Introduction: The London Implant Retrieval Centre (LIRC) was founded to investigate the high incidence of unexplained failures of Metal-on-Metal (MoM) hips. A multidisciplinary team analyse the failed hips, investigations include CT and MRI scans, blood and synovial fluid tests, wear measurements, X-rays and clinical data from the explanting surgeons.

Wear measurements of 100 explanted hips have been carried out on a Taylor Hobson 365 Roundness Machine using the LIRC Wear Protocol. It was found that 50% of explanted cups were wearing less than 5 μm/year and 60% of components were wearing less than 10 μm/year. Wear tests on hip joint simulators predict wear rates between 2 and 8 μm/year. However, 6% of cups are wearing faster than 100 μm/year, with 16% of cups have wear patches deeper than 100 μm and that 4% have a wear patch deeper than 300 μm.

Discussion: This paper considers the common characteristics of components in this very high wearing category. Engineering parameters such as head/cup clearance, surface finish, form errors and head cup contact conditions are investigated. This is correlated with clinical data and other results from the LIRC.

Cup position is an important factor, all of the high wearing components are outside the Lewinick’s Box, however it is shown that mal position is does not always lead to extreme wear. Further analysis is taking place to calculate the size of the contact patch between head and cup (based on patient data and biomechanics) and the proximity of the contact patch to the edge of the cup.

Conclusion: The study of explanted components shows that 6% exhibit extreme wear, and although several “risk” factors can be identified, it is not clear why only a proportion of these components show extremely high wear rates. This is the subject of current investigation.

Introduction: Local problems of metal on metal (MOM) hip arthroplasty such as pseudotumours, neck thinning and osteolysis maybe related to concentrations of cobalt and chromium ions in the synovial fluid. There is little reported on these values. Our aim was to determine the range of metal ion levels in synovial fluid, and to investigate the relationship between these samples and simultaneous blood samples.

Methods: Synovial fluid and whole blood samples were taken from 30 consecutive patients at the time of revision surgery for a painful MOM hip. Aspirated fluid was not visibly contaminated with blood. Impants were in situ for a mean period of 31 months. All had normal renal function. Samples were analysed using ICP mass spectrometry and compared with 10 samples from patients without implants.

Results: The mean (and range) of synovial fluid metal ion levels were 1965 ug/l (30 to 13618) and 6265 ug/l (11 to 81630) for Cobalt and Chromium respectively. There was a good correlation between synovial and blood levels for both cobalt (R=0.65, p = 0.0001) and chromium (R = 0.59, p = 0.006).

Discussion and Conclusion: Metal ions in synovial fluid from MOM hips are generated from wear of the bearing surfaces, the correlation with blood metal ion levels, shown in this study, suggest that blood levels may be used as surrogate marker for hip wear rate. Our range of synovial fluid metal ion levels may be useful for those conducting in vitro studies on the biocompatibility of MOM hips.

High Tibial Osteotomy (HTO) is a recognised method of correction for knee joint malalignment and unicom-partmental osteoarthritis. Long-term results of this technique have been reported and are favourable. Good results have also been reported with Autologous Chondrocyte Implantation (ACI-C, MACI). Malalignment, if present, should be corrected when ACI is performed. Although results have been reported for either procedure separately, the outcomes of combined HTO-ACI remain unreported. The aim of this study was to evaluate functional outcome in patients undergoing combined HTO-ACI procedures.

Twenty three patients undergoing a combined ACI-HTO procedure were identified retrospectively from a larger trial of patients undergoing ACI for symptomatic chondral defects. The mean age of the patients was 36 (28 – 49). The mean follow-up was 54 months (12 – 108) and mean defect size was 689mm2 (range 350 – 1200). Nine patients had ACI-C and HTO, the remainder having MACI and HTO. Pre and post-operative assessment was carried out using the Visual Analogue Score (VAS), the Bentley Functional Rating Score and the Modified Cincinnati Rating System.

The Mean VAS score improved from 7.4 (4 – 10) pre-operatively to 2.9 (0 – 6) post-operatively at the latest follow-up (p< 0.0001). The Bentley Functional Rating Score improved from 2.9 (2 – 4) to 1.8 (0 – 4), which was statistically significant (p< 0.0001). The Modified Cincinnati Rating System improved from 35.2 (20 – 49) pre-operatively to 68.7 (46 – 85) post-operatively (p< 0.0001). Fourteen patients underwent biopsy of the graft site at a mean of 13.7 months: 21% of biopsies were hyaline-like cartilage, 36% were mixed hyaline/fibrocartilage, 29 % were fibrocartilage and 14% were fibrous tissue.

