Background: Autologous Chondrocyte Implantation (ACI) is widely used as a treatment for symptomatic chondral and osteochondral defects of the knee. Variations of the original periosteum cover technique include the use of porcine-derived type I/III collagen as a cover (ACI-C), and the use of a collagen bilayer seeded with chondrocytes (MACI).

Aim: To determine whether differences in clinical, arthroscopic and histological outcomes at 1 year exist between ACI-C and MACI techniques.

Methods: We have performed a prospective randomised comparison of ACI-C versus MACI for the treatment of symptomatic chondral defects of the knee on 91 patients of whom 44 received ACI-C and 47 received MACI grafts.

Results: Both treatments resulted in improvements of clinical scores after 1 year. Mean modified Cincinnati knee scores increased by 17.5 in the ACI-C group and 19.6 in the MACI group (p> 0.05). Arthroscopic assessments performed after 1 year demonstrated good to excellent ICRS graft repair scores in 79% of ACI-C grafts and 67% of MACI grafts. Hyaline-like or hyaline-like cartilage with fibrocartilage was found in the biopsies of 43% of ACI-C grafts and 36% of MACI grafts after 1 year. The rate of graft hypertrophy was 9% in the ACI-C group and 6% in the MACI group. The frequency of re-operation was 9% in each group.

Conclusions: We conclude that clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI techniques. While the MACI technique is technically attractive, further long-term studies are required before widespread adoption of this new technique.

Soft tissue balance is known to be an important factor for the success of Total Knee Arthroplasty.Traditional surgical techniques involve soft tissue releases and bony cuts to achieve the correct balance. Evaluation of balance is currently based on subjective intra-operative clinical assessment, or the feel of the knee. More recently, an instrument to objectively measure soft tissue balance following bony cuts has been developed. Soft tissues releases using this instrument may be extensive.

Hypothesis. The hypothesis is that patients who undergo more extensive releases will have poorer short-term outcome and increased complication rates compared to those who undergo less extensive releases.

Method. 506 patients aged 40–90 years underwent 526 Kinemax TKAs, performed by seven surgeons in five centres between October 1999 and December 2002. Five surgeons used traditional methods for soft tissue balancing and only took balancer measurements pre-cementation. The other two were guided by the balancer instrument and took measurements pre- and post-releases, therefore quantifying how imbalanced the knees were at the beginning of the operation. Patients were assessed by an independent observer using the Oxford Knee Score, the American Knee Society Clinical Rating System and the Roentographic and Evaluation Scoring System, with a minimum follow-up of 12 months.

Results. Extensive soft tissue releasing procedures showed no significant difference in outcome in comparison with minimal releases. For the 2 surgeons using the balancer technique, a significant difference was seen with the change in knee scores. The knees left imbal-anced had substantially lower change scores and the imbalanced – balanced group showed the most improvement. Regarding surgical technique, there was no significant difference between the groups with the Oxford Knee Score or with the Clinical Rating System. Range of movement and outcome also showed no significant difference between any of the groups. Complication rates were low, clinically representative and showed no significant difference between the groups.

Conclusions. Extensive soft tissue releases do not result in an increase in complication rate or a poorer short-term outcome. When comparing traditional and balancer guided techniques there is no difference in outcomes. Balancing an imbalanced knee significantly improves knee outcome.

Introduction: Malignant tumours of the fibula are rare and can be difficult to treat. We discuss the management and outcome of 52 patients who presented with malignant tumours of the fibula over a 15-year period between 1983 and 1998.

Methods: Data was collected prospectively and reviewed from the Bone Tumour database, medical records and by clinical review. Consecutive patients were studied and survival was calculated using the Kaplan-Meier curve.

Patients: The tumour type was Osteosarcoma (23 patients), Ewing’s sarcoma (16), Chondrosarcoma (11 – of which 10 low grade) and Malignant Fibrous Histiocytoma (2). We concentrate on the two most common frankly malignant groups: Osteosarcoma and Ewing’s. The male:female ratio of patients with Osteosarcoma was 11:12 and with Ewing’s Sarcoma was 11:5. Mean age for Osteosarcoma was 21.5 years and for Ewing’s Sarcoma was 14.2. The most common site of tumour was in the proximal fibula in both Osteosarcoma (19 / 23) and Ewing’s Sarcoma (10 / 16). The stage of disease at presentation was IIa or IIb in the majority of patients, with seven patients presenting with metastases.

Management: The current investigative procedures are Radiographs, Magnetic Resonance Imaging, Radioisotope Bone Scans, Computerised Tomography of the chest and needle biopsy whereas in the past CT of the lesion and open biopsy were common. Chemotherapy was administered as per protocol at the time of diagnosis and radiotherapy was given in selected cases. Surgery was performed on all but 3 patients, who were unfit and died. This consisted of local en bloc resection in 86.3% and above knee amputation in 6.8%.

Outcome: Whereas all the diaphyseal and distal lesions were completely excised, 9 out of 26 proximal lesions had a marginal excision, 4 of which had open biopsies. The common peroneal nerve was sacrificed in 50% of cases and this had no link to survival. The overall 5-year survival was 33% for Osteosarcoma and 40% for Ewing’s Sarcoma, with proximal lesions doing much worse than diaphyseal and distal lesions. Patients who had marginal excisions all died within 2.5 years.

Introduction: Total femoral endoprosthetic replacement can be an alternative to amputation following extensive tumour excision or in cases of severe bone loss. In skeletally immature patients the problem of leg length inequality may be overcome by the use of extendable prostheses. The aim of this study is to assess the functional outcome of patients following total femoral endoprosthetic replacement.

Methods: This is a retrospective, single centre study of 16 patients who underwent consecutive total femoral replacements between 1978 and 1999. Information was collected from the Bone Tumour database, medical records and clinical review. The prostheses were custom made by the Biomedical Engineering Department of University College London and Stanmore Implants Worldwide. The implants are composed of a Titanium alloy shaft with Cobalt-Chrome bearing surfaces, incorporating a SMILES (Stanmore Modular Individualised Lower Extremity System) knee joint. Outcome was assessed using the Musculoskeletal Tumour Society (MTS) rating score.

Sample: Eight patients were male and eight female. Mean age was 35 years (range 5–75 years). Ten patients underwent total femoral replacement as a primary procedure; nine for malignant tumour and one for hydatid disease. Of the patients with malignancy five had metastases at the time of presentation. The other indications were failed distal femoral replacement in four cases and periprosthetic fractures in the remaining two. Four children received extendable prostheses.

Results: Of the patients with malignant disease, all but one had complete tumour excision. Three patients developed local recurrence. Two patients died of metastases within one year of diagnosis and three more died within five years. Three required revision procedures. Two more dislocated at the hip joint. Other complications included infection and lymphoedema. In patients surviving longer than one year the average range of motion at the hip was 85 degrees and at the knee 80 degrees. Using the MTS rating score the mean functional outcome was 60% of normal (range 27–90%). Of the survivors one achieved an excellent result, five were good, four fair and one poor.

Conclusion: Total femoral endoprosthetic replacement can be effective in limb salvage and provide an alternative to amputation. Good functional results can often be achieved. However, the complication rate is high and the outcome extremely varied.

We compared the accuracy of image guided (ultrasound or CT) percutaneous core needle biopsy to percutaneous core needle biopsy without image guidance in diagnosis of soft tissue tumours. 140 patients with soft tissue lesion who were referred to a London bone and soft tissue tumour unit underwent percutaneous core needle biopsies of their lesion either with or without image guidance.111 of these 140 patients subsequently had surgical excision. The accuracy of image guided percutaneous biopsy and percutaneous biopsy without image was then calculated by comparing the histological results of the needle biopsy to that of the resection.

The diagnosis accuracy of unguided biopsy was 78% (36 out of 46) compared to 95% (62 out of 65) in image guided. In 6 out of the 46 patients who had unguided biopsy, there was insufficient material obtained from the needle biopsy to allow histological diagnosis. This was not the case with any of the patients who had image guided core needle biopsy.

