Objective: Assessment of hip function is done by surgeon and few patient based tools. These patient assessed scores do not measure range of motion. The American Academy of Orthopaedic Surgeons has outlined pain, mobility and range of motion as three fundamental aspects of joint assessment. We aimed to validate Oswestry hip score which was developed as a patient-completed self-assessment to provide both Harris hip score and Merle d’Aubigne hip score with added content to estimate hip range of motion.

Methods: 144 patients completed the Oswestry hip score, WOMAC Index and the Oxford hip score at two different occasions. The patients were seen two weeks later and filled the Oswestry hip score and a surgeon filled the Harris hip score. The study included 80 females and 64 males with a mean age of 62 years range (32–91). We assessed the reliability, validity and responsiveness of this new tool by comparing the individual domains of the Oswestry hip score to similar domains of the WOMAC, Harris hip score and Oxford hip score.

Results: The reliability of this new score was established by the Intraclass Correlation Coefficient. Internal consistency was measured by Cronbach’s alpha. The Cronbach’s alpha was 0.7, which is considered a good measure of internal consistency. Content validity of the Oswestry hip score was established by the validated domains of pain, function and range of motion of the Harris hip score. Analysis of frequency of response distribution showed normal floor and ceiling effect for any of the domains of the Oswestry hip score. Multi-method multitrait matrix analysis was used to establish the construct validity of the Oswestry hip score. There was good correlation between pain and function domains (p< 0.001). Moderate correlation was found among clinical assessment of hip movement and movement domains of Oswestry hip score (Pearson’s r=0.55; p0.001). The responsiveness of the Oswestry hip score was measured with Cohen’s effect size. An effect size of > 0.8 is considered large. The mean effect size was 2.06 (1.36–2.97).

Conclusion: A positive construct validity and high correlation with WOMAC, Oxford Hip Score and Harris hip score shows that the Oswestry hip score can give an adequate measure of hip joint function. An effect size of 2.0 shows good responsiveness of the Oswestry hip score. The Oswestry hip score can be completed by patients themselves and is therefore ideal for long-term and large scale collection of clinical outcome data.

Non-union is poorly understood. It is unknown if multipotent cells are present in non-union tissue or whether the activity of such cells is dysfunctional. Clinically, this is important as it may predict the success of novel therapies such as BMP treatments and cell-transplantation. This study aimed to study the characteristics of cell types present in human fracture non-union tissue, in comparison with bone marrow stromal cells (BMSC) from the patient and other healthy patients.

Non-union tissue was harvested (n=8) from long bones. Cells were isolated enzymatically and cultured in monolayer. BMSC were isolated by density gradient centrifugation of iliac crest biopsies. Their phenotype was assessed by FACS analysis for CD34, 45 and 105 markers. Their comparative growth kinetics was examined, as was their osteogenic and adipogenic capacity following extended culture in defined medium. Cell differentiation status was evaluated using alkaline phosphatase, von Kossa and oil-red O staining. Cell senescence was assessed via cell morphology, senescence associated Beta-galactosidase (SA-Beta)-Gal) activity.

Non-union cells grew in monolayer, but showed different morphologies; many non-union cells contained stress filaments (typical of senescent cells) or were of stellate appearance. In addition, significantly more non-union cells were positive for SA-Beta-Gal activity compared to BMSC (P=0.0006). Growth kinetics showed longer doubling times for cells isolated from non-union tissue when compared to BMSC isolated from the patient. Long term culture of non-union cells showed early growth arrest at passages 3–8. FACS analysis showed isolated cells to be CD34/45 negative and CD105 positive. Both non-union cells and BMSC differentiated along osteogenic and adipogenic lineages to varying extents.

Our novel results show that cells from non-union tissue exhibit senescence in culture. Hence, cell senescence is potentially involved in the aetiopathogenesis of non-unions. Whether or not this senescence has arisen through cell division (during failed repair attempts) or via abnormal biomechanical loading warrants further study. The influence of senescent cells on the healing process also requires investigation. Clearly these cells are able to differentiate into osteoblasts in vitro but may have an aberrant influence on union in vivo.

Objective: The aim of this study was to validate Oswestry hip score. This is a new score which was developed as a patient completed self-assessment to provide both Harris and Merle d’Aubigne hip score with added content to estimate hip range of motion.

Methods: 61 patients completed the Oswestry hip score, the WOMAC and the SF-36. Validity was tested by comparing the domains and items of the Oswestry hip score to WOMAC and SF-36. The new movement scale of Oswestry hip score was specifically validated against Merle d’ Aubinge, mobility scoring system. SPSS software was used for statistical analysis.

