Dislocation after revision of hemiarthroplasty to total hip replacement.

Over a 3-year period, nine hemiarthroplasties were revised to total hip arthroplasty. The hemiarthroplasties were all performed for an original diagnosis of subcapital fracture, and the revisions were for a variety of indications including instability, loosening and acetabular erosion. Four of the revised prostheses subsequently dislocated, and one has recurrent subluxation. This dislocation rate of 50% is higher than previously reported. Factors contributing to this are discussed. These include: previous strokes, advanced age, difficulty complying with instructions, and a hip capsule not contracted by osteoarthritis. Preventative factors are discussed. It is imperative to treat this group of patients differently from those having other hip arthroplasties, and to consider prophylactic bracing post-operatively. The capsule or pseudo-capsule should be preserved wherever possible.