Using image guidance, either USS or CT scan, improves the diagnostic accuracy of percutaneous core needle biopsy and must be considered in management of patients with soft tissue tumours.

Introduction: The purpose of this study is to demonstrate that definitive surgery (extraperiosteal excision) is required in patients with osteofibrous dysplasia (OFD) due to the risk of recurrence and co-existent adamantinoma. The possible link with adamantinoma is controversial with some authors believing that they are part of one histological process. This therefore provides difficulty in recommending treatment options.

Methods: Using our database 22 cases of OFD were identified. Management was diverse.

Results: Definitive (extraperiosteal) surgery, in the majority of our patients, was localized excision for small lesions (less than 50% of the bony circumference) and segmental excision followed by reconstructive surgery for more extensive ones. Seven patients had a “shark-bite” excision and a further seven were treated with fibula autografting. Of the latter group, one required further excision and bone transport due to recurrence of OFD. Five underwent bone transport & distraction osteogenesis and one had a proximal tibial replacement. Nine initially underwent curettage, but eight recurred. No recurrences occurred following localized extraperiosteal excisions and bone transport. There were three confirmed cases of adamantinoma.

Discussion: In view of the risk of association of OFD with adamantinoma, and to some extent the continuous morbidity of OFD if left untreated, we believe that radical extraperiosteal excision is indicated in most if not all cases of OFD.

Introduction and Aim: This project reports on patients treated with malignant fibula pathology at the London Bone Tumor Service with the aim of reporting on the prognosis for such patients.

Method and Results: Over a 15-year period, The London Bone Tumor Service has treated 39 patients with malignant fibula pathology: Osteosarcoma (23), Ewing’s sarcoma (16). Proximal fibula pathology was more common (29), distal (five) and diaphyseal (five). Thirty-two patients were treated with wide local excision initially, one below knee amputation, three above knee amputations, two were not fit for surgery and two died while receiving chemotherapy. Two patients required subsequent above knee amputations and one patient a hip disarticulation. Relapse was very common in proximal fibula osteosarcoma. Only 7/23 patients avoided both metastasis and local recurrence.

The five-year survival rate of osteosarcoma of the proximal fibula is 33%, distal fibula 100% and diaphyseal 100%. Ewing’s sarcoma of the proximal fibula is 40%, diaphyseal 50% and distal fibula 100%.

Conclusion: Despite relatively early presentation of symptoms, the prognosis of proximal fibula osteosarcoma and Ewing’s remains poor. Unlike the prognosis of both distal and diaphyseal pathology, which remains excellent.

Introduction and Aims: Retrospective analysis of 25 consecutive metal-on-metal proximal femoral replacements performed at our unit between 1965 and 1979.

Method: Patients were clinically evaluated using the Modified Harris hip and Enneking Scoring Systems and radiologically evaluated using the ISOLOS scoring system. The concentration of Cr, Co, Ti, Al, V, Mo & Ni in whole blood and urine was also measured by High-Resolution Inductively Coupled Mass Spectrometry and compared with controls and patients with other implants.

Retrieved prostheses (in-situ for in excess of 25 years) were analysed for roughness and wear using a Mitutoya form tracer and an electron microscope.

Results: Thirteen patients have since died, nine from metastatic disease and four from other causes. Of the remainder, 11 (44%) are still alive, five still retaining metal-on-metal articulations and one has been lost to follow-up. They have been in-situ for an average of 32 years. The average modified Harris hip score is 76 (53–93) and the average Enneking Score is 74 (63–90).

In the retrieved prostheses the contact zones were found to be smoother (Ra 0.05mm), have fewer and smaller carbides, together with evidence of ‘self-healing’ when compared to the original surface (Ra 0.32mm).

Blood and urine levels of Co & Cr were significantly elevated. Co levels were exceptionally elevated in loose prostheses, but levels quickly fell following revision.

Conclusion: We have shown the potential longevity of metal-on-metal arthroplasty. The wear seen in retrieved specimens is low and we might expect to improve the fixation by reducing the torque with apical bearing and encouraging extra-cortical bone bridging with hydroxy-apatite-coated collars. Elevated serum and urine Co levels may well predict a loose prosthesis and may be useful as a screening tool.

Introduction and Aims: We present a review of the long-term results of custom-made massive unicondylar femoral replacement for reconstruction following tumor excision, and compare the functional outcome of this procedure with prosthetic distal femoral replacement.

Method: Using our centre’s endoprosthetic database we identified and analysed all cases of massive unicondylar femoral replacement performed at our unit (group 1). Patients were evaluated for function, (Musculoskeletal Tumour Society System), and for stability (adapted from Oxford Knee Score). An age and sex-matched cohort of patients who had undergone distal femoral replacements for similar pathologies, and in who the follow-up was of a comparable time period (group 2) was evaluated in an identical manner. Statistical analysis was performed on the results.

Results: Twelve cases of massive unicondylar replacement have been performed between 1990 and 2001, for a variety of malignant and benign tumors. There have been no incidences of infection, aseptic loosening or tumor recurrence. One patient has died of metastatic disease and another has undergone revision to distal femoral replacement for osteoarthritis. Of the remaining 10 patients, nine were available for assessment

Each of the two groups consisted of five males and four females, with mean age 48 years in group 1 and 49 years in group 2. The average follow-up since surgery in both groups was 10 years. The mean MSTS and stability scores of group 1 were 83% and 3.9 respectively, and 71% and 3.2 for group 2; the difference in scores between groups was statistically significant (p< 0.02).

Conclusion: With stringent case selection criteria, the custom-made massive unicondylar femoral replacement produces a good outcome, with functional results significantly better than distal femoral replacement. This may be because a substantial proportion of the knee joint with at least one cruciate and one collateral ligament are kept intact, thus facilitating enhanced proprioception.

Introduction and Aims: ACI (autologous chondrocyte implantation) using a periosteum cover was developed by Peterson et al. Recently, the technique has been developed using a Type I/Type III collagen membrane (Chondro-Gide). A second technique MACI (matrix-induced autologous chondrocyte implantation) has evolved using a membrane with chondrocytes seeded onto its surface. Aim is to review the one and two-year results of the first 159 patients at a single regional centre.

Method: The two-stage procedure was performed with a standardised, progressive rehabilitation program. Patients were assessed clinically at three, six, nine, 12 and 24 months (pain score, Modified Cincinnati, Bentley), and arthroscopically at 12 and 24 months.

Results: 159 patients have been assessed at one year and 101 patients at two years. Of those patients reviewed at one year, 110 patients had the ACI repair with Chondro-Gide, 31 patients had the ACI repair with periosteum and 18 patients had the MACI repair. Sixty-nine percent had good or excellent results at one year and 60% at two years.

These figures represent the early results of this study performed at this unit.

Conclusion: We propose that the ACI technique is valuable for selected patients with Chondral and osteochondral defects of the knee even with large and multiple defects in the articular cartilage.

Introduction and Aims: Uni-compartmental knee arthroplasty (UKA) is appropriate for one in three osteoarthritic knees requiring replacement. An accelerated protocol enables patients undergoing UKA to be discharged within 24 hours of surgery. Before such an approach is universally accepted it must be safe, effective and economically viable. A study was performed to compare the new accelerated protocol with current standard care in a state healthcare system.

Method: A single blind RCT design was used. Patients eligible for UKA were screened for NSAID tolerance, social circumstances and geographical location before allocation to either an accelerated recovery group (Group A) or a standard non-accelerated group (Group S). The accelerated protocol included dedicated pain management and discharge support. Primary outcome was the Oxford Knee Assessment at six months post-operation, compared using independent t tests. Pain, range of movement and incidence of complications were also recorded by assessors blind to group allocation. Cost effectiveness was calculated in quality life adjusted years (QLAY) using the Euroqual instrument. The study power was sufficient to avoid type 2 errors. The study was supported by a NHS Regional R& D grant.

