We have studied the relationship between metal ion levels and lymphocyte counts in patients with metal-on-metal hip resurfacings. Peripheral blood samples were analysed for lymphocyte subtypes and whole blood cobalt and chromium ion levels in 68 patients (34 with metal-on-metal hip resurfacings and 34 with standard metal-on-polyethylene total hip replacements). All hip components were radiologically well-fixed and the patients were asymptomatic. Cobalt and chromium levels were significantly elevated in the patients with metal-on-metal hip resurfacings, compared with the patients with standard metal-on-polyethylene designs (p < 0.0001). There was a statistically significant decrease in the level of CD8⁺ cells (T-cytotoxic/suppressor) (p = 0.005) in the metal-on-metal hip resurfacing group. A threshold level of blood cobalt and chromium ions was associated with reduced CD8⁺ T-cell counts. We have no evidence that our patients suffered as a result of this reduced level of CD8⁺ T-cells.

We developed a new porous scaffold made from a synthetic polymer, poly(DL-lactide-co-glycolide) (PLG), and evaluated its use in the repair of cartilage. Osteochondral defects made on the femoral trochlear of rabbits were treated by transplantation of the PLG scaffold, examined histologically and compared with an untreated control group.

Fibrous tissue was initially organised in an arcade array with poor cellularity at the articular surface of the scaffold. The tissue regenerated to cartilage at the articular surface. In the subchondral area, new bone formed and the scaffold was absorbed. The histological scores were significantly higher in the defects treated by the scaffold than in the control group (p < 0.05).

Our findings suggest that in an animal model the new porous PLG scaffold is effective for repairing full-thickness osteochondral defects without cultured cells and growth factors.

Conventional amputation prostheses rely on the attachment of the socket to the stump, which may lead to soft-tissue complications. Intraosseous transcutaneous amputation prostheses (ITAPs) allow direct loading of the skeleton, but their success is limited by infection resulting from breaching of the skin at the interface with the implant. Keratinocytes provide the skin’s primary barrier function, while hemidesmosomes mediate their attachment to natural ITAP analogues. Keratinocytes must attach directly to the surface of the implant. We have assessed the proliferation, morphology and attachment of keratinocytes to four titaniumalloy surfaces in order to determine the optimal topography in vitro. We used immunolocalisation of adhesion complex components, scanning electron microscopy and transmission electron microscopy to assess cell parameters.

We have shown that the proliferation, morphology and attachment of keratinocytes are affected by the surface topography of the biomaterials used to support their growth. Smoother surfaces improved adhesion. We postulate that a smooth topography at the point of epithelium-ITAP contact could increase attachment in vivo, producing an effective barrier of infection.

We have undertaken a prospective, randomised study to compare conservation of acetabular bone after total hip replacement and resurfacing arthroplasty of the hip. We randomly assigned 210 hips to one of the two treatment groups. Uncemented, press-fit acetabular components were used for both.

No significant difference was found in the mean diameter of acetabular implant inserted in the groups (54.74 mm for total hip replacement and 54.90 mm for resurfacing arthroplasty). In seven resurfacing procedures (6.8%), the surgeon used a larger size of component in order to match the corresponding diameter of the femoral component.

With resurfacing arthroplasty, conservation of bone is clearly advantageous on the femoral side. Our study has shown that, with a specific design of acetabular implant and by following a careful surgical technique, removal of bone on the acetabular side is comparable with that of total hip replacement.

We have investigated the significance of the method of treatment on the oncological and functional outcomes and on the complications in 184 patients with soft-tissue sarcomas of the adductor compartment managed at three international centres. The overall survival at five years was 65% and was related to the grade at diagnosis and the size of the tumour. There was no difference in overall survival between the three centres. There was, however, a significant difference in local control with a rate of 28% in Centre 1 compared with 10% in Centre 2 and 5% in Centre 3.

The overall mean functional score using the Toronto Extremity Salvage Score in 70 patients was 77% but was significantly worse in patients with wound complications or high-grade tumours. The scores were not affected by the timing of radiotherapy or the use of muscle flaps.

This large series of soft-tissue sarcomas of the adductor compartment has shown that factors influencing survival do not vary across the international boundaries studied, but that methods of treatment affect complications, local recurrence and function.

Despite increasing scientific investigation, the best method for preventing post-operative deep-vein thrombosis remains unclear. In the wake of the publication of the Pulmonary Embolism Prevention trial and the Scottish Intercollegiate Guidelines Network (SIGN) on the prevention of thromboembolism, we felt that it was timely to survey current thromboprophylactic practices. Questionnaires were sent to all consultants on the register of the British Orthopaedic Association. The rate of response was 62%. The survey showed a dramatic change in practice towards the use of chemoprophylaxis since the review by Morris and Mitchell in 1976. We found that there was a greater uniformity of opinion and prescribing practices in Scotland, consistent with the SIGN guidelines, than in the rest of the UK. We argue in favour of the use of such documents which are based on a qualitative review of current scientific literature.

The Oxford hip and knee scores are used to measure the outcome after primary total hip and knee replacement. We propose a new layout for the instrument in which patients are always asked about both limbs. In addition, we have defined an alternative scoring method which accounts for missing data. Over a period of 4.5 years, 4086 (1423 patients) and 5708 (1458 patients) questionnaires were completed for hips and knees, respectively. The hip score had a pre-operative median of 70.8 (interquartile range (IQR) 58.3 to 81.2) decreasing to 20.8 (IQR 10.4 to 35.4) after one year. The knee score had a pre-operative median of 68.8 (IQR 56.2 to 79.2) decreasing to 29.2 (IQR 14.6 to 45.8). There was no further significant change in either score after one year. As a result of the data analysis, we suggest that the score percentiles can be used as a standard for auditing patients before and after operation.