Results: Mean age was 56 years (range 18–83).Content validity of the Oswestry hip score was demonstrated by two main indicators for hip surgery, pain and function. Analysis of frequency of response distribution showed no floor or ceiling effect for any of the domains of the Oswestry hip score. Construct validity of the Oswestry hip score domains of pain and function showed good correlation with the correspondent domains of WOMAC and SF-36 (p< 0.001). Moderate correlation was found among clinical assessment of hip movement, Merle d’ Aubinge mobility score and movement domains of Oswestry hip score (Pearson’s r=0.55; p0.001). Correlation between Harris and Oswestry hip score was 0.63 to 0.91. Cronbach’s alpha was 0.7, showing good internal consistency.

Conclusion: A positive construct validity and high correlation with WOMAC and SF-36 shows that the Oswestry hip score is can give an adequate measure of hip joint function. The new questionnaire is brief and can be completed by patients themselves. It is therefore ideal for long-term and large-scale collection of data. Oswestry hip score does not intend to replace the clinical examination at the critical phases following hip surgery but can be a useful adjunct. We report the validity and reliability of this new tool.

Introduction: Monoclonal antibodies (mAbs) recognizing linear sulphation motifs in keratan sulphate (KS) were first developed in the early 1980’s. Over the years, ELISAs using 5-D-4 or other related anti-KS mAbs have been used in many studies monitoring increased cartilage aggrecan degradation with the onset of degenerative joint diseases. However, whilst these studies have in general been useful for monitoring some aspects of disease progression (usually in parallel with other biomarker assays), many longitudinal studies have shown efficacy in only the transient (early, mid or late) stages of the degenerative joint disease process. During the onset of degenerative joint disease, the pathological tissue attempts to repair/regenerate the cartilage, the chondrocytes thus synthesizing cartilage aggrecan with KS substitution [and chondroitin sulphate (CS) isomer composition] that is more like that found in developing or immature cartilage. This immature cartilage aggrecan contains much less KS substitution with shorter chain size and less linear sulphation motifs. Thus, during the different stages of degenerative joint disease progression one would expect to find variable changes in different linear sulphation epitopes present in the serum or synovial fluids. The aim of this study was to investigate the use of several monoclonal antibodies that recognise different sulphation epitopes [high sulphation (5-D-4), low sulphation (1-B-4) and KS-stubs (BKS-1)] to see if patterns of their expression could be used to distinguish different stages of degenerative joint disease. We have also developed ELISAs using mAbs recognising the KS-proteoglycans, keratocan (Ker 1) and lumican (Lum 1) for their quantification as potential biomarkers of osteoarthritis.

Methods: Competitive ELISAs were developed using monoclonal antibodies (mAbs) 5-D-4, 1B4, BKS-1, Ker-1 and Lum-1. Bovine corneal KS-proteoglycans pre-treated with keratanase were used as both the coating antigen and “standard” antigen on the same ELISA plate. Blood, synovial fluid and cartilage samples (surgical waste) obtained from patients undergoing arthroplasty with different Kellgren & Lawrence grades were analysed.

Results and Discussion: 5-D-4 and BKS-1 showed similar inhibition curves and relative 50% inhibition points. However, the curve obtained with 1B4 indicated lower relative expression of 1B4 epitope. Analysis of serum and synovial fluid sample with 5-D-4 mAb showed the presence of the epitope in both samples, but there was significantly less KS in serum than in the synovial fluid. Our results show that competitive ELISA for quantification of several different KS sulphation or “stub” epitopes and two KS-proteoglycans can all be quantified and compared using the same experimental conditions. These studies are ongoing as part of an Arthritis Research Campaign (UK) funded study. In addition the data indicates that keratocan and lumican are also increased in their expression with the progression of disease. Future studies will be performed in an attempt to quantify increased keratocan and lumican expression as potential biomarkers of degenerative joint disease.

Introduction: etiology of late infection after arthroplasty can be difficult to establish. Histology is the gold standard for infection in patients without inflammatory arthritis but diagnosis in inflammatory arthritis depends on culture (Atkins et al). Real-time PCR offers a rapid and direct assessment for staphylococci and enterococci infection but has not been widely assessed.

