronic system (45±1.8°, 63±1.9° and 36±1.5°). Displacement of the foot, shank and waist sensors had no effect on the repeatability. Displacement of the thigh sensor decreased the repeatability for the knee and hip joint angles (52±3.22° and 62.5±2.91°). As the thigh sensor moved closer to the knee the movement artefact experienced increased. Altering sampling rate and simulated fatty tissue did not decrease repeatability. Of the materials tested, denim had the greatest affect, decreasing hip and knee angle repeatability (50.0±2.04° and 61.0±1.75°). A sensor attachment position that minimises sensor movement relative to the segment has been shown to produce the greatest repeatability, irrespective of their proximity to bony landmarks. This is particularly true for the femur sensor.


B.J.R.F. Bolland D.J. Culliford J. Maskell J.M. Latham D.G. Dunlop N.K. Arden

Objective

To determine the use of oral anti-inflammatory drugs use in the year before and the two years after primary total hip (THR) or knee (TKR) replacement, and to assess whether this varied according to the Body mass Index (BMI).

Design

Population based retrospective case control study.


G. E. R. Thomas D. J. Simpson H. S. Gill S. Glyn-Jones D. J. Beard D. W. Murray EPOS study group

Femoral stem varus has been associated with poorer results. We report the incidence of varus/valgus malalignment of the Exeter polished, double taper design in a multicentre prospective study. The surgical outcomes at a minimum of five year and complication rates are also reported.

A multicentre prospective study of 987 total hip replacements was undertaken to investigate whether there is an association between surgical outcome and femoral stem malalignment. The primary outcome measure was the change in the Oxford hip score (OHS) at five years. Secondary outcomes included the rate of dislocation and revision.

The incidence of varus and valgus malignment were 7.1% and 2.6% respectively. There was no significant difference in OHS between neutral and malaligned femoral stems at 5 years (neutral, mean = 40.2; varus, mean 39.3, p = 0.465; valgus, mean = 40.9, p = 0.605). There was no significant difference in dislocation rate between the groups (p = 0.66). There was also no significant difference in revision rate (p = 0.34).

This study provides evidence that the Exeter stem is extremely tolerant of varus and valgus malalignment, both in terms of outcome and complication rate.


H. Quasnichka B.C. Kerr A. Wright S. Roberts C. Hughes B. Caterson

Fragmentation of SLRPs, including decorin, biglycan, lumican, keratocan and fibromodulin, has been shown to occur in osteoarthritic articular cartilage. We have previously shown an increased expression of lumican and keratocan, in osteoarthritic articular cartilage. The long-term aim of this project is to develop ELISAs for the detection of SLRP metabolites, and validate these potential biomarkers with synovial fluid and serum samples from a large cohort of normal and osteoarthritic patients. Initially, we aimed to determine whether SLRPs could be detected in synovial fluid and whether they were post-translationally modified with glycosaminoglycan (GAG) attachments; and whether bovine nasal cartilage (BNC) would be a plentiful source of native SLRP for ELISA development.

Proteoglycans were extracted from BNC in guanidine hydrochloride. BNC extract and bovine synovial fluid was separated on an associative CsCl gradient. BNC CsCl cuts containing sulphated GAG were further purified using anion exchange chromatography. SLRPs in each fraction were detected using Western Blotting. Human recombinant lumican was expressed in Chinese hamster ovary (CHO) cells. Monoclonal antibodies that recognise epitopes on the core protein of human and bovine lumican and decorin were purified from hybridoma media using Protein G and Protein A affinity chromatography respectively. Monoclonal antibody activity against native and recombinant SLRPs was then determined using a direct ELISA.

Preliminary tests showed that bovine synovial fluid contains keratocan and lumican with GAG attachments. BNC is a good source of post-translationally modified decorin, keratocan and biglycan but lumican was present predominantly without GAG attachments. Human recombinant lumican was successfully expressed with GAG attachments by CHO cells. Initial tests showed that the mAb against decorin was able to detect native decorin, with GAG attachments, in direct ELISA conditions. We have identified a plentiful source of native SLRP and begun ELISA development to ascertain whether these proteoglycans are potential biomarkers of OA.


