High Complication Rate After Revision of Large-head Metal-on-metal Total Hip Arthroplasty

Previous studies have indicated poor outcomes in patients having revision of hip resurfacing resulting from adverse local tissue reaction and pseudotumor. We reviewed all patients at our institution who had revision of failed large-head metal-on-metal total hip arthroplasty to determine (1) complications including reoperations; (2) radiologic outcomes; and (3) changes in serum ions after removal of the metal bearing. From our research database, we identified 32 hips in 30 patients. Revisions were performed through a posterior approach; 17 were performed with a titanium fiber-metal shell and 15 with a porous tantalum shell, and 29 of the 32 revisions were performed with large (36- or 40-mm) femoral heads. Clinical records were reviewed and interviews conducted in the clinic or by telephone. Nineteen hips had a pre- or intraoperative diagnosis of adverse local tissue reaction, three had deep infection, and 10 had loosening of the acetabular component. Major complications occurred in 12 (38%) of the 32 revisions. Nine of 32 hips (28%) sustained dislocations. Four of 17 fiber-metal acetabular components failed to ingrow; none of the porous tantalum cups failed to ingrow. Seven repeat revisions were performed in six patients: three for acetabular loosening, three for recurrent dislocation, and one for recurrent adverse local tissue reaction. The mean WOMAC pain score was 78 of 100 and the function score was 83 of 100. Metal ion levels decreased after revision in most patients. As a result of the high rate of failure of the fiber metal cups, we have elected to use an enhanced fixation surface with a high-porosity cup for revision of these cases. We observed a high rate of dislocation despite the use of 36-mm and 40-mm heads. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.