Mid-term results of a polyethylene-free metal-on-metal articulation.

Beginning in December 1995, 193 patients (195 hips) were enrolled into this prospective, randomized, controlled multicenter investigational device exemption study. Ninety-eight patients (99 hips) with 46 polyethylene liners and 53 metal liners had minimum 5-year follow-up (mean, 5.7 years). Average follow-up, Harris hip score improvement, and radiographic analysis were not statistically different between groups. No stress shielding or osteolysis was observed in either group. Three polyethylene liners and no metal liners had acetabular radiolucencies <1 mm in 1 or more zones. There have been no device-related complications, no acetabular revisions performed, and none pending in either group. Based on these mid-term results, the authors conclude that a metal-on-metal articulation represents a viable alternative in young, high-demand, active patients.