Metal on metal surface replacement of the hip. Technique, fixation, and early results

High volumetric wear of polyethylene plays a central role in periprosthetic bone resorption and the failure of metal on polyethylene total hip resurfacing prostheses. An assessment of technique, initial fixation, and the early results of 21 hips in 19 patients implanted with a metal on metal bearing total hip resurfacing prosthesis, 4 all cementless Wagner prostheses and 17 all cemented McMinn prostheses, is presented. Pain relief was equal to conventional total hip replacement with a better functional result with an average followup of 16 months (range, 10-25 months). The femoral component position and fixation is satisfactory in all 21 hips and there were no femoral neck notches or fractures. All 4 cementless Wagner acetabular components appear to be osseointegrated with stable interfaces. The cemented McMinn acetabular components, however, have shown progressive cement bone interface radiolucencies in 12 hips. This preliminary experience underscores the importance of obtaining secure initial fixation. There have been no problems directly attributable to the metal on metal bearing but the authors will continue to follow these hips and evaluate their performance. The metal on metal hip surface replacement procedure is in evolution. This ongoing experience will help guide total hip surface replacement component design and implantation techniques.