Hip Conversion: Don't Promise Too Much

Recognized long-term problems associated with hip fusion include lower back pain, ipsilateral knee instability, contralateral patellofemoral pain, and contralateral hip pain. However, one of the major concerns in converting a hip arthrodesis to total hip arthroplasty (THA) is residual limp, due to insufficient abductor muscle strength. A series of patients who had undergone conversion of a hip fusion to THA were assessed postoperatively, in regards the Harris hip score (HHS), and the degree of limp (absent, mild, or severe/Trendelenburg positive). Patients were asked to evaluate their overall satisfaction with the procedure. The cohort included 24 patients and 25 hips. Mean age of the patients was 50.5 years (27-72), with a mean length of time from initial fusion of 19 years (5-40). The average follow-up of the patient was 8.6 years (2-17). Intraoperative complications included 2 calcar splits, and 3 femoral shaft fractures requiring an intraoperative switch to a long-stem implant. At latest follow-up, limp was absent in 20%, mild in 12%, and severe in 68%. Postoperative HHS was excellent in 28%, good in 32%, fair in 16%, and poor in 24%. Four patients required a cane to walk. All patients indicated they were overall satisfied with the procedure, and would consent to undergoing the procedure again. Although patient satisfaction rates are high after conversion of a hip fusion to THA, the incidence of postoperative limp is also high (80%), and only 60% have good or excellent postoperative HHSs.