Combining high tibial osteotomy with autologous chondrocyte implantation is an effective method of decreasing pain and increasing function in the short term. Further evaluation of this procedure is required.

Introduction: Autologous Chondrocyte Implantation (ACI) is a treatment option for symptomatic, full-thickness chondral/osteochondral injuries. Goals of surgery and rehabilitation include replacement of damaged cartilage with hyaline/hyaline-like cartilage, leading eventually to improved level of function. Intermediate and long-term results are promising in terms of functional improvement.

Purpose: To explore the hypothesis that non-hyaline cartilage repair tissue is associated with worse functional outcome and to assess whether the quality of the repair tissue formed following ACI improves with time post-surgery.

Methods and Results: Two hundred and forty eight patients who underwent ACI at our institution were studied, having had post-implantation biopsies of the repair tissue. Mean timing of biopsy was 14.8 months (range 3–55). 59 biopsies showed hyaline tissue (24%), 67 mixed hyaline and fibrocartilage (27%), 113 biopsies were fibrocartilage only (46%) and 9 patients had a fibrous tissue biopsy result (9%). 126 patients (51%) had hyaline tissue in the regenerate and demonstrated a mean Modified Cincinnati Rating Score (MCRS) of 84 and a mean Lysholm Score of 88 at last follow-up (Group 1). 122 patients (49%) had no hyaline tissue in the regenerate and scored a mean MCRS of 71 and a mean Lysholm Score of 73 (Group 2). Both Groups 1 and 2 demonstrated a statistically significant improvement in functional outcome between pre and post-operative scores (p< 0.0001). There was significant difference in post-operative scores between Groups 1 and 2 suggesting that presence of hyaline tissue in the regenerate is associated with improved functional outcome (p< 0.05). Finally, our statistical analysis suggested that if time post-implantation doubles, then the likelihood of a favourable histological outcome increases significantly.

Conclusion: ACI forms a durable repair tissue that remodels and continues to improve in quality with time. Poor functional outcome may reflect the presence of a non-hyaline cartilage repair tissue.

Introduction: Autologous chondrocyte implantation (ACI) has been used to treat patella cartilage lesions but several studies have indicated poorer results compared to lesions on the femoral condyles. This paper investigates the effectiveness of two different methods of ACI; porcine-derived collagen membrane as a cover (ACI-C) and matrix-carried autologous chondrocyte implantation (MACI).

Methods: 124 patients (mean age 33.5) with symptomatic osteochondral lesions in the patella were selected to undergo either ACI (56 patients) or MACI (68 patients). 1 year following surgery patients underwent check arthroscopy to assess the graft. Functional assessment was performed pre-operatively, at 6 months and yearly by using the modified Cincinnati score (MCS).

Results: 37.5% of patients experienced good or excellent clinical results according to the MCS in the ACI group compared with 69.2% in the MACI group (p = 0.0011). The mean MCS improved from 43.7 pre-operatively to 49.8 2 years following surgery in the ACI group, whereas in the MACI group the improvement was from 44.6 to 60.6 (p=0.07). Arthroscopic assessment showed a good to excellent International Cartilage Repair Society score in 89.7% of ACI-C grafts and 69.6% of MACI grafts (p = 0.08). There was a higher re-operation rate (p = 0.044) in the ACI group (29%) compared with MACI (10%).

Conclusions: The results from this paper suggest that MACI is more successful in the treatment of patella cartilage lesions than ACI even though arthroscopic assessment showed the converse to be true. The higher complication and re-operation rate suggests that we should be treating such patients with MACI.

High tibial osteotomy (HTO) is a recognised method of correction for knee joint malalignment and unicompartmental osteoarthritis. The long term results of this technique have been reported and are favourable. Autologous chondrocyte implantation (ACI-C, MACI) has also been reported to have good results It is advised that malalignment, if present, should be corrected if ACI is to be performed. Although results have been reported for either procedure separately, the outcomes of combined HTO-ACI remain unreported.