Results: Forty-one patients (21 group A, 20 group S) were included. Groups had comparable age and patient profiles. Average discharge time was 37 hours (1.5 days) for group A and 114 hours (4.3 days) for group S. Pain on hospital discharge was similar for both groups. No significant difference was found between groups for pain or range of movement at any time, although patients in group S regained pre-operative flexion faster than group A. One major complication occurred in each group; one infection (group S) and one manipulation for poor movement (group A). The cost per QLAY for the new protocol was 59% of the standard care.

Conclusion: The new protocol allows for safe accelerated discharge from hospital after UKA. The approach is cost-effective and should help to increase the throughput of patients who require knee replacement.

Introduction and Aim: The purpose of this study is to demonstrate that definitive surgery (extraperiosteal excision) is required in patients with osteofibrous dysplasia (OFD) due to the risk of recurrence and co-existent adamantinoma. OFD is an unusual childhood condition, which almost exclusively affects the tibia. It is thought to follow a slowly progressive course and to stabilise after skeletal maturity. The possible link with adamantinoma is controversial, with some authors believing that they are part of one histological process. This therefore provides difficulty in recommending treatment options.

Method and Results: A retrospective review of OFD was conducted. Using the Stanmore Bone Tumor Unit database, 22 cases were identified who were initially diagnosed with OFD or were diagnosed on final histology. All cases were tibial except one lesion in the ulna and one in the fibula. Management was diverse, depending on the severity of symptoms and the extent of the lesions encountered. Definitive (extraperiosteal) surgery in the majority of our patients was localised excision for small lesions (less than 50% of the bony circumference) and segmental excision followed by reconstructive surgery for more extensive ones. Seven patients had a ‘sharkbite’ excision and a further seven were treated with fibula autografting. Of the latter group, one required further excision and bone transport due to recurrence of OFD. An additional five underwent bone transport and distraction osteogenesis using the Ilizarov technique and one had a proximal tibial replacement. Nine initially underwent curettage, but eight recurred (recurrence rate 88.9%). No recurrences occurred following localised extraperiosteal excisions and bone transport. There were three confirmed cases of adamantinoma

Conclusion: In view of the risk of association of OFD with adamantinoma, and to some extent the continuous morbidity of OFD if left untreated, we believe that radical extraperiosteal excision is indicated in most if not all cases of OFD

Introduction: The treatment of bone defects that occurs following fractures, the excision of bone tumours and at revision arthroplasty surgery, often involves the use of either autologous or allogenous bone grafts. However, both grafts have limitations. The aim of tissue engineering is to produce cells within an extracellular matrix that resembles tissue, which can be implanted into a patient to heal a tissue defect. The potential to engineer bone tissue grafts from patients’ autologous cells would improve the treatment of bone defects.

Bone marrow contains cells, known as mesenchymal stem cells (MSCs), which have the ability to differentiate into osteoblasts. To create a 3-dimensional structure necessary for the reconstruction of tissue, cells need to be grown on a scaffold, for which hydroxyapatite (HA) was used, as it is osteoconductive. In living bone, increased extravascular perfusion increases new bone formation. Thus, these physiological conditions were reproduced in our novel bioreactor by perfusing MSCs seeded on porous HA scaffolds at a rate of 6ml/hr. Hypotheses: 1. Culture in this bioreactor improves cell penetration through a HA scaffold. 2. MSCs cultured on HA in this bioreactor differentiated into osteoblasts.

Method: MSCs were isolated from 8 bone marrow aspirates, which were taken from patients during orthopaedic procedures following informed consent. For each experiment, MSCs from each patient were seeded onto 2 x 1cm³ scaffolds. To test cell penetration, the HA scaffolds were cultured for 7 days, then sectioned longitudinally and the number of cells were counted at increasing depths. Observations of MSCs on HA were compared under scanning (SEM) and transmission (TEM) electron microscopy. The HA scaffolds were cultured with MSCs in the bioreactor for 5, 10 & 15 days, after which time alkaline phosphatase (ALP) and type I pro-collagen protein levels were measured.

Results: Penetration of cells through the porous HA scaffold was significantly greater when the cells had been cultured in the bioreactor (P< 0.05). Observing MSCs after 7 days in bioreactor culture under SEM, adherent fibroblastic cells formed a network over the HA. However, by 14 days the HA was covered with cuboidal cells, consistent with osteoblasts. TEM results showed that MSCs cultured on HA in the bioreactor produced organised collagen matrix after 28 days. Osteoblastic protein levels were significantly greater at each time point when MSCs were cultured in bioreactor conditions: ALP (P< 0.005) and type I pro-collagen (P< 0.05).

Discussion and Conclusions: These results show that when cultured in our novel bioreactor, MSCs penetrated uniformly through the porous HA scaffold, whereas few cells penetrated in static culture conditions. Thus, our bio-reactor significantly improves the 3-dimensional growth of cells, resembling tissue. Moreover, in this study MSCs grown on HA in the bioreactor produced significantly larger amounts of ALP and type I pro-collagen, indicating that the MSCs differentiated into osteoblasts. Observations under TEM showed extracellular collagen matrix production which, when mineralized, produces bone.

Therefore, this culture method could potentially be used to convert MSCs, isolated from patients’ bone marrow, into tissue-engineered bone.

Introduction: Bone grafts are frequently used in orthopaedic operations to augment bone healing. Autologous bone graft is the gold standard for osteogenesis, but the amount available from the patient’s iliac crest is often insufficient to fill the defect and donor site morbidity is a significant complication. Alternatively, allograft can be implanted into patients, however, processing is necessary to reduce the immunicity of the graft and the risk of transmission of infection, but this destroys osteoprogenitor cells and hence reduces the osteogenic properties of the graft. Mesenchymal stem cells (MSCs) are present in bone marrow and have the ability to differentiate into osteoblasts. Therefore our study examined the use of MCSs, from bone marrow, to enhance the osteogenic properties of allograft.

Hypothesis: MSCs cultured on freeze-dried ethylene oxide treated bone allograft differentiate into osteoblasts, thereby increasing the osteogenic nature of the graft material.

Method: After informed consent, bone marrow aspirates were taken from 10 patients during elective orthopaedic operations. MSCs were characterized using Stro-1 antibody and grown on freeze-dried ethylene oxide treated bone allograft in vitro.

The hypothesis was tested on three groups of graft, with eight samples in each group. Firstly, freeze-dried ethylene oxide treated bone graft was tested (group 2). For a negative control, allograft was heated to 70°C to denature the osteogenic proteins (group 1). The final group tested the effect of additional osteogenic supplements (100nM dexamethasone, 0.05mM ascorbic acid and 10mM (-glycerol phosphate) on MSCs on allograft (group 3).

Osteoblastic differentiation of MSCs was observed under scanning (SEM) and transmission (TEM) electron microscopy, and by measuring protein levels: alkaline phosphatase (ALP), osteopontin and type I pro-collagen over 14 days.

Results: SEM confirmed that MSCs could be successfully cultured on bone allograft. Cells grown in groups 2 and 3 were characteristic of metabolically active osteoblasts and collagen extracellular matrix was observed under TEM. The amount of ALP protein produced by MSCs cultured in groups 2 and 3 increased significantly over 14 days (P< 0.05), but there was no increase in group 1. ALP, osteopontin and type I pro-collagen production was significantly greater for group 2 than for group 1 and for group 3 than for group 2 (P< 0.05).

Discussion and Conclusions: ALP, type I pro-collagen and osteopontin proteins are known to be produced by osteoblasts during increasing cell maturation and the levels of each of these proteins increased significantly when MSCs were cultured on allograft for 14 days compared with the negative control. The addition of osteogenic supplements significantly increased production of these proteins. Furthermore, MSCs cultured in groups 2 and 3 produced extracellular collagen matrix. These results are consistent with allograft causing MSCs to differentiate into osteoblasts and that this differentiation increases with additional osteogenic supplements.

This study confirms that MSCs, derived from autologous bone marrow, could be used to increase the osteogenic potential of allograft, thereby increasing bony healing in patients.

