Recurrent instability after total hip arthroplasty: beware of subtle component malpositioning.

Most patients exhibiting instability after total hip arthroplasty can be treated nonoperatively. However, instability may become recurrent and require surgical intervention. Abductor insufficiency and component malpositioning constitute two of the most important causes of recurrent instability, although the exact cause may not be identifiable in some patients. There is relative scarcity of reports in the literature regarding the outcome of surgical intervention for recurrent instability; however, it is known that surgical intervention is likely to have a better outcome in patients for whom the cause of recurrent instability can be identified. We hypothesized that component malpositioning, which may be subtle in some cases, is the cause of recurrent instability for many patients. The outcomes of revision arthroplasty in 93 patients who were treated at our institution for recurrent instability were reviewed. Component malpositioning was found to be the major cause of recurrent instability in this successfully treated cohort.