A.L. Jones K.A. Hing

Background, Context and Motivation

“Increases in reconstructive orthopaedic surgery, resulting from advances in surgical practice and the ageing population, have lead to a demand for bone graft that far exceeds supply.”…Traditional bone grafting methods have been linked with a number of negative issues including increased morbidity due to secondary operation site and action as a vector for spread of disease. (Hing 2004). A solution to these insufficiencies would be the creation of a synthetic osteoinductive bone graft material. This would vastly improve bone graft surgery success rates and expedite post-op recovery times. The aim of this study was to classify then explore the dissolution rates of three experimental hydroxyapatite/silicate apatite synthetic bonegrafts in physiological solutions, (phosphate buffered saline, (PBS) +/− serum proteins, (PBS +FCS). The overall objective being to identify whether there is an explainable significant difference in ion exchange that could be behind the osteoinductive phenomena.

Methods Used

Classification of the apatite samples, (HA, SA1 and SA2), was conducted via X-Ray diffraction, FTIR-PAS Spectroscopy and SEM with EDS analysis. A dissolution experiment of the experimental apatites was conducted in PBS and PBS + FCS solutions, over time periods of 1, 2 and 4 hours, and at 1, 2, 4 and 8 days, with repeat measures.


Mr Saqib Noor Ms Cerianne Pridham Mr Tim Fawcett Professor Y.T. Feng Professor Oubay Hassan Mr Ian Pallister

Introduction and aims

Biomechanical testing has been a cornerstone of the development of surgical implants for fracture stabilisation. To date most fracture surgery implant design and testing has been dominated by the use of standard bench top biomechanical testing. Although such methods have been used to successfully reproduce certain clinical observations, there are very clear limitations. More recently however, computerised engineering technology using finite element analysis (FEA) has been used to research orthopaedic biomechanical testing. This study aims to use FEA technology to further understand proximal femoral fractures, simulating falls, recreating fracture patterns and analyse fracture fixation devices for such fractures.

Study design and results

In a multi-disciplinary collaboration, novel clinically relevant models were developed at Swansea University using advanced computational engineering. In-house software (developed initially for commercial aerospace engineering), allowed accurate finite element analysis (FEA) models of the whole femur to be created, including the internal architecture of the bone, by means of linear interpolation of Greyscale images from multiaxial CT scans. This allowed for modeling the changing trabecular structure & bone mineral density in progressive osteoporosis. Falls from standing were modeled in a variety of directions, (with & without muscle action) using analysis programs which resulted in fractures consistent with those seen in clinical practice.

By meshing implants into these models and repeating the mechanism of injury in simulation, periprosthetic fractures have been successfully recreated.


Kevin Buckley Pavel Matousek Anthony W. Parker Allen E. Goodship

In this study we explore the hypothesis that there is a correlation between the ratio of the intensities of specific peaks of the Raman spectrum of bone tissue and the material properties of that particular type of bone. Raman spectroscopy is a powerful analytical technique capable of providing rich chemical information on the composition of skeletal tissue matrices and it has been used extensively to interrogate bone in the past. Spectra are presented of a selection of animal bones, each having greatly differing material properties, the differences having been produced by evolution in response to their greatly differing functions. The main examples described are deer antler (a bone naturally selected for toughness), tympanic bulla from a fin whale (naturally selected for stiffness) and the intermediate ‘standard’ bone from adult mammalian limbs which must be both tough enough to resist fracture and stiff enough to resist deformation during physiological loading (from an ovine femur in our case). In order to illustrate the specific relationship between material properties and Raman spectra additional mineralized tissues also with differing functions and of known Young's moduli are also introduced. The results show that a strong correlation exists between the mineral to collagen ratio of these different bone tissues as measured with Raman spectroscopy and their (previously published) Young's moduli. Raman spectra have been retrieved through skin and tissue in other studies in the past, an amalgamation of refined versions of those in vivo techniques with the work introduced here paves the way for the emergence of novel systems for assessing the material properties of bone tissue at specific anatomical sites in vivo in the future.


G Abbas GSJ Chuter JR Williams

Introduction

Primary Total Elbow Replacement (TER) is gaining popularity as a primary treatment option for osteoporotic fractures of the elbow, particularly in patients with low demand. The aim of this study was to assess the clinical and functional efficacy of TER as a primary treatment for comminuted distal humerus fractures in the elderly.