Introduction and Aims: Retrospective analysis of all uncemented massive endoprostheses inserted at our unit in the management of primary bone tumors with a minimum follow-up of five years.

Method: The case notes and radiographs of all patients were reviewed. The group consisted of a total of 52 patients, of which four (8%) were lost to follow-up. Kaplan-Meier Cumulative Survival Graphs were created for mortality, amputation, revision and infection for the whole group and for each individual prosthesis.

Results: The mean follow-up was seven years (63–107 months). The average age at time of insertion was 19 years; 26 patients were skeletally immature. The majority of implants were distal femoral (31) and proximal tibial (14). Osteosarcoma was the most common diagnosis.

The rate of infection was 12.5%, aseptic loosening 6%, amputation due to local recurrence 10% and the mortality 21%.

All the deaths occurred within three years of the implant being inserted and were all due to systemic progression of the disease. The amputations for local recurrence occurred throughout the follow-up period, the latest being at 71 months. Revisions for infections and aseptic loosening all occurred early (within three years). All cases of aseptic loosening occurred in distal femoral replacements (10%) and were related to divergent canals. Proximal tibial replacements had the highest rate of infection (23%). Rates of infection were not higher in the minimally invasive grower (12.5 %) when compared to the group as a whole.

Conclusion: We have shown a reduced rate of aseptic loosening (6%), particularly in the skeletally immature, when compared to our unit’s results for cemented fixed hinged prostheses. The uncemented prosthesis is a successful implant that needs careful consideration, especially in the skeletally immature. Careful pre-operative planning and surgical technique are of the utmost importance.

Introduction and Aims: The treatment of cartilage defects has been revolutionised by the introduction of autologous chondrocyte implantation (ACI) over the last decade. Several studies have shown superior clinical and histological results compared to traditional treatments such as mosaicplasty. ACI involves injecting chondrocytes into the defect and sealing it with periosteum or chondroguide membrane. Recently, a new technique has been introduced which allows chondrocytes to be embedded within a matrix which is then used to fill the cartilage defect. The aim is to assess the early functional, clinical and histological results of MACI for the treatment of full-thickness cartilage defects.

Method: This is a prospective study. Fifty patients, mean age 34 (range 19–62) underwent MACI for their cartilage repair. The modified Cincinnati, Brittberg and Lysholm and Gillquist scores were used to assess functional outcome. These were compared with the results obtained in 40 patients; mean age 31 (range 15–51) treated with ACI. A review of the histology in both groups was carried out.

Results: At two-year follow-up, functional assessment using the Brittberg and modified cincinnati scoring systems, as well as objective clinical assessment, showed that more than 75% of patients had good or excellent results following treatment with either ACI or MACI. There was no statistical difference in the functional scores between the two groups (p < 0.05). Histological results were similar in both groups.

Conclusion: Our prospective study has shown that results of MACI are comparable to that obtained by ACI. Additional advantages of the MACI technique being a shorter operative time, easier technique and potential to treat larger defects.

Retrospective analysis of all uncemented massive endoprostheses inserted at our unit in the management of primary bone tumours with a minimum follow up of 5 years.

Methods. The case notes and radiographs of all patients were reviewed. The group consisted of a total of 52 patients of which 4 (8%) were lost to follow up. Kaplan-Meier Cumulative Survival Graphs were created for mortality, amputation, revision and infection for the whole group and for each individual prosthesis.

Results. The mean follow up was seven years (63–107 months). The average age at time of insertion was 19 years; twenty-six patients were skeletally immature. The majority of implants were distal femoral (31) and proximal tibial (14). Osteosarcoma was the commonest diagnosis.

The rate of infection was 12.5%, aseptic loosening 6%, amputation due to local recurrence 10% and the mortality 21%.

All the deaths occurred within 3 years of the implant being inserted and were all due to systemic progression of the disease. The amputations for local recurrence occurred throughout the follow up period, the latest being at 71 months. Revisions for infections and aseptic loosening all occurred early (within 3 years). All cases of aseptic loosening occurred in distal femoral replacements (10%) and were related to divergent canals. Proximal tibial replacements had the highest rate of infection (23%). Rates of infection were not higher in the minimally invasive grower (12.5 %) when compared to the group as a whole.

Conclusion. We have shown a reduced rate of aseptic loosening (6%), particularly in the skeletally immature, when compared to our units results for cemented fixed hinged prostheses. The uncemented prosthesis is a successful implant that needs careful consideration, especially in the skeletally immature. Careful preoperative planning and surgical technique are of the utmost importance.

Introduction: Deep infection following distal femoral endoprosthetic replacement remains an uncommon, (< 7%), but serious complication; we present the results all three-phase revisions performed at our unit.

Method: Using the endoprosthesis-survivorship database we identified and analysed 15 consecutive cases, (including MSTS functional assessment of all available patients), performed between 1993 and 2002. The primary replacement had been performed for trauma and fourteen for limb reconstruction following excision of tumour. All cases underwent a three-phase revision. The first stage involved debridement and exchange of prosthesis for a custom-made antibiotic-impregnated spacer. Following at least six weeks of intravenous antibiotics, a further endoprosthesis was inserted.

Results: Eight patients had complete clinical, radiological & biochemical resolution of infection, (mean follow-up 60 months). Mean MSTS score for this group was 83% (range 60–97%). The remaining seven had recurrence of infection, all within 18 months. Of this group, two underwent a successful second revision procedure with conversion to a total femoral replacement. Two cases are satisfactorily managed with antibiotic suppression therapy and three have required amputation. Two of these cases underwent above-knee amputation following a failed second revision, whilst the third was given a femoral stump endoprosthesis to avoid disarticulation. Revision was generally more successful in younger patients. Neither the original pathology nor the timing of revision surgery appeared to affect outcome. Negative tissue cultures from the first stage were associated with a successful result. Very high levels of inflammatory markers were associated with failure of revision

Conclusion: We recommend two-stage revision of distal femoral replacement as an effective treatment for infection, allowing limb salvage with excellent functional outcome in the majority of patients. The antibiotic phase may need to exceed six weeks in certain cases, and levels of inflammatory markers appear to be critical. If this revision fails, conversion to a total femoral replacement should be considered.

Purpose- To review the long term survival of patients, complications and functional outcome of diaphyseal replacements in 40 consecutive femoral endoprosthetic reconstructions for treatment of primary bone sarcoma.

Methods- A retrospective case study analysis was performed on all patients treated in our hospital between 1991 and 2002 with diaphyseal replacements for the management of sarcomas of femur.

Results- 40 cases (28 males and 12 females) with a mean age of 38.4 years (10–56) were identified.The indications were ostesarcoma (18), chondrosarcoma (12), MFH (4) and ewings sarcoma (6). The presenting complaints were pain (24), swelling (16) or both (6). Fibular strut graft was used in 12 cases as an adjuvant to the diaphyseal replacement. Adequate surgical clearence was obtained in 37 cases (92.5%). The average follow up period was 98 months (11–158). The patients were assessed by the Musculoskeletal Tumour Society (MSTS) scoring system. The average MSTS score was 19 (range 16–22). The average range of motion at the knee was 94° (range 74°–126°). Twenty nine remained disease free at review. 16 patients died at a median of 28 months (11 to 124) – 6 from metastatic disease and 10 from other causes. The cumulative complication rate was 18%- wound debridement (5%), infection (3%), revision surgeries (10%–4 cases- periprosthetic fracture n=1, implant breakage n=1 and implant loosening n=2.) One patient needed amputation for recurrence.

Conclusion-.Surgical management of bone tumours using diaphyseal endoprosthesis is an effective method of treatment which allows the patient to retain a high level of function and range of motion.

Introduction: We present a review of the long-term results of custom-made massive unicondylar femoral replacement for reconstruction following tumour excision, and compare the functional outcome of this procedure with prosthetic distal femoral replacement.