The aims of this study were

to develop the Roche lightcycler Staphylococcal and Enterococcal PCR kits to facilitate diagnosis of hip and knee prosthetic infections

Methods: uplicate, multiple tissue samples were taken (with separate sterile instruments) at the 1^st stage of revision after informed consent. One set were cultured and results interpreted by the Oxford criteria. The second set were extracted using the Qiagen DNA kit, purified (in-house method) and tested using the Roche lightcycler kits.

Results:53 patients undergoing 2 stage revision for suspected infection were recruited.15 (28.3%) had negative histology and no inflammatory arthritis; 3 with single positive cultures and negative PCR – considered contaminants.

29 patients had non-inflammatory arthritis. 14/18 (77.8%) with positive cultures had staphylococci +/or enterococci isolated and 10 PCR results correlated. The other 11 patients had negative cultures.

9 patients had inflammatory arthritis. Six were culture negative and of the other three, 2 were positive for staphylococci on culture with 1 positive by PCR.

Discussion: Negative staphylococcal PCR correlates with the isolation of staphylococci from only one sample. This agrees with the Oxford criteria that such samples may be considered contaminants. Additional positives detected by staphylococcal PCR alone are rare.

Enterococcal PCR confirmed culture positivity in 2/3 patients. An additional 5 positive PCR’s were obtained from patients’ culture negative for enterococci. It is not clear if these are false positives or more sensitive detection of enterococcal isolation.

Highly active anti-retroviral therapy has transformed HIV into a chronic disease with a long-term asymptomatic phase. As a result, emphasis is shifting to other effects of the virus, aside from immunosuppression and mortality. We have reviewed the current evidence for an association between HIV infection and poor fracture healing.

The increased prevalence of osteoporosis and fragility fractures in HIV patients is well recognised. The suggestion that this may be purely as a result of highly active anti-retroviral therapy has been largely rejected. Apart from directly impeding cellular function in bone remodelling, HIV infection is known to cause derangement in the levels of those cytokines involved in fracture healing (particularly tumour necrosis factor-α) and appears to impair the blood supply of bone.

Many other factors complicate this issue, including a reduced body mass index, suboptimal nutrition, the effects of anti-retroviral drugs and the avoidance of operative intervention because of high rates of wound infection. However, there are sound molecular and biochemical hypotheses for a direct relationship between HIV infection and impaired fracture healing, and the rewards for further knowledge in this area are extensive in terms of optimised fracture management, reduced patient morbidity and educated resource allocation. Further investigation in this area is overdue.

Introduction: The Trent arthroplasty register reported that results of Hip arthroplasty in general setup were less than that reported from specialist centres by 5%. This independent prospective study tests the hypothesis that results of Birmingham Hip Resurfacing arthroplasty from specialist centres would not accurately represent the outcome of hip resurfacing when performed in general setup.

Material and Methods: All patients were prospectively followed for at least five years at Oswestry Hip outcome centre. The surgeons carrying out the operation prospectively provided surgical details and thereafter patients were followed using Oswestry hip questionnaire (OSHIP) at fixed intervals. Survival was assessed by Kaplan-Meier method. The results were compared to the published results of BHR from specialist centers

Results: There were 679 patients, and 58 surgeons in the study. Mean age at operation was 51 years and mean follow up was 5.63 years. The predominant preoperative diagnosis was osteoarthritis. The mean OSHIP score was 89.5. There were 29 (4.2%) failures mostly due to fracture neck of femur (62%); all of them were revised to conventional THR. The Kaplan-Meier survival at seven years is 95.354%.

Discussion: Compared to the published results, there were 2 to 19 times high failure rate which is significantly higher (p=0.001) than the published studies. Hence we prove our hypothesis, as the results of BHR from specialist centres do not accurately reflect on the outcome in general setup. The discrepancy in the results that we have identified would help to identify the weak areas in the general setup, where most of the patients get benefited from BHR arthroplasty.

The Trent arthroplasty register reported that results of Hip arthroplasty in general setup were less than that reported from specialist centres by 5%. This independent prospective study tests the hypothesis that results of Birmingham Hip Resurfacing (BHR) arthroplasty from pioneering centres would not accurately represent the outcome of hip resurfacing when performed in general setup.

All patients were prospectively followed for at least five years at Oswestry Hip outcome centre. The surgeons carrying out the operation prospectively provided surgical details and thereafter patients were followed using Oswestry hip questionnaire (OSHIP) at fixed intervals. Survival was assessed by Kaplan-Meier method. Results were compared to the published results of BHR from specialist centres.

