Stability of total hip arthroplasty in patients 75 years or older.

Increasing patient age (> 75 years) is a known risk factor for dislocation of total hip arthroplasty. This is a study of total hip arthroplasties by one surgeon in patients 75 years or older to determine the prevalence of dislocation and a review of the surgical options for prevention and treatment of instability in this population. Of 140 primary total hip arthroplasties done in patients 75 years or older who were followed up for at least 1 year, the preoperative diagnosis was osteoarthritis in 82% and the mean followup time was 4 years. The acetabular component was cementless: modular in 121 arthroplasties and cemented in 19 arthroplasties. There were five dislocations (3.5%), but only two were recurrent and the patients were treated successfully by modular component exchange. Bipolar arthroplasty has a lower rate of dislocation, but there are problems with residual pain and high rates of reoperation, wear, and osteolysis. Constrained components may be indicated in older patients with dementia, abductor insufficiency, or failure of modular exchange. Large femoral heads, to increase the range of motion before dislocation occurs, may be used with highly cross-linked acetabular liners. Modular cementless acetabular components are preferable in patients who are 75 years or older. A 28-mm or 32-mm femoral head is recommended, but larger femoral heads should be considered in patients with fractures and for the treatment of recurrent dislocation.