Method: Using our centre’s endoprosthetic database we identified and analysed all cases of massive unicondylar femoral replacement performed at our unit (group 1). Patients were evaluated for function, (Musculoskeletal Tumour Society System), and for stability (adapted from Oxford Knee Score). An age and sex-matched cohort of patients who had undergone distal femoral replacements for similar pathologies, and in who the follow-up was of a comparable time period (group 2) was evaluated in an identical manner. Statistical analysis was performed on the results.

Results: Twelve cases of massive unicondylar replacement have been performed between 1990 and 2001, for a variety of malignant and benign tumours. There have been no incidences of infection, aseptic loosening or tumour recurrence. One patient has died of metastatic disease and another has undergone revision to distal femoral replacement for osteoarthritis. Of the remaining ten patients, nine were available for assessment Each of the two groups consisted of 5 males and 4 females, with mean age 48 years in group 1 and 49 years in group 2. The average follow-up since surgery in both groups was 10 years. The mean MSTS and stability scores of group 1 were 83% and 3.9 respectively, and 71% and 3.2 for group 2; the difference in scores between groups was statistically significant, (p< 0.02).

Conclusion: With stringent case selection criteria, the custom-made massive unicondylar femoral replacement generally produces a good outcome, with functional results significantly better than distal femoral replacement. This may be because a substantial proportion of the knee joint with at least one cruciate and one collateral ligament are kept intact, thus facilitating enhanced proprioception.

Purpose: The purpose of this study was to determine whether the low rate of mechanical loosening of the SMILES rotating hinge distal femoral endoprosthesis relates to the hydroxyapatite (HA)-coated, grooved collar of the femoral component.

Methods and results: A database was used to identify two groups of cases of primary distal femoral replacement with a custom-designed and manufactured SMILES endoprosthesis at our unit; those with the collared femoral component (“collar group”), and those without a collar (“non-collar group”). From these two groups, patients were pair-matched for age and length of bone resection. We performed a retrospective review of serial biplanar pairs of radiographs of each patient, assessing radiolucent lines and extracortical bone pedicle. 11 matched pairs were identified, (14 females, 8 males), with a mean age of 36 years, (range 16–66). The pathology was primary bone tumour in 20 cases, (17 malignant, 3 benign), and metastatic disease in 2 cases. Mean length of follow-up was 85 months, (range 27–122). Radiolucent line score (RLS) progression over time was significantly lower in the collar group, (0.01 vs 0.73, p=0.001) (fig. 1 & 2), as was the mean final RLS, (2.72 vs 7.81, p=0.02). Mean RLS per radiographic quadrant was 0.56 in cases in which a bony pedicle was ingrown onto the prosthesis, (exclusively in the collared-group), 2.41 in cases in which the pedicle was not ingrown, (most prevalent in the non-collared group), and 1.02 in those cases without any pedicle formation, (ANOVA analysis, p=0.0002).

Conclusion: This study demonstrates that the HA-coated, grooved collar significantly reduces the progression of radiolucent lines, and consequently the overall RLS, explaining the reduced rate of mechanical loosening of the SMILES prosthesis. A bony pedicle that does not incorporate onto the prosthesis surface may be associated with an increase in radiographic loosening.

Retrospective analysis of 25 consecutive metal on metal proximal femoral replacements performed at our unit between 1965 and 1979.

Methods. Patients were: clinically evaluated using the Modified Harris Hip and Enneking Scoring Systems and radiologically using the ISOLOS scoring system.

The concentration of Cr, Co, Ti, Al, V, Mo & Ni in whole blood and urine was also measured by High-Resolution Inductively Coupled Mass Spectrometry and compared with controls and patients with other implants.

Retrieved prostheses (in situ for in excess of 25 years) were analysed for roughness and wear using a Mitutoya form tracer and an electron microscope.

Results. Thirteen patients have since died; nine from metastatic disease and four from other causes. Of the remainder, eleven (44%) are still alive, five still retaining metal on metal articulations and one has been lost to follow up. They have been in situ for an average of 32 years. The average modified Harris Hip score is 76 (53–93) and the average Enneking Score is 74 (63–90).

In the retrieved prostheses the contact zones were found to be smoother (Ra 0.05?m), have fewer and smaller carbides together with evidence of ‘self-healing’ when compared to the original surface (Ra 0.32?m).

Blood & urine levels of Co & Cr were significantly elevated. Co levels were exceptionally elevated in loose prostheses but levels quickly fell following revision.

Conclusion. We have shown the potential longevity of metal on metal arthroplasty. The wear seen in retrieved specimens is low and we might expect to improve the fixation by reducing the torque with apical bearing and encouraging extra-cortical bone bridging with hydroxy-apatite coated collars. Elevated serum and urine Co levels may well predict a loose prosthesis and may be useful as a screening tool.

When managing malignant bone tumours in the distal femur with limb salvage, resection and reconstruction with a distal femoral replacement (DFR) conventionally entails prosthetic replacement of the knee joint. In younger patients it is desirable to try to preserve the knee joint. We now use a new Joint-Sparing distal femoral prosthesis in those cases where it is possible to resect the tumour and preserve the femoral condyles. Purpose of study: To look at our early results with knee joint preserving DFR’s. Methods: Between June 2001 and March 2004 the prosthesis was implanted in 8 patients (5 males and 3 females) aged between 8 and 24 years at the time of surgery. The diagnosis was osteosarcoma in 6 cases and chondrosarcoma in 2 cases. All patients were followed regularly and knee range of movement was recorded as well as any complications that occurred. Patients were functionally evaluated using the MSTS Scoring System. Results: Six of the patients had a mean follow-up of 20 months (range 8–33) and in this group 4 had good knee flexion with a mean flexion of 122° (110–130), 1 patient had fair flexion of 60° and 1 patient had poor flexion of 20°. The mean fixed flexion deformity in the 3 patients who had such a deformity was 10° (5–15). There were no intraoperative complications but the patient with poor flexion required an arthrolysis and because of the poor result is under consideration for conversion to a conventional DFR. Two patients had follow-up periods of 3 months or less and are still in their early rehabilitation period. One patient in this group developed sepsis that resolved after an open washout. Conclusions: Our early results with this prosthesis, in the patients with adequate follow-up, have been good in the majority but the two cases of fair and poor knee flexion are disappointing. This particular problem may relate to design and technical factors, which will be discussed in detail.

Purpose: To determine the mode of presentation of soft tissue sarcomas to a tertiary centre and the factors associated with a delay in diagnosis and referral.

Methods and Results Between 2000 and 2002, we identified 120 patients with primary soft tissue sarcomas histologically verified at our institution. We reviewed the case histories, referral letters and the histology reports in all cases. The mean age of the study group was 54.5 (range 10 to 91 years). Pathological diagnoses included 32 liposarcomas, 20 malignant fibrous histiocytomas, 19 synovial sarcomas, 12 leiomyosarcomas, 9 fibrosarcomas, 7 spindle cell sarcomas, 4 pleomorphic sarcomas, 3 identified only as high grade soft tissue sarcomas, 3 epithelioid sarcomas, 2 extraosseous Ewing’s sarcomas, 2 malignant round cell tumours and one each of neurofibroma, malignant peripheral nerve sheath tumour, angiosarcoma, alveolar cell sarcoma, extraosseous chondrosarcoma, extraosseous osteosarcoma and clear cell sarcoma of tendon sheath.

Presenting features included a discrete lump or diffuse swelling in 115 patients (95.8%). Pain was not a feature in 69 patients. 3 patients (2.5%) presented with pain alone and 2 patients (1.7%) with varicosities. 116 patients (96.7%) were referred to our unit as a possible soft tissue sarcoma. 4 patients were referred as suspected benign lesions requiring specialist assessment owing to size and location. 46 patients (38.3%) ignored their swelling, resulting in a delay to presentation to their local units. In only 13 patients was pain a feature. These were not considered to be true delayed referrals. 24 patients (20%) experienced a delayed referral to our unit. An alternative diagnosis was suggested in 7 patients by preliminary imaging investigations. A ‘Whoops procedure’ was performed in 14 patients. 3 patients were initially misdiagnosed as muscular injuries, with consequent conservative management resulting in delay.