There were 679 patients, and 58 surgeons in the study. Mean age at operation was 51 years and mean follow up was 5.63 years. The predominant preopera-tive diagnosis was Osteoarthritis. Mean OSHIP score was 89.5. There were 29 (4.2%) failures mostly due to fracture neck of femur (34%). Out of 14 failures in the first year, 9 (64%) were due to fracture neck of femur. The Kaplan-Meier survival up to eight years is 95.354% in the current study.

Compared to the published results, there were 2 to 19 times high failure rate which is significantly higher (p=0.001) than the published studies. Most of the early failures were due to fracture neck of femur in the first year. Hence we prove our hypothesis, as the results of BHR from specialist centres do not accurately reflect on the outcome in general setup. The discrepancy in the results is mostly due to fracture neck of femur in the early postoperative time. The results of this study will enhance awareness of the early trend in failures. Appropriate patient selection and meticulous surgical technique will help avoid this complication in the general setup, where most of the patients get benefited from BHR arthroplasty.

Introduction: The wear particles produced from the metal-on-metal hip prosthesis causes measurable rise of metal ion levels in the patient’s body fluids. Wear of the bearing is directly related to its use. The goal of this study is to test two hypotheses. Firstly, that exercise causes increased wear particles in vivo which can cause immediate measurable rise in the serum metal ion levels. Secondly, that this rise in metal ion level is different for different types of bearings.

Material and Methods: Eighteen participants were allocated to four different groups i.e. Birmingham Hip Resurfacing prosthesis group, Cormet 2000 resurfacing prosthesis group, Thrust plate prosthesis group (28mm metasul articulation) and group four with out any metal work. Blood samples were taken immediately before, immediately after and one hour after exercise. Plasma cobalt and chromium was determined using Inductively-Coupled-Plasma-Mass-Spectrometry and Dynamic-reaction-cell respectively with detection limit of 2nmol/l each.

Results: The four patient groups were comparable. A significant increase (p< 0.005) in serum cobalt and chromium of 13% and 11% respectively, was noticed after the exercise. Rise of cobalt levels in patients with a resurfacing MOM was 8.5 times (BHR group) and 6.5 times (Cormet group) larger than in those with a Metasul (p=0.021 and p=0.047). Neither rise of metal levels nor baseline levels correlated with any other factor (p> 0.27).

Discussion: Physiologic exercise causes immediate detectable rise in the serum metal ion levels. The increase is predominantly related to the size of the bearing surface. Exercise-related-cobalt-rise could be used to assess the tribology of the different metal on metal designs in vivo for future research

In-vitro studies have shown that wear rates of the metal on metal (MOM) bearing hip prostheses decline once the bearing runs-in and the bearing subsequently enters a steady state wear phase. Baseline cobalt levels are thus expected to decline with time in patients. Several clinical studies have not found such a decline. Baseline cobalt levels are hence limited in their capacity to provide information on the wear performance of the bearing couple. We have demonstrated in a previous study that exercise causes a rise in plasma metal ion levels in patients with MOM bearing hip replacement. Would the exercise related cobalt rise be more sensitive to detect change in wear behaviour of the bearing couple? We tested the alternate hypothesis that exercise related rise in the plasma cobalt levels will correlate inversely with the duration of MOM implantation.

Sixteen patients with three different well functioning MOM bearing hip replacement [two types of resurfacing (BHR, Cormet) and Metasul] were included into the study. Patients were divided in to two groups based on time since implantation, an early group of mean 18 months and a late group of mean 57 months. Plasma levels of cobalt were measured before (baseline) and after 1 hour of maximal exercise (peak). The difference between baseline and peak for each patient provided the exercise related cobalt rise. A significant increase in plasma cobalt levels of 13% was noticed after the exercise (p < 0.005). Baseline Cobalt levels in the late group (53nmol/l) were higher than early group (44nmol/l) but the difference was not significant (p=0.45). However, the mean exercise related Cobalt rise levels was lower in late group (3.5nmol/l) than the early group (6.5nmol/l). This lower rise in cobalt level in the late group precisely reflects on the steady state wear as seen in in-vitro tests.

Baseline cobalt levels are limited in determining the in-vivo performance of the bearing couple. Exercise related rise in cobalt levels can differentiate the running in and steady state wear phases of metal on metal bearings and is thus a more accurate tool of assessing in-vivo wear performance of the bearing couple.

