The effect of surface coating of femoral prostheses implanted without cement: a 2- to 4-year follow-up study.

A randomized, concurrently controlled, prospective, single-blinded, multicenter study was done to evaluate the effect of proximal surface coating of a femoral prosthesis on clinical and radiographic results of cementless total hip arthroplasty (THA). The Profile femoral prosthesis (DePuy, Warsaw, IN), an anatomic titanium alloy stem, was used in one of three configurations: (1) smooth, (2) porous coated, or (3) hydroxyapatite (HA) coated. Ninety-one cases were enrolled in the study, with seven cases lost to follow-up and 79 cases available for clinical review with 24- to 48-month follow-up. The study shows that HA-coated stems performed as well, if not better than, porous-coated or smooth stems. Results show HA-costed stems with statistically superior total Harris hip scores (microHA = 96.0) than smooth stems (microS = 85.1) (Student's t-test, P = 0.004). This was primarily due to differences between the functional score of the two groups (microHA - 31.6; microS = 27.9, P = 0.003). Porous-coated stems were intermediate in performance (microPC = 89.8), with hip scores that were statistically indistinguishable from both smooth and HA-coated stems. Our data support the hypothesis that clinical differences exist and are attributable to the type of surface coating used for the cementless femoral components in THA.