To evaluate functional outcome in a group of patients undergoing combined HTO-ACI procedures.

Twenty three patients undergoing a combined ACI-HTO procedure were identified retrospectively from a larger trial of patients undergoing ACI for symptomatic chondral defects. The mean follow-up was 54 months (range 12 – 108) and the mean defect size was 689 mm2 (range 350 – 1200). Nine patients had ACI-C and HTO, the remainder having MACI and HTO. Pre and postoperative assessment was carried out using the Visual Analogue Score (VAS), the Bentley Functional Rating Score and the Modified Cincinnati Rating System.

The Mean VAS score improved from 7.4 pre-operatively to 2.9 post-operatively (p< 0.0001). The Bentley Functional Rating Score improved from 2.9 to 1.8 (p< 0.0001) whilst the Modified Cincinnati Rating System improved from 35.2 pre-operatively to 68.7 post-operatively (p< 0.0001). There was no significant difference between ACI-C and MACI. Two patients developed a non union at a mean of 13 months and a further two patients had a failure of the chondrocyte graft at a mean of 22.5 months.

Combining high tibial osteotomy with autologous chondrocyte implantation is an effective method of decreasing pain and increasing function at mean of 54 months follow-up. Further follow-up is required to assess the long term outcomes of these combined procedures.

Non-invasive expandable prostheses for limb salvage tumour surgery were first used in 2002. These implants allow ongoing lengthening of the operated limb to maintain limb-length equality and function while avoiding unnecessary repeat surgeries and the phenomenon of anniversary operations.

A large series of skeletally immature patients have been treated with these implants at the two leading orthopaedic oncology centres in England (Royal National Orthopaedic Hospital, Stanmore, and Royal Orthopaedic Hospital, Birmingham).

An up to date review of these patients has been made, documenting the relevant diagnoses, sites of tumour and types of implant used. 74 patients were assessed, with an age range of 7 – 16 years and follow up range of 4 – 88 months.

We identified five problems with lengthening. One was due to soft tissue restriction which resolved following excision of the hindering tissue. Another was due to autoclaving of the prosthesis prior to insertion and this patient, along with two others, all had successful further surgery to replace the gearbox. Another six patients required mechanism revision when the prosthesis had reached its maximal length. Complications included one fracture of the prosthesis that was revised successfully and six cases of metalwork infection (two of which were present prior to insertion of the implant and three of which were treated successfully with silver-coated implants). There were no cases of aseptic loosening.

Overall satisfaction was high with the patients avoiding operative lengthening and tolerating the non-invasive lengthenings well. Combined with satisfactory survivorship and functional outcome, we commend its use in the immature population of long bone tumour cases.

Non-bacterial osteitis (NBO), a term referring to sterile bone lesions with non-specific histopathological features of inflammation, may be either uni- or multifocal, acute (6 months) or chronic, and recurrent. Only when the condition is chronic, recurrent and multifocal is it appropriate to use the term chronic recurrent multifocal osteomyelitis (CRMO).

We present our clinical experience as the largest reported series of children with NBO to date. Of 41 children (2–16 years) diagnosed with NBO in our institution over the last 6 years, 21 (51%) had recurrent disease and 18 of 41 (44%) had multifocal disease. The most common bones affected were the clavicle, femur and tibia (in order of decreasing prevalence) accounting for 44 (63%) of a total of 70 lesions. Only one individual had SAPHO syndrome and no other patients had evidence of bowel or skin disease. In the absence of evidence for an infective aetiology, we recommend non-steroidal anti-inflammatory agents as first line therapy, and bisphosphonates only in cases of resistant disease.

On the basis of our findings we propose a patient questionnaire and protocol for investigating and managing patients who present to orthopaedic surgeons with NBO. We predict that this will benefit patients with this disorder by providing valuable information about the pathogenesis, clinical outcome and response to treatment. In the future, clarification of the pathogenesis of this disease will undoubtedly help rationalise the therapeutic approach improving both quality of life and outcome for these patients.

Introduction: The aim of the study was to review the long-term survival and outcome of 49 consecutive endoprosthetic lower limb diaphyseal replacements undertaken for neoplastic conditions.