Introduction: Before proceeding to long-term studies, we studied early clinical results of combined Autologous Chondrocyte Implantation (ACI) and Allogenic Meniscus Transplantation (AMT). Meniscus deficient knees develop early osteo-arthritis (OA) of the knee joint. Autologous Cartilage Implantation (ACI) is contraindicated in case of meniscus deficient knees. And on contrary the Allogenic Meniscus Transplantation (AMT) is contraindicated in cartilage defects in the knee joint. But a combination of the two procedures for bone on bone OA might be a solution for this problem. This was the main purpose of our study.

Methods: We studied a consecutive series of eight patients (7 males and 1 female), with an average age= 43 years (29–58), presenting with painful secondary arthritis, due to premature loss of meniscus and chondral defect/s. Median size of the femoral defects was 8.16 cm2 and of the tibial side 2.69 cm2 All patients were treated with a combination of Autologous Chondrocyte implantation (ACI) and Allogenic Meniscus Transplantation (AMT). Chondral defects were covered with periosteum/ Chondroguide membrane, secured in place with in-vitro cultured autologous chondrocytes injected underneath the path. Meniscus placed as load-bearing washer on the surface of ACI of tibia. ACI rehabilitation protocol followed post-operatively. Assessment at the end of one year was done with self-assessed Lysholm score, histology and the MRI scan.

Results: Mean pre-operaive Lysholm score was 49 (17–75). This increased to a mean of 66 (26–87) at 1 year, an average increase of 16.4 points. Average one-year satisfaction score was 3 and they were back to all active life style. Five out of eight patients showed significant functional improvement at last post-operative follow-up (2 to 6 years; mean of 3.2 years). Complications were aseptic synovitis in 3 cases. Three failures were noted showig persistant pain and swelling in one, rupture of meniscus in second and third patient had a knee replacement. Arthroscopy at 1 year showed a stable meniscus with all healed peripheral margins in all except in one case with some thinning with no evidence of rejection. Histology of meniscus showed a fibrocartilage well populated with viable cells and the peripheral zone was well vascularised and integrated with capsule. Biopsy of ACI site was predominantly of fibrocartilage with good basal integration with subchondral bone. On MRI scan, allogenic meniscus was well integrated with capsule along the line of repair, showing foci of variable signal intensities within the meniscus. There was no evidence of meniscal subluxation in all but one case showing mild extrusion. ACI graft site showed a varied appearance, with 3 grafts showing focal grade 3to 4 changes.

Conclusion: Seven out of eight patients improved post-operatively at one year, in terms of pain relief and increased activity. It’s possible to combine these two techniques together. Short-term outcomes are satisfactory. We could not find any deleterious effects of combining these two techniques together. So we conclude that, this might act as a one step towards a biological knee replacement.

Background: Articular cartilage injuries are very common. Small defects don’t heal on their own and large defects can’t regenerate new cartilage. This would largely be due to the fact that chondrocytes are embedded in a firm and tough matrix and hence can’t migrate to the defect site to regenerate a new cartilage tissue. So ultimate fate is patient getting early osteoarthritis. Cartilage defects in the knee may be symptomatic and cause pain, swelling and catching. There are several different surgical procedures available to treat cartilage injuries, but no method has been judged superior. The ultimate aim of the treatment is restoration of normal knee function by regeneration of hyaline cartilage in the defect, and to achieve a complete integration to the surrounding cartilage and underlying bone. Arthroscopic debridement and lavage may give symptomatic relief for a limited time. Autologous Chondrocytes Implantation (ACI) was first described in 1994. Encouraging primary results were reported, and further research was promoted. Long-term results are encouraging. ACI is being done in Robert Jones & Agnes Hunt orthopaedic Hospital, Oswestry since last 8 years.

Methods: We studied a cohort of first 118 patients who underwent ACI for knee joint in this institute, focussing on their mid-term results. Patients having chondral defects were offered ACI. They all were explained the procedure and informed written consent was obtained. Patients filled in a self-assessed Lysholm forms before the operation. They also underwent pre-operative MRI scan of knee joint. ACI procedure consisted of three stages— Stage I —Arthroscopic harvest biopsy of cartilage and chondrocytes culture in lab. Stage II—Arthrotomy of the knee. The defect edges were freshened, covered by periosteum or chondroguide, which was sutured to the cartilage with 6-0 vicryl. Chondrocytes were injected underneath this patch. Post-op CPM and Physiotherapy. Stage III—1-year arthroscopic surgery. Assessment was done with Lysholm score, MRI scan, histological and arthroscopic analysis. Patients were followed up clinically thereafter with yearly Lysholm scores.

