Salvage of a Recurrently Dislocating Total Hip Prosthesis with Use of a Constrained Acetabular Component. A Retrospective Analysis of Fifty-six Cases*

Fifty-six constrained acetabular components were placed, between April 1988 and February 1993, in fifty-five patients who had had recurrent dislocations (average, six dislocations; range, two to twenty dislocations) of the femoral component after a previous total hip arthroplasty. All patients had additional factors contributing to the instability of the implant, including absence or disruption of the abductor mechanism, poor health, mental retardation, confusion, and Alzheimer disease. One patient was lost to follow-up. The remaining patients were followed clinically for a minimum of three years (average, sixty-four months; range, thirty-seven to ninety-seven months) or until the time of death. During the follow-up interval, only two (4 per cent) of the fifty-five patients had a subsequent dislocation. The use of this type of component should be considered for patients who have recurrent dislocation if other treatment modalities are unlikely to be effective.