Methods: A retrospective review of all femoral and tibial diaphyseal replacements performed between 1990 and 2009 at our specialist bone and soft tissue tumour unit was performed. Minimum follow-up was one year. Joint sparing prostheses were excluded.

Results: 49 femoral (31) and tibial (18) diaphyseal replacements were implanted into 46 patients (31 male, 15 female). Mean age at surgery was 47 years (range 9–79). Surgery was performed for malignancy in 46 cases (97%), of which 41 (89%) were primary bone and soft tissue sarcomas. The predominant pathologies were osteosarcoma (24%), malignant fibrous histiocytoma (14%) and chondrosarcoma (14%). Mean follow-up was 81 months (range 12–221 months). Survival within the follow-up group was 96% at 1 year, 79% at 5 years, and 69% at 10 years. In surviving patients, using revision, recurrence and amputation as endpoints, prosthesis survival was 91% at 1 year, 58% at 5 years, and 33% at 10 years. In total, 13 prostheses underwent revision surgery and there were 3 amputations following diaphyseal replacement. Of these 16 cases, 75% were for aseptic loosening or prosthetic failure, 13% for tumour recurrence, and 13% for infection.

Discussion: Lower limb diaphyseal endoprosthetic replacements are a useful surgical treatment method for patients with malignant neoplastic diaphyseal bone lesions requiring excision and reconstruction. This is both limb salvage and joint-sparing reconstructive surgery.

Introduction: The Musculoskeletal Tumour Society recommends that patients with musculoskeletal tumours are treated in specialist centres. Core needle biopsy is an effective method of obtaining tissue diagnosis but a dilemma arises when the material is non-diagnostic. Our aim was to evaluate the management of non-diagnostic biopsies.

Method: We retrospectively reviewed all core needle biopsies performed between 2003 and 2009 in our regional centre. Non-diagnostic biopsies were identified and management reviewed.

Results: 4,520 core needle-biopsies were performed of which 120 (2.6%) were non-diagnostic. Of these 85 (70%) were treated definitively on the basis of existing imaging, 8 (7%) required further imaging before treatment and 27 (23%) had a repeat biopsy.

Of the 27 repeat biopsies a positive histological diagnosis was obtained in 22 patients. The remaining 5 were again non-diagnostic giving a total of 98 patients being treated definitively without a tissue diagnosis.

Of these 98 cases, 39 (40%) were treated non-operatively, 37 (38%) had curettage and 22 (22%) underwent wide excision.

In the curettage group 33 out of 37 patients had a benign tumour on final histology. Four patients turned out to have intermediate/high grade tumours and subsequently underwent wide excision.

In the wide excision group, 17 out of 22 patients had an intermediate/high grade tumour on final histology. Five patients underwent an unnecessarily wide excision of a benign lesion.

None of the patients treated non-operatively turned out to have a tumour.

Conclusion: After non-diagnostic core-needle biopsy, the patient can safely be managed without tissue diagnosis, with low error rate, provided they have been subjected to a multidisciplinary discussion.

Objectives:

To determine the diagnostic performance of image-guided percutaneous core needle biopsy (CNB) in patients presenting with pathologic fractures of the appendicular skeleton.

A retrospective audit identified 129 consecutive patients presenting with pathological fractures to a specialist orthopaedic oncology unit over a 9 year period. All patients underwent percutaneous CNB using CT (n=98), fluoroscopy (n=15) or US (n=16) guidance. In all cases MRI or CT was available prior to biopsy to assess the presence and degree of extra-osseous tumour mass. The resulting sample was classified as diagnostic (Group 1) or non-diagnostic (Group 2) on histopathological study. Diagnostic performance was evaluated on the basis of the diagnostic yield and accuracy; these were related to the site of the lesion and presence/absence of extra-osseous mass.

Of 129 biopsies, 99 (77%) were classified as Group 1 and 30 (23%) as Group 2. The commonest sites of pathological fracture without associated soft tissue component and resulting in a non-diagnostic biopsy were the proximal femur and proximal humerus. The average cross-sectional diameter of lesions in Group 1 was 5.7 x 5.9cm. Of the 30 lesions comprising Group 2, no soft tissue component was identified on pre-biopsy cross-sectional imaging in 27 lesions (90%) whereas the remaining 3 (10%) showed a smaller extra-osseous soft tissue component compared to the lesions in Group 1.

