Hip resurfacing arthroplasty: the evolution of contemporary designs.

Metal-on-metal hip resurfacing is considered by many as the most significant recent development in hip arthroplasty. It preserves proximal femoral bone stock, optimizes stress transfer to the proximal femur, and offers inherent stability and optimal range of movement. The early results of hip resurfacing in the 1970s and 1980s were poor and the procedure was largely abandoned by the mid-1980s. The expectation that these prostheses would be easy to revise was not often fulfilled. The large diameter of the articulation combined with thin polyethylene cups or liners resulted in accelerated wear and the production of large volumes of biologically active particulate debris, leading to bone loss and implant loosening. Failure has been attributed to other factors, mainly avascular necrosis of the femoral head. However, this concern has not been confirmed by retrieval studies. The failure of early hip resurfacings was essentially a consequence of the use of inappropriate materials, poor implant design, inadequate instrumentation, and crude surgical technique. It was not an inherent problem with the procedure itself. The renaissance of metal-on-metal articulations for total hip arthroplasty enabled the introduction of new hip resurfacings and most of the major implant manufacturers have already introduced such systems. Early results are encouraging and complications commonly seen in the 1970s and 1980s, such as early implant loosening and femoral neck fracture, now appear to be rare. Whilst early results should be regarded with caution, modern metal-on-metal hip resurfacing potentially offers the ultimate bone preservation and restoration of function in appropriately selected young patients.

Total hip arthroplasty for developmental hip dysplasia.

We reviewed 38 hip replacements in 33 female patients (mean age 55.3 years) with developmental hip dysplasia. One patient had died and the remaining 32 patients (36 hips) had a mean follow-up of 12.2 years (range 8-19 years). All hips were replaced using the Müller cemented implant, and in 32 hips bulk femoral head autograft was used. In 33 hips the socket was reconstructed at the level of the true acetabulum. Complications included one intra-operative femoral fracture and two early dislocations. Correction of leg length discrepancy was possible in 30 patients. The post-operative mean modified Merle d'Aubigne and Postel scores for pain, movement and walking were 5.9, 5, and 5.3 respectively. One cup was revised due to aseptic loosening at ten years. All grafts united, but minor graft resorption was noticed in 24 hips, moderate in 2 hips and major in 1 hip.

The development of the DuromTM metal-on-metal hip resurfacing.

The poor results of conventional total hip replacement in young and active patients have led to a renewed interest in alternative interventions and bearing material combinations. Con-temporary metal-on-metal resurfacing of the hip has emerged as an attractive option. This procedure utilises a low wear producing bearing which minimises the risk of periprosthetic osteolysis, preserves femoral bone stock should subsequent procedures become necessary, and, due to the increased stability and range of motion, allows the rapid resumption of an active lifestyle. We describe the development of the DuromTM metal-on-metal hip resurfacing and report the preliminary results of the first 100 consecutive cases.