Dislocations following arthroplasties of the hip. Incidence, prevention, and treatment.

Three methods of avoiding postoperative prosthetic dislocation following total or bipolar hip arthroplasty are described; each approach is recommended for a specific population. The anterior surgical approach was utilized for bipolar hip endoprosthetic arthroplasty in 62 minimal or bed-to-chair ambulators with established flexion contractures about the hip. Two of these patients subsequently experienced a prosthetic dislocation, one of which was secondary to infection. An additional 98 patients who underwent arthroplasty using the posterior approach wore a knee immobilizer postoperatively, without incidence of prosthetic dislocation. A modification of Wilke boot casting was utilized for four patients following reduction of a dislocated hip prosthesis. The cast consisted of a short cylinder cast on the affected extremity connected by a cross bar to a short leg cast on the contralateral leg. The casts controlled rotation, were well tolerated, and resulted in no redislocations. We therefore recommend the anterior approach in minimal ambulatory patients who are to undergo total bipolar hip arthroplasty. When the posterior approach is used in hip replacement procedures, we have found that postoperative use of a knee immobilizer helps prevent dislocation. Following reduction of a dislocated hip prosthesis, a modification of the Wilke boot cast that does not immobilize the affected ankle can be used.