Image-guided percutaneous CNB is a reliable method for obtaining a tissue diagnosis in patients presenting with a pathologic fracture of the appendicular skeleton with high accuracy rate. However, those lesions which are purely intra-osseous or have only very small extra-osseous components are likely to be associated with a non-diagnostic biopsy, and should be considered for a primary open procedure.

Elastofibroma dorsi is a rare, benign, slow-growing ‘pseudotumour’ classically presenting as an ill defined mass at the inferior pole of the scapula. Typical symptoms include mass, pain, scapular snapping and impingement like features. There is a predilection for females after the fifth decade of life. The aetiology is unclear.

We identified 15 patients (21 tumours) with a diagnosis of elastofibroma. Seven lesions were found on the left side and fourteen on the right; bilateral lesions were found in six patients. The male:female ratio was eight:seven and mean age at presentation was 60.9 years (range 40 – 71). The mean duration of symptoms (most commonly pain, mass and scapular snapping) prior to presentation was 25.8 months. Eighteen tumours were excised with a mean follow-up of 4.2 years (0.25–16). Four lesions were diagnosed by combined MRI and CT guided biopsy, the remainder identified using MRI alone. All patients were asked specifically about symptoms, occupation, family history and employment history (including hobbies). Pain was assessed using the Visual Analogue Score (VAS) and functional outcome using the Stanmore Percentage of Normal Shoulder Assessment (SPONSA) Score. Range of forward flexion of the shoulder joint was also assessed.

In the operative group, the mean VAS score improved from 4.6 (0–10) pre-operatively to 2.5 (0–8) post-operatively. Mean SPONSA scores improved from 61.5% (20 – 100) to 81.8% (30 – 100). Mean pre-operative forward flexion was 135 degrees (70 – 180), this improved to 166 degrees (100 – 180) post-operatively. A high number of patients had been involved in occupations involving heavy lifting. MRI had a 100% sensitivity in identifying elastofibroma when correlated with histopathological evaluation.

This series demonstrates that elastofibroma may be reliably diagnosed using MRI alone and, in the symptomatic patient, pain and function may be improved through operative excision.

Background: There is no consensus on the most appropriate prosthesis for treating osteoarthritis (OA) of the hip in young, highly active patients. Modern hip resurfacing is bone conserving, more stable and theoretically easier to revise than total hip arthroplasty. Early results of metal on metal resurfacing have been promising. We have compared two well matched cohorts of patients with regard to function, pain relief and patient satisfaction.

Methods: This prospective study included 2 cohorts of well matched patients treated with hip resurfacing (137 patients, 141 hips) and custom uncemented (CADCAM) stems (134 patients, 141 hips). All procedures were performed by a single surgeon. Outcome measures included Oxford, WOMAC and Harris hip scores. Statistical analysis was performed using the unpaired student’s t- test.

Results: One hundred and thirty four and 137 patients were included in the hip replacement and resurfacing groups respectively. The mean age of these patients was 54.6 years. The mean duration of follow up for the resurfacing group was 19.2 months compared to 13.4 months for the replacement group.

Pre operative oxford, Harris and WOMAC scores in the THA group were 41.1, 46.4 and 50.9 respectively while the post operative scores were 14.8, 95.8 and 5.0. In the HR group, pre- operative scores were 37.0, 54.1 and 45.9 respectively compared to 15.0, 96.8 and 6.1 post operatively. The degree of improvement was similar in both groups.

Conclusion: There was no significant difference in short term outcome between the groups of patients treated with hip resurfacing and total hip arthroplasty in the short term.

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue neoplasm most commonly presenting in young to middle-aged adults. LGFMS is an indolent tumour with a deceptively benign histological appearance. Local recurrences are not uncommon and the tumours can metastasise. A particular gene translocation, FUS-CREB3L2, has been shown to occur commonly in cases of LGFMS. The literature suggests that the FUS-CREB3L2 fusion-gene is a specific marker for LGFMS.

We report the cytogenetic analysis of 29 cases of LGFMS, and clinical outcomes of 21 patients treated surgically between 1998 and 2008 at our regional bone and soft-tissue tumour centre. The mean age was 45.4 years. The most common location of tumours in our series was the lower limb. The mean follow-up was 30.1 months (range 0 to 125 months). To date, there have been no cases of local recurrence or metastasis.