Methods

We retrospectively reviewed twenty-three patients (22 females and 1 male) who were treated with primary total elbow replacement for complex, intra-articular fractures of the distal humerus in the elderly between March 2000 and January 2010. The average age of the patients was seventy-five years (ranging from 66 to 94 years). Postoperative elbow function was assessed using the Mayo Elbow Performance Score. The radiological assessment was performed using antero-posterior and lateral radiographs done at follow-up appointments.


TA Howard S Canty

The price per total knee replacement (TKR) performed is fixed but the subsequent length of hospital stay (LOS) is variable. The current national average for LOS following TKR is six days. LOS is an important marker of resource consumption, has implications in patient satisfaction, and is used as a marker of hospital quality. The aim of this study was to describe the temporal change in demographics between 2004 and 2009, and to identify intra-operative factors and patient characteristics associated with a prolonged LOS that could be addressed to improve clinical practice. We performed a retrospective cohort review of 184 patients (2004 n=88, 2009 n=96) who underwent primary TKRs at Chorley District General Hospital. The median LOS in 2009 was eight days compared to ten days in 2004, an average of 3.5 days less (p < 0.001). Patients were significantly younger (p < 0.001) in 2009 (median 66 years) compared to 2004 (median 74 years), with both years having a similar female predominance. There was no significant change in the BMI or American Society of Anesthesiologists score between 2004 and 2009. This data suggests that block contracts with the private sector has not influenced the demographics of patients being treated in the NHS. Intra-operative factors including the use of a peripheral nerve block, the surgeon grade, the day of the week the operation was performed, the operation length, and the change in pre- to post-operative haemoglobin were not found to significantly increase the LOS (p = 0.058, p = 0.40, p = 0.092, p = 0.50, p = 0.43 respectively). Cemented TKRs had a median LOS of nine days compared to eight for uncemented implants (p = 0.015). However, patients with a cemented implant were on average 6.2 years older than patients with an uncemented implant (p < 0.001). Using Cox proportional hazard regression modelling, the occurrence of a post-operative complication (p < 0.001), female sex (p = 0.024), advancing age (p = 0.036), and the need for a blood transfusion (p = 0.0056) were the most significant factors for prolonging the LOS. Patients who were given a transfusion stayed a median of 13 days compared to nine for those who did not (p < 0.001). The median pre-operative haemoglobin for those who required a transfusion was 11.85g/dl compared to 13.6g/dl for those who did not (p < 0.001). Being obese or morbidly obese did not significantly prolong the LOS (p = 0.95).

In conclusion, this study highlights significant patient characteristics which are associated with a prolonged LOS following TKR. The relatively low pre-operative haemoglobin in patients requiring a blood transfusion is a potential target for reducing the LOS.


F.E. Donaldson P. Pankaj A.H.R.W. Simpson

A significant source of failure for external fixation devices is loosening of the fixation implant. As bone competence drops with ageing or disease such as osteoporosis, the risk of loosening is likely to increase. However it is not clear how fixator configuration should be adapted to minimise loosening in weaker bone. The aim of this study was to assess the effect of bone competence on the yielding of bone tissue surrounding fixation implants, and thereby inform the selection of fixator configuration to minimise loosening. External fixation of the tibial midshaft using half-pins and Illizarov wires was modelled using finite-element analysis. Half-pin configurations of two and three stainless steel and titanium pins pins were assessed. Illizarov wire configurations of two and four wires were studied, over a range of wire tensions. Bone competence was varied by changing the cortical thickness and elastic properties of the bone fragments to approximate: a) young, high-density bone, b) middle-aged, mid-porosity bone and c) old-aged, severely porous bone. Bone elastic properties were taken from a recent study of cortical bone conducted by the authors. The interaction between implants and bone was modelled with contact analysis, enabling realistic separation. Implant loosening was included using a bone-specific, strain-based yield criterion. Regions where bone tissue yielded were identified as likely sites of loosening. In all cases loading was applied to simulate a one-legged stance.

