METAL ON METAL-SURFACE REPLACEMENT OF THE HIP - TECHNIQUE, FIXATION, AND EARLY RESULTS

High volumetric wear of polyethylene plays a central role in periprost hetic bone resorption and the failure of metal on polyethylene total h ip resurfacing prostheses. An assessment of technique, initial fixatio n, and the early results of 21 hips in 19 patients implanted with a me tal on metal bearing total hip resurfacing prosthesis, 4 all cementles s Wagner prostheses and 17 all cemented McMinn prostheses, is presente d. 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 satisfa ctory in all 21 hips and there were no femoral neck notches or fractur es. All 4 cementless Wagner acetabular components appear to be osseoin tegrated with stable interfaces. The cemented McMinn acetabular compon ents, however, have shown progressive cement bone interface radiolucen cies in 12 hips. This preliminary experience underscores the importanc e of obtaining secure initial fixation. There have been no problems di rectly attributable to the metal on metal bearing but the authors will continue to follow these hips and evaluate their performance. The met al on metal hip surface replacement procedure is in evolution. This on -going experience will help guide total hip surface replacement compon ent design and implantation techniques.