Fifteen of our patients (52.2%) were FUS-CREB3L2 translocation-positive. This suggests either that the translocation incidence in our LGFMS series is lower than other studies, or that reverse-transcriptase polymerase chain reaction (PCR) is substantially less sensitive than the literature suggests. The patients in this series testing positive presented at a younger age (38.2 years, compared to 45.6 years), and had larger tumours than their negative counterparts (mean diameter 97.6mm, compared to 65.2mm), although there was no difference in clinical outcome.

We conclude that PCR testing for the FUS-CREB3L2 translocation is a useful tool for confirming the diagnosis of LGFMS, but has no role in predicting short-term clinical outcome. In our experience it is not necessary to perform wide excision, and marginal margins are adequate. Longer-term follow-up is required to elucidate whether the previously reported recurrence and metastasis rates are a true reflection of the nature of this tumour, and may identify differences in the long-term clinical outcome between translocation-positive and negative patients.

Within a study group of 102 consecutive patients diagnosed at a supra-regional bone tumour unit with chondrosarcoma of the femur, tibia or humerus, an association with previously treated breast cancer was noted.

There were 58 female patients and 44 male patients. The study group contained six females (10%, mean age 53 years) who had previously been treated for breast cancer, a higher proportion than would be expected. They were referred following identification of a solitary area of increased activity on routine screening with isotope bone scan, presumed to be a solitary bony metastasis.

Most (86%) of this breast carcinoma sub-group had developed low-grade bone chondrosarcoma (Trojani grade 0.5-I) and only one case (14%) had developed high-grade chondrosarcoma (Trojani grade II-III).

A suspicious long bone lesion on bone scan in a patient with a past medical history of breast cancer must, therefore, not be assumed to be a metastasis without further investigation; the possibility of a chondral lesion should be considered. It is important that patients receive a full multidisciplinary team investigation prior to treatment in order to obtain the correct tissue diagnosis, as the management of these conditions is often different.

Our study suggests there may be a relationshipbetween patients previously treated for breast cancer and the development of subsequent chondrosarcoma.

Introduction: One of the most important factors affecting the outcome of revision THR of the femoral stem is the variability of femoral endosteal geometry after removal of the in-situ stem. A custom made implant would greatly reduce the inventory of the ‘Off the shelf” (OTS) components. This study presents the medium to long-term results of a cohort of patients with this revision prosthesis.

Methods: During the period November 1991 to November 1998, 158 patients were implanted with a computer-assisted design and computer-assisted manufactured (CAD-CAM) revision prostheses (Stanmore Implants Worldwide, Biomedical Engineering Unit, RNOH) by the senior author (SMA). There were 97 males and 61 females. The average age was 63.1 years (34.6 – 85.9). The indications for revision surgery were aseptic loosening (135 cases, 85.4 %), peri-prosthetic fractures (6 cases, 3.8 %), infection (12 cases, 7.6%) and liner wear (3 cases, 1.9%).

Results: At 10 years all patients reported relief of pre-operative pain and the average hip flexion was 95o (90 o –110o). Oxford, Harris and WOMAC hip scores in the pre-operative and post-operative period were 41.1, 44.2 and 52.4 respectively and 18.2, 89.3 and 12.3 respectively (p< 0.0001, p< 0.0001, p< 0.0001).

There were 6 complications (3.8%) in this series; a periprosthetic fracture of the femoral diaphysis (1), posterior dislocation (2), failure secondary to aseptic loosening of the implant (1) and deep vein thromboses (2)

Discussion: These ten year results are encouraging and suggest that there is a role for the use of custom implants in revision THR, particularly where the anatomical variance of the proximal femur makes the use of OTS implants unsuitable.

Granular Cell Tumours are rare mesenchymal soft tissue tumours that arise throughout the body and are believed to be of neural origin. They often present as an asymptomatic slow-growing benign solitary lesion but may be multifocal. One to two percent of cases are malignant and can metastasise.

Described series in the literature are sparse. We examined our database and identified eleven cases in ten patients treated surgically and followed-up for a period of over six years (May 2002 to January 2009) in our regional bone and soft tissue tumour centre.