Half-pin fixation

Increasing the number of half-pins from two to three produced an approximate 80% reduction of yielded bone volume in all age groups. The volume of yielded bone increased with ageing, approximately three times greater in old-aged bone than in young bone. In the young and middle-aged cases yielded bone never penetrated the full cortex. Contrastingly, the full cortex was yielded in the old-aged bone fragments for both two- and three-pin fixation. In all cases the volume of yielded bone was greater at the pin(s) nearest to the fracture gap. The use of titanium pins increased the volume of yielded bone around half-pins by approximately 1.7 times. These results suggest bone competence, number of half-pins, location of half-pins and half-pin material all significantly influence implant loosening.

Illizarov wire fixation

Increasing the number of Illizarov wires reduced the volume of yielded bone by approximately 60% in all age groups. The volume of yielded bone increased with ageing by a factor of approximately 2.0 times from young to old bone. Bone yielding never progressed through the entire cortex; it reached a maximum of 70% of the cortical thickness in two-wire fixation of the old-aged bone fragment. This is a possible reason for the lower rate of loosening in Illizarov wire fixation as compared to half-pin fixation. Increasing wire tension reduced the volume of yielded bone. These results suggest that bone competence, number of wires, wire tension and wire arrangement significantly influence loosening.


Y. Kulikov D. Griffin

Study aim

There is an ever increasing demand for quality clinical trials in surgery. Surgeons' co-operation and enthusiasm to participate are important, if not crucial in success of such studies, especially if they are multi-centred. Clinician's individual uncertainty (equipoise) about a case has been often cited as an ethical basis for inviting a patient to take part in a clinical trial. This study aims to establish current attitudes of surgeons participating in a national multi-centred randomised controlled trial and explores an on line tool for instant assessment of collective uncertainty (equipoise) for individual clinical cases eligible for a trial.

Study design

Surgeons taking part in the UK Heel Fracture Trial were invited to take part. If agreed, they were asked to evaluate treatment prognosis for eligible for the trial anonymised cases of calcaneal fractures online by means of specially designed system. The cases were published on a password protected website on ad-hoc basis during the three years course of the trial. Their responses were submitted instantly on line.


K.W. Chan H.C. Koh A.I. Zubairy

INTRODUCTION

Warfarin remains the treatment of choice for the majority of patients with venous thromboembolism, atrial fibrillation and valvular heart disease or valve replacement unless contraindicated. Poor management of patients on warfarin often leads to delay in surgery, life threatening bleeding during or after operation and unnecessary delay in discharge from hospitals in United Kingdom.

METHODS

We carried out a prospective study on patients who were on warfarin and underwent elective and emergency orthopaedic procedures during period of study- August 2007 to April 2008. All patients included in the study were identified from admission notes during period of study. All data regarding indications for warfarin, pre and post procedures INR, elective or emergency orthopaedic procedures and complications were collected using a standard proforma.


Peter J. Dacombe Rhys G.E. Clement James Woodard Opinder Sahota

Background

Fractured neck of femurs cause substantial morbidity and mortality in elderly patients and represent a huge financial burden to the NHS. Hip fracture patients are generally malnourished on admission, often having poor nutritional inpatient intake, hindering recovery and increasing chances of “unfavourable outcome.” Nutritional care is included in intercollegiate guidelines for management of fractured neck of femur patients, but is nutrition a management priority in clinical practice?

Study Aim

To evaluate protein and energy intake of acute fractured neck of femur patients depending on admission MMSE, and compare these to department of health targets.


D Hindmarsh J Davenport V Selvaratnam G Ampat

Background

Recent articles in the medical press highlight the potential dangers of Cauda Equina Syndrome (CES). CES has the highest rates of litigation due to its long-term neurological impairment, which can lead to devastating outcome on patients. The aim of this study was to assess health care professionals knowledge with regards to the urinary symptoms of CES and the timeframe in which treatment should be offered.

Objectives

To assess health care professionals knowledge with regards to urinary symptoms of CES and when treatment should be offered.


M. Griffin G. Mc McLauchlan

The reintroduction of hip resurfacing has raised the possibility of whether it could offer a better outcome in sporting and work activity after surgery compared to total hip replacement.