Conclusion: Soft tissue sarcomas are relatively rare when considered alongside benign soft-tissue lesions. Pain is an infrequent feature, which may result in patients undervaluing their significance and delay their initial presentation to a doctor. Delayed referral is relatively common, although may not always be avoidable. Clinicians should maintain a high level of suspicion when dealing with soft-tissue lesions, with referral to a specialist centre whenever concern exists as to the nature of the lesion.

Purpose- To review the operative treatment of patients with chondrosarcoma of the pelvis and to study the long-term survival analysis of this cohort group.

Methods- A retrospective case study analysis was performed of patients with a diagnosis of chondrosarcoma of the pelvis treated in our hospital between 1990 and 2003. The operative notes and histopathological records were used along with the latest follow up letters.

Results- 54 cases (32 males and 22 females) with a mean age of 48.4 years ( 18–77) were identified. The aetiology was primary ( 38), recurrences ( 9) and secondaries ( 7).The sites in the pelvis were in the anatomical epicentre I(24), II(20) and III(10).The surgical procedures performed were local resection (28) , local resection and hip arthoplasty (6), hemipelvectomy (+ endoprosthesis) (16), hemipelvectomy (+ fibular strut graft) (2) and hindquater amputation (2).The histological grade was grade 1 (27), grade 2 (20) and grade 3(7). The complications rate was 24% – Wound revision (9%), dislocation (8%) and infection (7%). There was a 14-year cumulative survival rate of 46 % and 24 patients are surviving to date. The median follow up was 52 months.

The cumulative 14-year recurrence rate was 40% and the mean time to recurrence was 20.2 months.

Conclusion- There is an increased recurrence rate with epicentre I and III tumours and with those treated by local excision.

When managing malignant long bone tumours in skeletally immature patients it is desirable, after resection, to reconstruct with a prosthesis that can be lengthened at appropriate intervals to keep pace with growth of the contralateral side. In an attempt to avoid multiple surgical procedures to achieve such lengthening we have recently developed a prosthesis that can be lengthened non-invasively.

Purpose of study: To look at our early experience with the use of non-invasive growing femoral prostheses.

Methods: Between November 2002 and February 2004 the prosthesis was implanted in 6 patients (3 males and 3 females) with a diagnosis of osteosarcoma. The patients were aged between 9 and 14 years (mean 11.5 years) at the time of surgery. Patients were lengthened at appropriate intervals and the process was monitored with scanograms. The prosthesis contains a magnet that is connected to gears that drive the extending mechanism. The patients’ limb is placed into a coil and the principle of electromagnetic induction coupling is used to achieve lengthening. Total degree of lengthening to date was recorded for each patient together with the range of knee movement and any complications that occurred. Patients were functionally evaluated at their last follow-up visit using the Musculoskeletal Tumour Society (MSTS) Scoring System.

Results: To date patients have been lengthened by an average of 18mm (8–48mm). The mean amount of knee flexion is 125 degrees. The mean MSTS score is 18 (16–21). There have been two complications; one patient developed patella subluxation during the lengthening programme and one patient has required serial casting to treat a flexion deformity of 25 degrees.

Conclusions: We have been encouraged by our early results with this prosthesis and have been able to demonstrate that the technology works reliably in vivo. We are continuing to use this prosthesis in skeletally immature patients.

Purpose: The purpose of this study was to evaluate the results of custom-made endoprosthetic reconstruction for both tumourous and non-tumourous conditions around the elbow joint.

Methods and Results: 28 consecutive cases of endoprosthetic elbow reconstruction, performed between 1989 and 2003, were identified using the unit database. There were 12 males and 16 females, with a mean age of 48.9 years, (range 14–84). There were 16 cases of malignant tumour (10 primary, 6 secondary), 3 cases of benign tumour (one each of giant cell tumour, osteoblastoma and pigmented villonodular synovitis) and 10 non-oncological cases, (5 cases of fracture, 3 failed total elbow replacements and 1 infected synostosis). A distal humeral prosthesis was used in 16 patients, distal humeral and proximal ulna in 10 patients, proximal ulna with a humeral component in one patient and proximal radial replacement in one patient. Clinical and radiographic review of all available patients, including a functional assessment with The Toronto Extremity Salvage (TES) score was undertaken. The average follow-up was 54.9 months (range 5–144). 5 patients with malignancy died of their disease. One patient required amputation for local recurrence at 5 months. There were two revisions at 4 and 7 years for aseptic loosening of the humeral component. Six patients developed deep prosthetic infection at an average of 21 months (range 6–31), necessitating two-stage revision, of which one patient required subsequent excision arthroplasty. There were no cases of permanent nerve palsy. 18 patients (64.3%) were available for functional follow-up. Average flexion deformity was 33 degrees (7–80) and average flexion was 85 degrees (30–133). The mean TES score was 67.8 (range 36.6–96.6). The mean TES score following two-stage revision for infection, (available in 4/5 patients) was 73.9 (range 54.8–91.6).

Conclusion: Custom-made endoprosthetic reconstruction around the elbow joint is effective in a wide range of pathologies, allowing in most cases a reasonable level of function, even following two-stage revision for infection.

Purpose: Dedifferentiated chordomas are a rare and aggressive variant of chordoma. They usually occur in recurrences or following radiotherapy. We describe the rare occurrence of three cases arising de novo within conventional chordoma.

Methods and Results: 29 cases of histopathologically verified chordoma were identified from our unit database. From these, we identified three cases of primary dedifferentiated chordoma. The study group included three men, with an average age of 58.3 years (range 57–61). Presenting features were comparable and included lower back pain and rectal discomfort, with a mass palpable per rectum. A needle biopsy was undertaken in one patient, which demonstrated evidence of a pleomorphic spindle cell tumour without evidence of chordoma. Surgical management involved subtotal sacrectomy, with complete excision achieved in two cases. Histopathological examination confirmed dedifferentiated chordoma with varying amounts of sarcomatous elements in each case. Post-operative radiotherapy was administered in two patients and chemotherapy in one patient. Two patients died at 7 and 10 months following presentation with pulmonary metastases. The third patient remains well and alive at two years follow-up. This patient had a complete excision with post-operative radiotherapy, however histopathological examination revealed only a small focus of the dedifferentiated component.

Conclusions: Dedifferentiated chordoma is a fatal tumour, with metastases and death the likely outcome. Most cases in the literature and the two cases reported in this series, uphold this ominous prognosis. However this may not always hold true. Small areas of dedifferentiation within the chordoma tumour may carry a more favourable prognosis.

Clear cell sarcoma of soft tissues is a rare, poorly understood tumour with little written about it in peer reviewed literature. The aim of this paper is to present a consecutive series of patients treated at our institution.

All patients were staged using the system of the musculo-skeletal tumour society (MSTS). The aim of surgery was to achieve a wide excision. Adjuvant chemotherapy or radiotherapy was used in some patients depending on the margins, age and general health of the patient. Follow-up comprised clinical examination, magnetic resonance imaging (MRI) of the tumour bed and chest x-rays. Patients were seen 3 monthly for the first 2 years and then 6 monthly.

Between 1997 and 2003 14 patients were included. There were 5 males and 9 females with a mean age of 49 years (21–82). Mean follow-up was 42 months (1–84). Seven tumours occurred in the upper limb and 7 in the lower limb. Four patients were lymph node positive at presentation. The mean maximum diameter of the tumour was 5.6 cm (2–8). Ten patients were referred prior to excision but 4 patients had already undergone inadvertent excision biopsy elsewhere. Four patients developed local recurrence and 3 patients developed metastases. Seven patients remain disease free, 2 have no active disease, 1 is alive with disease and 4 have died of the disease.

The 2 year survival in this series is 71%. Poor prognostic factors include positive lymph nodes at diagnosis, maximum diameter of the tumour greater than 5cm and incomplete initial excision. It is important that these patients are treated early and that wide excision is achieved. We recommend early referral to a recognised musculo-skeletal tumour centre.