Results: 118 patients with an average age of 35 years (15–59) underwent ACI for knee in last 8 years. 93 patients had single defect, 24 had multiple (> 1) chondral defects, with mean area 4.81 cm2. MRI showed a good integration of defect with surrounding cartilage with varied signal intensities. About 55–56% patients underwent some or other form of trimming, which improved immediate results. However only 50 % of these were symptomatic. Defects on MFC did well as compared to other sites, followed by on trochlea. Defects on patella showed poor results, though the number is less for comparison. Total 79 specimens of 1-year histology showed good healing with formation of fibrocartilage (40), mixed (20) and hyaline (8), fibrous tissue (6), bone in 1 case and inconclusive in 2 cases. Mean pre-op Lysholm score was 50.16. Average score at one year was found to be 69.52.

Conclusion: Results of ACI are encouraging. Patients continued to improve slowly over a period of time, achieving maximum function between one and 2 years post-surgery. Our study showed that there after their scores remained static.

Introduction: Autologous Chondrocyte Implantation (ACI) was first described in 1994(1) and has become an increasingly widely used treatment for chondral defects in the knee. The intention of this study was to identify which patient and/or surgical factors affect clinical outcome. In order to do this, a multicentre database of patients treated with ACI was established.

Methods: Four European centres collaborating in the EuroCell project (2) contributed data. These centres have historically used different outcome measures to follow up their patients. In order to analyse this data, a method of z-transformation was used to standardise the clinical scores. This has allowed a large number of patients to be investigated even when different scores have been used. A panel of predictor variables was agreed relating to patient factors and operative technique. Linear multiple regression analysis was performed to determine which predictor variables significantly influenced clinical outcome.

Results: A total of 284 patient datasets from four centres were investigated with 1 to 10 year follow-up. In 213 datasets the Modified Cincinnati (Noyes) clinician evaluation was used (3). The remaining 73 patients had outcome data measured with the modified Lysholm score (4). Outcome was defined as the change in score to latest follow-up. Z-transformation (z-change) was performed for each score type. The regression model was: z-change = − 0.11 − 0.5*z-preop − 0.43*R4 + 0 .30*OC + 0.20*FC (R2=0.30) The regression analysis showed that the factors which affected outcome were one centre (R4), pre-operative score (z-preop), osteochondral defects (OC), and lesions of the femoral condyle (FC). Factors which were found not to affect outcome included the age of the patient, size of the defect treated, number of defects treated and time to follow-up. Variations in operative technique, including the location of the cartilage harvest, the use of fibrin sealant and the timing of patch placement, were not found to have an effect on clinical outcome.

Conclusions: The method of z-transformation is a useful way of compiling multicentre data where different outcome measures have been used. This has allowed a large dataset to be compiled and factors which influence clinical outcome to be identified.

Introduction: Many designs exist for the femoral component of cemented total hip arthoplasty, but cemented acetabular cups are largely similar. All are essentially hemispheres, made of polyethylene. An important factor determining survival time of cemented implants is cement penetration into the surrounding bone. To ensure sufficient penetration, many surgeons remove the smooth subchondral bone in the acetabulum and drill anchoring holes. This may however weaken the bone. Larger cement pressure during setting will improve penetration. For an acetabular cup, fixation at the rim is most important to prevent loosening, and therefore cement pressure should be high at the rim. A spherical geometry is not ideal to ensure high rim cement pressures. Based on a computer model of cement pressure generation during cup insertion, we designed an improved geometry to ensure higher rim pressures. The aim of this study is to compare the fixation strength of this new design to a conventional design. The effect of the design change will be compared with that of drilling anchoring holes and removing subchondral bone.

Methods: From a larger stock of young bovine acetabula, 14 similarly sized specimens were chosen. Twelve were prepared for a factorial experiment with three factors, based on three cup designs (Ogee either with or without flange, DePuy, Leeds, and the alternative design), preservation or removal of subchondral bone, and presence or absence of anchoring holes. Depth, diameter and position of the anchoring holes were chosen to optimise fixation strength. Two were prepared for replicates of two experiments with the new design, both with sub-chondral bone removed. The order of the experiments was randomised. CMW-3 cement (CMW-DePuy, UK) was hand-mixed for one minute. After four minutes, it was packed in the acetabulum and pressurised for one minute. Then a cup was inserted and manual force applied until setting of the cement. Next, acetabulum and cup were mounted in a materials testing machine and torque applied to the cup until gross failure. Applied force and displacement were sampled into a computer, and used to determine maximum torque.

