Present state of metal-on-metal hybrid hip resurfacing.

Bone conservation and preservation, joint stability, and low wear of the large metal-on-metal resurfacing bearings have been convincingly demonstrated in the current literature. The clinical results of 600 MM Hybrid Conserve Plus Resurfacing in 519 patients with an average follow-up of 6.9 years (range, 4.0-10.4 years) have been excellent. The average age was 48.9 years, 74% of the patients were male, and the study included all etiologies of the young with arthritis. The complication rates other than dislocation and fracture of the femoral neck are comparable between resurfacing and conventional total hip replacement. The incidence of femoral neck fracture is low (1.2% worldwide) with less than 0.6% in this series and none occurring in the last 5 years due to proper patient selection and improved surgical technique. Component loosening after metal-on-metal resurfacing has been significantly reduced and acetabular component loosening is uncommon and has not happened in this series. Femoral bone preparation and optimal cementing techniques are paramount to prevention of femoral loosening. Clearance between the cylindrically reamed part of the head and the component varies in different designs, and the surgeon must note the need for different cementing strategies for different recommended clearances. The learning curve of a surgeon undertaking resurfacing can be greatly reduced by observation and hands-on training in specialized centers with surgeons experienced in resurfacing.