Questionnaires were analysed from 125 total hip replacement (THR) and 108 hip resurfacing (HR) patients regarding participation in sport in the year after their surgery and returning to work they were employed at prior to their surgery. The two groups had similar average age (61 vs 60) and pre-operative Oxford hip scores (41 vs 38).

Seventy-one of one-hundred and twenty-five THR patients compared to 76/108 HR patients participated in sporting activity in the year after their surgery. When including only patients that played sport before their surgery 54/75 THR and 66/83 HR patients returned to same sporting activity level after their surgery. Of the patients that worked before surgery 35/44 THR patients compared to 70/74 HR patients returned work to after their surgery.

There is significant difference quantity of patients participating in sporting activity after HR and THR (fishers exact test, p value=0.04). However there is no significant difference in quantity of patients returning to sporting activity after HR or THR including only patients that played sport before their surgery (fishers exact test, p value=0.35). There is a significant difference in the quantity of patients returning to work activity after HR and THR (fishers exact test, p value= 0.02). HR has a better outcome in patients participating in sport after surgery compared to THR however there is no benefit for patients that are active pre-operatively. More patients return to work after HR than THR.


Pranay Bhushan Mathew Varghese Rajender Gupta

Flexion Deformity of knee is the most common deformity in post polio residual deformity. Wilson's release, supracondylar osteotomy etc have been described for its treatment. We present our result of fractional hamstring lengthening followed by gradual distraction using threaded rod in hollow tube to treat flexion deformity of knee. This retrospective study included 150 cases (80 males and 70 females) with the mean of 15 years (8-22yrs). The mean duration of deformity was 6 years (2 – 14yrs) with mean follow up 0f 3 years. The mean preoperative flexion deformity was 45degree (110 – 30 degree) with a mean pre operative further flexion of 110 degree (130 – 90) .20 cases were had a crawling gait and 10 cases were wheel chair bound. Flexion got corrected to 0 degree in 110 cases (P value <0.01). Post operative mean arc of motion was 80degree We had 10 cases who could not tolerate plaster and hence were put on traction . 20 cases had knee stiffness on removal of plaster which could not improve on physiotherapy. 10 cases had superficial infection cured with dressings.

Our findings indicate that this method is very effective in the treatment of flexion deformity of knee with complication of knee stiffness in older cases


Joseph Alsousou Daniel Butler Omar Bourma Fiona Lecky Keith Willett

Introduction

It has been suggested that the transition phases of implementing daylight saving time (DST) may impact on serious or fatal injuries sustained as the result of road traffic collision (RTC). The aim of this study is to explore the effects of transitions into and out of daylight saving time on the incidence of such injuries.

Method

This is a retrospective comparative observational study of 11-year of data submitted prospectively to the Trauma Audit Research Network (TARN) between 1996 and 2006. Data for 4 weeks before and after time transition in spring and autumn of each year was collected. The time periods selected reflect those hours with maximum light level changes due to time alterations (2-hour around sunrise and 4-hour around sunset). Travellers outside those hours are unlikely to be affected by the changes.


D C Molony J Kennedy A Cassar Gheiti J H Mullett

Background

The treatment of olecranon fractures frequently involves the use of tension band fixation. Although associated with high union rates, this method has a high incidence of morbidity associated with soft tissue compromise and limitation of range of movement requiring frequent re-operation for removal of metal.

Objectives

We describe the use of a simple jig to ensure intramedullary placement of longitudinal K-wires and compare the accuracy of placement of wires using this device with the traditional free hand method.


AP Monk DJ McKenna DJ Simpson DJ Beard N Thomas HS Gill

The heat produced by drills, saws and PMMA cement in the handling of bone can cause thermal necrosis. Thermal necrosis could be a factor in the formation of a fibrous tissue membrane and impaired bony ingrowth into porous prostheses. This has been proposed to lead to non-union of osteotomies and fractures, the failure of the bone-cement interface and the failure of resurfacing arthroplasty.

We compared three proprietary blades (the De Soutter, the Stryker Dual Cut and the Stryker Precision) in an in-vitro setting with porcine tibiae, using thermocouples embedded in the bone below the cutting surface to measure the increases in bone temperature.