Results and Discussion: Analysis was done in two steps. First, two-way ANOVA of main effects plus first order interactions was performed. Anchoring holes significantly increased strength (41±8 vs. 114±9 Nm; p=0.004, mean±SEM). No significant effect of reaming or cup design was found. For all experiments, the conventional cups with or without flange behaved almost identical. In step two, these two variations were combined into one “conventional” group, and three-way ANOVA with interactions was performed. Significant interaction between all three factors was found (p=0.02). This indicates that one unique combination (new cup design in acetabula with subchondral bone removed and without anchoring holes) achieved a high average strength. Under these circumstances, the fixation strength of the new design (114±9 Nm) was equal to the overall average achieved with anchoring holes. On average, the new design also had significantly larger fixation strength than a conventional spherical design (95±5 vs. 69±4 Nm; p=0.009). These results justify further studies.

Introduction. Leg length inequality post total hip arthroplasty is a source of patient dissatisfaction. In adult DDH femoral length equality is assumed. Empirically, a longer femur has been observed on the affected side in the presence of unilateral DDH; restoration of the hip centre in this situation may lengthen the affected leg.

Aim. Assessment of femoral length variation in adults with unilateral and bilateral DDH.

Method. Retrospective observation study of 17 adults with unilateral and 7 adults with bilateral DDH. Femoral lengths assessed using CT measurements.

Results. Unilateral DDH. The ipsilateral femur was longer in 11 patients (63%) The degree of femoral lengthening was between 5 and 10 mm. Bilateral DDH. The femur with the greater degree of DDH was longer by a mean of 7.5 19.3 mm .

Conclusion. In the presence of DDH, asymmetry of femoral lengths is common and unpredictable. Careful femoral length assessment ( with CT leg lengths) is advised preoperatively in patients with DDH. This will alert the surgeon and patient to the possible risk of post operative ipsilateral leg lengthening.

Statement of Purpose We describe the donor site morbidity of hyaline cartilage biopsy from the trochlea of the knee when used for ACI in the ankle joint.

Methods We studied 12 patients who received a two stage ACI procedure on the talus, performed by three consultant surgeons. The first stage involved knee arthroscopy and harvest of cartilage for culture and stage two the transplantation of a chondrocyte culture to the ankle joint.

During the first stage knee arthroscopy using a superolateral approach, the cartilage specimens were taken from a minor load bearing area of either the central or superolateral trochlea using a 5mm gouge.

Clinical outcomes were assessed using a patient satisfaction score and the Lysholm knee score, taken both pre- and post- operatively at 3 months and annually thereafter.

Results The mean age of the patient group was 42. The patient satisfaction questionnaires showed 11 patients to be ‘pleased’ or ‘extremely pleased’ with their ACI procedure which was sustained in the patients with up to four years follow up.

The mean Lysholm score preoperatively was 98/100. Postoperatively eight patients had a reduced score (mean reduction 14) at twelve months follow up. In those patients with new knee symptoms at one year, analysis of the Lysholm score components showed the Locking and Limp categories to be the most frequent cause of a reduced score. Two patients had repeat knee arthroscopy at 18 months and 2 years postoperatively for symptoms of catching, anterior knee pain and swelling.

Discussion The Lysholm knee score has components which may be affected by ipsilateral joint problems, which contribute to 20% of the overall score. However those patients with an abnormal Lysholm knee score postoperatively have gained an improved Mazur ankle score since their ACI.

The procedure of cartilage harvest from the trochlea of the knee has an associated donor site morbidity which is present at one year. Ninety two percent of patients were pleased or extremely pleased with their ACI procedure, despite the requirement of surgery on their knee and it would seem that the amount of early knee morbidity these patients experience is outweighed by the improvement in symptoms in the treated joint.

Ideally to optimise cartilage repair less morbid techniques to obtain cartilage need to be identified or alternatively mesenchymal stem cells could be used as an alternative source, which has already had limited success in the knee and might also be applied to other joints.

We present the early results of a bone conserving implant, the Thrust Plate Prosthesis (TPP) used for the revision of failed resurfacings of the hip in nine patients.

Four revisions were for fractured neck of femurs. The original implant in this fracture group was a McMinn resurfacing. The original acetabular component was retained. Five revisions were due to aseptic loosening. Four of the original implants in this group were Beuchal Pappas (BP) resurfacings and one was a Cormet2000 resurfacing.

