Late instability following total hip arthroplasty.

Instability is one of the most common complications after total hip arthroplasty and can present early or late after hip replacement. Late instability is considered if the event occurs five or more years after the primary arthroplasty, and in contrast to early dislocation, it appears to require operative intervention. The incidence of late instability may be greater than initially appreciated, and the cumulative rate rises with longer follow-up. The etiology of hip instability is often multifactorial with the presumed risk factors for late instability including long standing malposition of the components, trauma, deterioration in muscle mass, neurological status impairment and polyethylene wear. This article presents a synopsis of published studies on late instability and outlines our institutional experience with treatment of late dislocation following total hip arthroplasty occurring due to polyethylene wear.