There was a significant (p=0.001) difference in the change in temperature (δT) between the blade types. The mean increase in temperature was highest for the De Soutter, 2.84°C (SD: 1.83°C, range 0.48°C to 9.30°C); mean δT was 1.81°C (SD: 1.00°C, range 0.18°C to 4.85°C) for the Precision and 1.68°C (SD: 0.95°C, range 0.24°C to 5.67°C). Performing paired tests, there was no significant difference in δT between the Precision and Dual Cut blades (p=0.340), but both these blades had significantly (p=0.003 for Precision vs De Soutter, p<0.001 for Dual Cut vs De Soutter) lower values for δT than the Dual Cut.


Y.M. Wilkie C.D. Kerr N. Conlisk P. Pankaj

Several previous studies have examined the mechanical environment in the femur using computational modelling. In particular the proximal femur has been extensively studied using finite element (FE) analyses. This study considers the issues associated with modelling with special interest in the distal femur. FE models require appropriate input on the geometry of the system being considered, material properties of different components, loading regimes and boundary conditions (i.e. the manner in which the system is supported). This study focuses on the last two of the above. A number of models with variable levels of complexity; and different boundary and loading conditions were considered. The simplest loading and boundary conditions considered comprised load applications at the tibio-femoral joint with the proximal femur artificially restrained. More complex models had the femur fully supported on muscles and ligaments. In each case the stress-strain environment in the femur was examined. The results show that the sophistication of the model needs to be based on the answers being sought from the analysis. Some good predictions on the mechanical environment can be made with relatively crude models. For example the stress-strain behaviour in the vicinity of the knee joint was found to be reasonably well predicted by the model that was artificially restrained in the mid-femoral region. Further while different models can be used for comparing different scenarios (e.g. forces during the gait cycle) true quantitative measures are strongly dependent on experimental loading data. The study also shows that it is important to generate and evaluate models of increasing complexity in order to maintain transparency with respect to the influence of different parameters associated with loading and boundary conditions.


M. Dando V. Sparkes

Aim

To identify differences in hip muscle strength, knee valgus during a single leg squat (SLS),and function between subjects with Greater Trochanter Pain Syndrome (GTPS) and healthy(H) subjects. To determine associations between pain, function, hip strength and SLS in GPTS subjects. Study Design: Observational study of 14 (3 male 11 female) PFP patients (mean symptom duration 17 months), matched for age height and weight with 14 healthy (H) subjects, All subjects fulfilled specific inclusion and exclusion criteria. Appropriate Ethical approval was obtained. Measures for both groups were Knee valgus angle during SLS using 2D motion capture and SiliconCoach software for measurement of knee valgus angles, hip abduction, internal and external rotation muscle strength using hand held dynamometry, visual analogue scale for pain. Lower Extremity Functional Scale (LEFS). All measures were taken on the affected leg for GPTS subjects and matched for the equivalent leg in healthy group. Strength was reported as a percentage of body weight. SiliconCoach was reliable for intra-rater reliability of knee valgus angle (ICC.996).

Results

There were no significant differences in age, height and weight (p=.85,.57,.51 respectively). Significant differences existed in hip abduction strength p=.005(GPTS13.72 (7.65), H21.49 (5.55)) and LEFS p=0.001(GPTS 57.28(16.55), H76.92(4.44)). There were no significant differences in internal and external rotation and knee valgus angles p=.509, p=.505, p=.159 respectively. There was a negative correlation between pain and function r=.879) p=0.001) and a moderate positive correlation between function and hip abduction strength r=.428 (p=.127).

This preliminary study shows that patients with GPTS have reduced strength in hip abductor musculature when compared to healthy subjects. This may be due to pain inhibition; however the true causes of pain need to be determined. Pain and to a lesser extent hip abductor strength appears to have an effect on function in GPTS patients. In summary the results indicate that hip abductor muscle strengthening and management strategies to reduce pain should be included in the rehabilitation programmes of patients with GPTS. Further research with larger numbers of subjects should be developed to investigate this subject.