Aim: Sacral tumours are rare and can form a wide variety of differential diagnoses. We present a series of sacral tumour patients treated at a regional tumour centre; describing our experience of their management. Method: A retrospective study reviewing 76 sacral tumour patients, presenting to the Royal National Orthopaedic Hospital, Stanmore, from April 1976 to April 2002. The minimum follow-up period was 6 months. For each tumour type we looked at the incidence, diagnosis and outcome. Results: 69 of the lesions were primary bone tumours, 3 metastatic and 4 haematopoietic tumours. 33% of all tumours were chordomas. Osteosarcoma (10%), chondrosarcoma (8%) and giant cell tumour (8%) were the next most common. The commonest presenting symptom was lower back pain (64 cases). Good survival was demonstrated with chordomas and giant cell tumours. Osteosarcomas and chondrosarcomas had poor survival. Tissue diagnosis was accurately achieved with image-guided needle biopsy (61 cases). Magnetic resonance imaging (MRI) and computed tomography (CT) provided sufficient details for preoperative planning. Conclusion: The symptoms and signs of sacral tumours are non-specific and may lead to a misdiagnosis of degenerative disease of the spine. In our series chordomas account for only a third of all sacral tumours. Early diagnosis and staging are essential in order to determine definitive management and infl uence outcome. Surgery remains the most effective method for treating the malignant tumours.

Aim: Chordomas are relatively rare, malignant and strictly found in the midline. This study is to review our experience in the diagnosis, treatment and outcome of sacral chordomas. Method: A retrospective study reviewing 25 sacral chordoma patients treated at the Royal National Orthopaedic Hospital between August 1987 and April 2002, with a minimum follow-up of 6 months. Results: Of the 25 patients, 17 were male and 8 were female. The mean age at diagnosis was 61 years, and the mean duration of symptoms was 2 years. The commonest presenting symptom was lower back pain (20 cases). Three patients had inoperable tumours at the time of referral; the remaining 22 underwent surgical excision. A complete excision (based on microscopic examination) was achieved in11 cases, 2 of whom received adjuvant radiotherapy. Of the11 who had an incomplete excision 8 received adjuvant radiotherapy. Complete excision extended the mean disease free period to2.92 years, compared to 0.67 years following incomplete excision. The disease free period following an incomplete excision was extended from a mean of 0.67 years to 2.82 years with radiotherapy. 10 patients had postoperative neurological complications. Conclusion: We believe that the aim of surgical resection should be a microscopically complete excision margin, having documented an increased time to recurrence in patients in whom this has been achieved, compared to those treated with an incomplete excision. Radiation therapy should be given after an incomplete excision as we have shown that it lengthens the disease free interval in these cases.

Aims: Damage to articular hyaline cartilage may predispose to earlyonset osteoarthritis. Hyaline cartilage has not been shown to spontaneously regenerate and previous methods of stimulating repair have often yielded þbrocartilage. Autologous chondrocyte implantation (ACI) offers the potential for hyaline cartilage repair. Methods: A prospective study of 31 patients undergoing ACI using the chondrogide membrane. Patients were assessed clinically using validated knee scores pre-operatively and post-operatively at yearly intervals. Arthroscopy was carried out at one year post implantation and a biopsy of the transplanted area was sent for histological examination. Results: 32 knees (including 2 bilateral) were reviewed clinically at one year, and 15 were reviewed at 2 years. 33 defects (including 2 defects in one knee) were assessed arthroscopically at one year. Only one repair showed hypertrophy at one-year arthroscopy, and 8 had poor integration. Hyaline-like cartilage was demonstrated in 70% of the repairs. Patients showed improvement in the Verbal Numerical Pain scores and in the Lysholm and Gillquist score. Conclusions: In our series, the use of chondrogide membrane shows a low incidence of hypertrophy when compared to periosteum. Improvement in knee scores was statistically signiþcant at one and two years.

Mesenchymal stem cells (MSCs) are pluripotential cells present in marrow, which have the ability to differentiate into osteoblasts, chrondrocytes and adipocytes. Potential skeletal tissue engineering uses include healing bone defects, spinal fusion and revision arthoplasty surgery. A means of storing viable mesenchymal stem cells is necessary in order for these cells to be readily available for clinical use. The aim of this study was to determine whether cryopreservation has any effect on the osteogenic potential of human bone marrow derived MSCs.

Five normal iliac crest bone marrow aspirates were obtained following informed consent from patients. Each aspirate was divided into two equal samples. Ficoll-separation was used to isolate the MSCs. The fresh MSCs from one sample were cryopreserved, while the other was cultured as a control population. To assess the osteogenic potential of the MSCs after cryopreservation a sample of cells from each population was cultured with osteogenic supplements and the increase in alkaline phosphatase (ALP) and osteocalcin production was compared.

Cryopreservation was not observed to effect the primary cultures of MSCs, which became confluent after a similar period in culture (12–14 days), forming colonies with recognized MSCs morphology. The expression of ALP and osteocalcin after stimulating the MSCs to differentiate with osteogenic supplements, was not significantly altered by the cryopreservation process (P> 0.05).

In conclusion MSCs obtained from fresh human bone marrow aspirates can be cryopreserved without compromise to their proliferation rate or osteogenic potential, confirming that this is a useful means of storing viable cells for future clinical use.

Osteoblast progenitor cells can be isolated from human bone marrow and on an appropriate carrier following differentiation into osteoblasts a bone block could be formed. This supply of autologous, osteoinductive bone graft substitute would have significant implications for clinical use. The aim of the study was to assess whether osteoblast progenitor cells isolated from human bone marrow, seeded onto porous hydroxyapatite (HA) blocks adhere, proliferate and differentiate into osteoblasts under the influence of HA alone.

After informed consent, bone marrow was aspirated from the iliac crest of 8 patients. The osteoblast progenitor cells were separated from the haematological cells and cultured in vitro. Evidence for the osteoblast progenitor nature of the cells was obtained by adding osteogenic supplements: dexamethasone, ascorbic acid and b-glycophosphate, and comparing alkaline phosphatase (ALP) and osteocalcin expression with that of unstimulated cells. Undifferentiated osteoblast progenitor cells were seeded at a density of 2x10 ⁶ cells/porous HA cylindrical block (8 x 8 x10 mm). The cell adhesion to the HA was observed, and proliferation and ALP expression was measured over 15 days.

In monolayer culture the isolated bone marrow cells were morphologically identified as mesenchymal stem cells. When osteogenic supplements were added the phenotype became consistent with the morphology of osteoblastic cells, and the ALP expression was significantly higher (P< 0.05) after 5 days in culture compared with cells that had not been stimulated to differentiate.

On the HA osteoblast progenitor cells were adherent and became more osteoblastic, being separated from the HA surface by an osteoid matrix layer on electron microscopy. The ALP expression by these cells increased significantly (P< 0.05) over the 15 day culture period.

Bone marrow contains mesenchymal stem cells with osteogenic potential that are known as osteoblast progenitor cells. In this study we have shown that osteoblast progenitor cells can be isolated from human bone marrow and will adhere to and proliferate on HA blocks in vitro, and differentiate into osteoblasts spontaneously under the influence of the HA scaffold. These constructs could be used as osteoinductive bone grafts.

To assess the clinical features, development of metastases, and survival rate of patients with local recurrence after the resection of osteosarcoma in a large series.

Five hundred and thirty (530) patients with high-grade osteosarcoma were treated between 1989 and 1998. Fifty-four patients (10%) developed local recurrence after resection and adjuvant chemotherapy. There were 38 men and 16 women with a mean age of 19 years (range 6–50). The mean follow up was 39 months (range 7–120 months). Forty-three patients (79%) had clear resection margins microscopically, while in 8 patients (15%) microscopic tumour was found at the resection margin, and contaminated excision was performed in 3 patients. Histological response was category 1 in 24% of the patients, and category 2 in 76%. Clinical features, treatment, and prognosis were analyzed. Survival rates were examined using Kaplan-Meier Analysis.

