Total hip arthroplasty after previous arthrodesis has been associated with increased complications and decreased survivorship of the prosthesis. We evaluated pain, function, and the factors influencing survivorship of total hip arthroplasties after previous arthrodesis between 1985 and 2000 and compared these results with those obtained in prior years with the same procedure and in the same institution. We retrospectively reviewed 30 patients who had previous spontaneous or surgical arthrodesis. The minimum followup was 2 years (mean, 10.4 years; range 2-20.5 years). Seven failures were identified (23%). The overall survival free of failure was 86% at 5 years and 75% at 10 years. At last followup, 27 of the 30 patients (91%) had no or slight pain, 26 (87%) had a limp, and 18 (61%) needed a gait aid. Surgical arthrodesis, age younger than 50 years at the time of arthroplasty, and length of arthrodesis less than 30 years independently predicted failure. Conversion of arthrodesis to hip arthroplasty reliably decreases pain and improves function, but many patients will limp and require a gait aid. Our outcomes were similar to those after revision rather than after primary hip arthroplasty.

Some surgeons have suggested that a minimally invasive two-incision approach allows total hip arthroplasty to be done without cutting or damaging any muscle or tendon. To our knowledge that claim has not been supported by any published clinical or basic science data. Our purpose in doing this study was to quantify the extent and location of damage to the abductor and external rotator muscles and tendons after two-incision and mini-posterior total hip arthroplasty. Ten cadavers (20 hips) were studied. In each cadaver one hip randomly was assigned to the two-incision group and the contralateral hip was assigned to the mini-posterior group. After inserting the total hip arthroplasty components the muscle damage was assessed using a technique described previously. Damage to the muscle of the gluteus medius and gluteus minimus was substantially greater with the two-incision technique than with the mini-posterior technique. Every two-incision total hip replacement caused measurable damage to the abductors, the external rotators, or both. Every mini-posterior hip replacement caused the external rotators to detach during the exposure and had additional measurable damage to the abductor muscles and tendon. We do not support the contention that a two-incision total hip arthroplasty is done without cutting muscle or tendon. None of the two-incision hip replacements were done without cutting, reaming, or damaging the gluteus medius or gluteus minimus muscle or external rotators.