Five tumours were located in the lower limb, four in the upper limb and two in the axial skeleton. Mean patient age was 31.2 years (range 8 to 55 years). Excision was complete in one case, marginal in five cases and intra-lesional in five cases. No specimens showed evidence of malignancy. No patients required postoperative adjuvant treatment. Mean follow-up was 19.3 months (range 1 to 37 months), with no cases of local recurrence. One case was multi-focal.

Histopathological examination revealed the classical features of granular cell tumour in all cases. Typically, tumour cells were diffusely and strongly positive for S100 protein by immunohistochemistry, whereas the other markers tested were negative.

We believe this case series to be the largest of its type in patients presenting to an orthopaedic soft tissue tumour unit. We present our findings and correlate it with findings of other series in the literature.

Purpose: To determine if Cobalt-Chrome (CoCr) femoral components of knee replacement components roughen significantly, and when significant roughening may start.

Methods:

Retrieval study:

14 knee replacement components were retrieved after revision procedures. The average surface roughness (Ra) of the articulating regions of each condyle was measured by surface profilometry and compared to Ra of non-articulating regions, which acted as controls on each implant.

In vitro testing:

Pin-on-plate testing of 6 paired CoCr pins and vacuum γ-irradiated UHMWPE discs was carried out under a force of 2.3kN at 1Hz to investigate how the articular Ra of CoCr pins varied with increasing number of cycles. Ra was measured at 0, 10, 100 and 1000 cycles using surface profilometry.

Results:

Retrieval analysis:

Average medial femoral condyle Ra was significantly greater than control Ra (p=0.040). Average lateral femoral condyle Ra was not significantly greater than control Ra (p=0.158). Significantly higher average Ra was seen on the medial condyles when compared with the lateral condyles (p < 0.05). 8/14 retrieved femoral components had ≥1 significantly roughened condyle (p< 0.05).

In vitro testing:

At 100 and 1000 cycles the Ra of the CoCr pins was significantly greater than Ra at 0 cycles (p< 0.05).

Conclusion: A large proportion of femoral components of knee replacement implants roughen significantly in vivo, a finding supported by our in vitro testing which indicates that roughening may begin very early on. This may have important implications for aseptic loosening of knee replacement components. However, the average Ra of those CoCr surfaces significantly (p< 0.05) roughened was within acceptable limits for orthopaedic implants (0.050μm).

Chondrosarcoma is the second most common primary malignant bone tumour. Distinguishing between grades is not necessarily straightforward and may alter the management of the disease. We evaluated the correlation between the pre-operative needle biopsy and excision biopsy histological grading of chondrosarcoma of the femur, tibia and humerus.

A consecutive retrospective series of 100 patients with a histological diagnosis of chondrosarcoma was reviewed. Twenty-one patients were excluded because 20 had only excision biopsy and one had only the pre-operative biopsy on record, thus this series included 79 available cases. In 11 instances, there was a discrepancy in histological grade.

Therefore, there was an 86% (68 out of 79) accuracy rate for pre-operative histological grading of chondrosarcoma, based on needle biopsy. However, the accuracy of the diagnostic biopsy to distinguish low-grade from high-grade was 90% (71 out of 79).

Introduction: While the explant device has made revision of uncemented acetabular components technically easier, the unique design of the Birmingham Hip Resurfacing(BHR) acetabular component precludes the use of the standard explant extractor. The dual radius geometry of this socket causes impingement and damage to the curved blade of this device.

A novel adaptor was designed to correct for the differential radii and enable removal of the well fixed BHR socket with the explant. We present the results of our initial experience with this device.

Method: A prospective study was performed to evaluate the effectiveness of this device for revising the well fixed BHR socket. All cases were performed by a single surgeon via a posterior approach.

The explant cup extractor was used with its standard centering head and curved blades. The size of the explanted cup, last reamer size and size of the implanted component were recorded

Results: Three males and 7 females were included. Their average age was 58.1 years (48–65). Average time to revision of the BHR sockets was 24.2 months (7–40). Average explanted cup size was 51mm (46–58) and final reamer size 53.8mm (51–59). Average final socket size was54.8 (50–62). Overall there was a mean 2.8.mm size difference between the explanted cup and the final reamer.

Discussion: The thickness of the blade of the explant was 2mm therefore only 0.8 mm of bone was lost on average. The device enables a simple reproducible removal of the well fixed BHR sockets with preservation of acetabular bone stock.