The average interval between the first resection and local recurrence was 15 months (range 2–109 months). Forty-one patients (76%) had local recurrence in deep soft tissue, 7 in bone, and 6 in subcutaneous tissue. Twenty-six patients (49%) had lung metastasis at the time of local recurrence, while 21 patients (38%) developed it later. Thirty patients (57%) were treated with resection of the recurrent lesion and 18 (32%) were treated with amputation. 1-, 3-, and 5-year survival rates after local recurrence were 0.57, 0.38, and 0.22 respectively.

87% of patients with local recurrence developed metastases either concurrently or at a later date. Immediate amputation did achieve local tumor control. However, the survival rate was not statistically higher.

100 pre-operative and post-operative knee and function scores were analysed to assess whether a low pre-operative score was related to a poorer outcome, ie, are we operating too late? A two tailed student “t” test was performed showing that a pre-operative “function “ score of less than 30, resulted in a lower post-operative “function” score and the difference was statistically significant. These patients also showed the greatest improvement in scores and were the most satisfied with surgery. However, a low pre-operative “knee” score could not be related to a low post-operative “knee” score. Patients who had either a “knee” or “function” score of greater than 60 made no statistically significant improvement in either score. In conclusion, the pre-operative “knee” score is not a reliable indicator for when to perform surgery. However, the “pre-operative “ function score should be given more credence, along with clinical judgement, as it would appear that operating too late adversely affects the functional outcome of total knee arthroplasty.

Chondrosarcoma is the second most common bone tumour and occurs in the third to sixth decades of life. It most commonly arises in the pelvis and proximal femur.

We performed a clinical, operative and histological review of all patients seen at our unit with chondro-sarcoma of the pelvis over a ten-year period. We iden-tified 36 cases of chondrosarcoma of the pelvis and a retrospective analysis of cases was performed examining the rate of tumour recurrence and mortality rate with respect to tumour grade, anatomical site and type of surgery performed.

25 patients had a primary tumour diagnosed, 6 tumours were secondary to MHE and the remaining 5 were recurrent tumours. The tumours were situated in the acetabulum (14), the pubic / ischial rami (7), and the iliac wing (15). Surgical procedures included wide local excision (18), wide local excision and total hip arthroplasty (4), hemipelvectomy and endoprosthesis (13), and hind quarter amputation (1). The median follow up period was 48 months.

10 year cumulative survival rate was 40% and poor survival was associated with iliac tumours and higher grade tumours. Mean time to recurrence was 18.5 months and cumulative 10 year recurrence rates were 44%. Increased recurrence was associated with iliac and rami tumours and those excised by local resection alone. High tumour grade was not associated with increased recurrence in our study. The overall surgical complication rate of the operative procedures was 27%. These included dislocation and infection of prosthesis. Conclusions: This disease continues to be a surgical challenge with a clear association between more radical surgery and low tumour recurrence rates. However this must be balanced against the potentially devastating complications associated with this major reconstructive surgery.

65 patients over the age of 80 years, who underwent a total knee arthroplasty between 1989 and 1994, were retrospectively reviewed, by means of questionnaire, phone call, clinical and radiological examination.Notes were reviewed for pre-existing medical conditions, pre-operative and post-operative Knee Society “Knee” and “Function” scores. They were then compared with 65 randomly selected patients in a different age group, 70 years and under.56 octogenarians were alive at 5 years and 50 available for full review.

Elderly patients had more pre-existing medical conditions, with hypertension a ubiquitous diagnosis, required a longer in patient stay and more social services input before discharge, than the younger age groups. All patients in the elderly group suffered from osteoarthritis, unlike the younger age groups. Valgus deformity of the knees was only seen in the younger cohort. Previous surgery was more common in the octogenarians, with more octogenarians having undergone a tibial osteotomy and more youngsters undergoing arthroscopy. A reflection of changing surgical practice.

“Knee” Scores were not significantly different between the age groups. However, the “function “ scores pre-operatively, were significantly lower in the over 80s and they made a more significant post-operative gain. Post-operatively, elderly male patients were more likely to go into retention post-operatively, than female patients and males in the younger age group.

None of the prostheses had required revision in the elderly age group and only 5 patients had died since the surgery. None of the deaths were related to the surgery.

We recommend pre-operative catheterisation of octogenarian patients, especially those with a history of prostatism. There would appear to be from this review no indication for denying elderly patients an arthroplasty on the basis of age.

Primary bone tumours are rare and account for only 1% of cancer deaths. The commonest area for tumour occurrence is around the knee. With the advent of chemotherapy and improved survivorship of patients with osteosarcoma and Ewings of the extremities, excision of the primary lesion and reconstruction has become both a viable and routine option in specialist centres.

The surgical options include; excision alone, or excision and reconstruction with Autograft or allograft, or using massive prostheses to fill the defect.

In the UK, we have developed and used massive endoprostheses to fill the defect made following tumour excision and I would like to report our experience.

The first report of the use of massive endoprostheses was by Seddon & Scales in 1949 at The Royal National Orthopaedic Hospital, Stanmore. Since then both the number primary and revision procedures has continued to grow on a yearly basis. In the year 2000 we carried out 95 primary massive endoprosthetic replacements and 27 revisions.

In terms of functional score (Musculoskeletal Tumour Soc), following excision of tumours of the lower limb including excision of the affected joint, results are superior in those patients who undergo reconstruction using an endoprostheses (87%), as opposed to reconstructions using either osteoarticular allograft (68%), or rotationplasty (85%).

The long term survivorship of prosthetic replacement varies enormously between the upper and lower limbs due to the different forces acting upon them, indeed revision for aseptic loosening in the upper limb is rare.

In the lower extremity the probability of survivor-ship of a cemented proximal femoral replacement at ten years is 93.8%, whilst those for the distal femur or proximal tibia using a fixed hinge (Stanmore Mk4) are 67.4% and 58% respectively. The two factors that have a huge bearing on this are; the age of the patient and the amount of the diaphysis of the long bone resected.

To try and improve the long-term fixation of implants we have used porous coated collars at the prosthesis bone interface. These were first used in 1988, however subsequent retrieval specimens showed only fibrous tissue ingrowth although initial x-rays were thought to be encouraging.

Hydroxyapatite coated collars were first used in 1989 and have become standard use in all endoprosthetic replacement since. Indeed, retrieval specimens have revealed good bone ingrowth and no delamination of the HA.

Another huge advance has been the introduction in 1991 of the rotating hinge for implants of the distal femur and proximal tibia.

Subsequent studies have shown a significant reduction in aseptic loosening in distal femoral replacements which have both an HA collar and incorporate a rotating hinge.

Since 191 we have also developed fully uncemented endoprosthetic replacements for our younger patients with a satisfactory outcome. These results will be discussed.

In the future we hope to make further developments in the area of the non-invasive growing prosthesis, and soft tissue attachment around prosthesis especially those of the proximal humerus and the proximal femur.

The aim of this study is to evaluate the early results of gleno-humeral reconstruction after tumour excision with a new design of endoprosthesis.

The prosthesis is a fixed fulcrum gleno-humeral replacement consisting of a hydroxyapatite (HA) coated glenoid component with a polyethylene liner and a cemented stem with HA coated collar. Between 1997 and 2000 we inserted the prosthesis into 15 patients with primary bone tumours of the proximal humerus. There were nine males and six females with a mean age of 38 years (range: 8–71 years). Twelve stems were cemented and three uncemented. Two skeletally immature patients had an extendible stem inserted, one subsequently having a successful lengthening procedure. The mean follow-up was 28 months (range: 12–41 years). Functional outcome was assessed using the Musculoskeletal Tumour Society (MTS) scoring system.

There were two early dislocations and one superficial wound infection. Three patients died of their disease and one underwent forequarter amputation for local recurrence. The remaining eleven had satisfactory functional outcomes with a mean MTS score of 81%. Radiologically there has been no evidence of early loosening. Microscopic analysis of the components in the amputated arm showed excellent osseointegration around the HA coated components.