M. Minshull V. Sparkes

Aim

To determine differences in knee valgus angles produced during a single leg squat and hip muscle strength between healthy subjects and patients with patellofemoral pain (PFP). To determine correlations between variables of hip muscle strength, knee valgus angle and pain. Study design: Observational study of 20 (8 male 12 female) healthy (H) subjects, matched for age height and weight with 20 (8 male 12 female) PFP patients (mean symptom duration 46.75 weeks). All subjects fulfilled specific inclusion and exclusion criteria. Appropriate Ethical approval was obtained. Measures for both groups were Knee valgus angle during a single leg squat using 2D motion capture and SiliconCoach software for measurement of knee valgus angles, hip abduction, internal and external rotation muscle strength using hand held dynamometry, visual analogue scale for pain. Strength was reported as a percentage of body weight. All measures were taken on the affected leg for PFP subjects and matched for the equivalent leg in healthy group. SiliconCoach was determined to be reliable for intra-rater reliability of knee valgus angle (ICC.996).

Results

There were no significant differences in age, height and weight (p=.59,.51,.26 respectively). Significant differences existed in hip abduction strength p=.001(PFP 19.93(9.2), H 32.22(8.26)), Hip internal rotation p=0.001 (PFP 12.94(4.35), H 19.53(6.36)), Hip external rotation p=0.001(PFP 10.00(3.07), H 16.26 (4.62)), Knee Valgus Angles p=0.001(PFP 5.31(2.59), H 2.29 (2.35)). No correlations existed between any of the variables including pain.

This preliminary study shows that patients with PFP have larger knee valgus angles when doing a single leg squat and significantly weaker hip muscle strength when compared to healthy subjects. The reason for larger knee angles during single leg squat could be hypothesised as being due to weak hip abductor muscles not sufficiently controlling the alignment of the femur. However no correlations were found for these measures, nor were they found for any of the other variables including pain level. In summary the results indicate that hip musculature strengthening of the rotators and abductors and measures to reduce knee valgus angle should be included in the rehabilitation programme of patients with PFP. Further research with larger numbers of subjects should be developed to investigate this subject.


P. Bills R. J. Underwood P. M. Cann A. Hart

INTRODUCTION

There is increasing worldwide interest in the assessment of wear in explanted hip components. This is due is part to high profile failures of orthopaedic components in the US, whilst in the UK hip resurfacings have been experiencing a higher than expected failure rate. The reasons for these failures are not well understood, with data from the NJR suggesting the 43% of MoM resurfacing failures are unexplained.

Wear analysis is a vital tool in determining failure mechanisms and ultimately improving the longevity of joint replacements through improved design and manufacturing control. There are currently no relevant measurement standards for the evaluation of retrieved orthopaedic components. This paper will assess two of the most commonly used techniques namely roundness measurement and co-ordinate measurement. The advantages and disadvantages of both techniques are considered in this paper.

ROUNDNESS MACHINE

The Talyrond 365 is a stylus based roundness machine. The component is located on a rotating table and the stylus measures the deviation from a perfect circle as the component is slowly rotated. The Talyrond measures a single profile to an accuracy of 30 nm and up to 72,000 data points per revolution. The air spindle has a radial accuracy of <0.02 μm and the Talymin gauge a minimum resolution of 12 nm. Individual roundness profiles can be stitched together to build up 3D cylinder maps, allowing 3D pictures of sections of explanted hip components to be generated.


H P Singh Prof J J Dias

Introduction

Isolated midcarpal motion during radioulnar deviation could be approximated to be a rotation in a plane of a radiodorsal/ulnopalmar rotation of the wrist, which may coincide with a motion plane of one of the most essential human wrist motions, known as the dart-throwing motion. This has been studied before in normal volunteers using Magnetic Resonance Imaging to study in vivo kinematics of the midcarpal joint in the wrists of normal volunteers. We present the early results of use of biaxial flexible electrogoniometer to study the range of motion in patients with four-corner fusion.

Methods

Ten patients with four-corner fusion for SLAC/SNAC wrist were assessed to study flexion-extension, radial-ulnar deviation, and circumduction motions using flexible electrogoniometers. Opposite unaffected wrist was studied to provide normal data. Angle-angle curves (Lissajous's figures) were generated to study the area under the curve and comparison with the normal wrists and also to study the deviation from the neutral axis. Five normal volunteers were also studied to calculate the area under the curve and the axis of deviation during circumduction of the wrist.