In the fracture group the average age was 46yrs (34–70). The time from primary to revision surgery was 5.8 months (3–11). The Harris hip scores improved in all patients to their pre fracture level of 90 (83–99).

In the aseptic loosening group the average age was 62yrs (53–67). The time from primary to revision surgery was 121 months for the BP resurfacings and 19 months for the Cormet. The Harris hip scores also improved in this group to an average of 73.8 (50–100).

Hip resurfacing presents an attractive option for the younger patient. It is a bone conserving procedure with the added benefit of increased stability by using a large diameter head. Fracture of the femoral neck is a specific early complication. The usual treatment of this complication has been revision to a more traditional design, loosing the benefits of bone conservation.

The TPP is a bone preserving implant that has metaphyseal fixation of the proximal femur. It has satisfactory long term results (Huggler, 1993). The use of the TPP for revision of failed resurfacings has proved to be straight forward. Our early results are promising in the fracture group, but revision for aseptic loosening did not correlate with a high hip score. It remains to be proven that revision of a bone conserving hip replacement will maintain a high quality function. For the younger patient with a failed resurfacing, revision with a TPP can offer continued bone conservation.

Aim: A retrospective review of the triple pelvic osteotomies performed between 1988 and 2002 identifying the factors that may predict a favourable outcome from surgery.

Method: A case note and x-ray review identifying various parameters that influence outcome.

Results: 30 osteotomies in 26 patients have been studied. 3male and 27 female patients have been identified. All patients were symptomatic prior to surgery complaining of pain and reduced exercise tolerance. Following surgery 21 patients were satisfied with their outcome and 9 patients had poor results.

The average age of patients with a good outcome was 20.9 years. The average age of patients with a poor outcome was 30.9 years.

There was no correlation between the correction of either the Sharp angle or the centre-edge angle and outcome. Sphericity of the head was unrelated to outcome. Obesity was associated with a poorer outcome in older patients.

Conclusion: Triple pelvic osteotomy provides a reliable method of improving symptoms in younger patients with dysplastic hips. An increased rate of failure should be expected in patients over thirty years of age.

Aims: This study aims to identify whether there is seasonal variation in proximal femoral fractures in ageing population. Methods: We carried out a study to find out whether there is a definite variation in the incidence of these fractures. The number of operated proximal femoral fractures across 31 hospitals of Northwest England and Scotland were collected on a monthly basis from 1994 to 1999. This database of 27,000 operated proximal femoral fractures was assessed statistically. Results: Our analysis reveals that the incidence of these fractures during December is about 17% higher than rest of the annual mean with a 2% standard error of the mean (SEM) and in January this increase is about 22% with a SEM of 1%. These trend and pattern were observed for both intra and extra capsular fractures of neck of femur and was consistent over the five years. There was no other significant change in the incidence pattern during other months of the year. Conclusions: This study, one of the largest of its kind ever carried out, proves that there is an increase in the incidence of hip fractures in the months of December and January. There should be appropriate allocation of manpower and rehabilitation facilities during the months of December and January to tackle this seasonal variation.

Introduction: Impaction grafting has become a popular technique to revise implants. The Norwegian Arthroplasty Registry reports its use for a third of all revisions. Yet, the technique is seen as demanding. A particular challenge is to achieve sufficient mechanical stability of the construction. This work tests two hypotheses: (1) Graft compaction is an important determinant of mechanical stability, and (2) Graft compaction depends on compaction effort and graft properties. Methods: Impaction grafting surgery was simulated in laboratory experiments using artificial bones with realistic elastic properties (Sawbones, Malmö, Sweden). Bone stock was restored with compacted morsellised graft, and the joint reconstructed with a cemented implant. The implant was loaded cyclically and its migration relative to bone measured. In a second study, morsellised bone of various particle sizes and bone densities, with or without added ceramic bone substitutes, was compacted into a cylindrical mould by impaction of a plunger by a dropping weight. Plunger displacement was measured continuously. Results: Initial mechanical stability of the prostheses correlated most strongly with degree of graft compaction achieved. Graft compaction to similar strength was achieved with less energy for morsellised bone with larger particles, higher density, or bone mixed with ceramic substitutes. Conclusion: Initial mechanical stability of impaction-grafted joint reconstructions depends largely on degree of graft compaction achieved by the surgeon. Compaction depends partly on the vigour of impaction, and partly on graft quality. Higher bone density, larger particle size and mixing with ceramic particles all help to facilitate graft compaction, giving a stronger compacted mass with less effort.