[Development of hip resurfacing].

Total hip replacement in its current form has proved to be very effective in late middle-aged and elderly patients. However, in the younger patient population the survival rate is still not acceptable. Since the very beginning of hip resurfacing, the procedure has been advocated as an attractive concept to preserve proximal femoral bone stock. Furthermore, it is supposed to optimize stress transfer to the proximal femur and because of the large head size improves joint stability and range of motion. The failure of previous resurfacings has been described to be due to inappropriate materials, poor design, and poor instrumentation and not as an inherent problem of the procedure itself. Progress in materials and material design (metal-on-metal) as well in experience in surgical technique seem to have overcome formerly experienced difficulties. This means a lower rate of femoral neck fractures and aseptic loosenings, at least in the short-term and midterm follow-up of patients with good function. High manufacturing standards are required to consistently produce low-wear metal-on-metal bearings and it is still unclear whether high metal ion levels, which occur in all patients with metal-on-metal hip replacements, have any biologic effect. At least so far there is no evidence of any negative clinical effect in this regard. Only long-term results in a higher number of patients and a more widespread use of this procedure will tell whether early success is durable or it is just a bone-preserving, intermittent step before conventional total hip replacement.