Capsular Closure Outweighs Head Size in Preventing Dislocation Following Revision Total Hip Arthroplasty (THA)

Dislocation is one of the most common complications after revision THA using the posterolateral approach. Although the cause of dislocation after revision THA is multifactorial, the historically high dislocation rates have been shown to be significantly reduced by closing the posterior capsule and by the use of large diameter (36 and 40 mm) femoral heads. The relative importance of each of these strategies on the rate of dislocation remains unknown. We undertook a study to determine if increasing femoral head diameter, in addition to posterior capsule closure would influence the dislocation rate following revision THA.

We retrospectively reviewed 151 consecutive patients who underwent a revision THA. All patients were identified from our prospective arthroplasty database. We included all patients who underwent revision THA with closure of the posterior capsule and who had at least a 2-year minimum follow-up. We excluded patients undergoing a revision THA for dislocation or multistage revision for infection since these patients would likely have deficient posterior tissues.Posterior precautions with flexion restricted to 90 degrees was enforced for 3 months postoperatively. Forty-nine patients had a 28 mm femoral head, 51 had a 32 mm head and 49 patients had a 36 mm femoral head.

At a minimum follow-up of 2 years, there were 3 dislocations. There were no dislocations in the 28 mm group (0%), 3 in the 32 mm group (3%) and 0 in the 36 mm group (0%). All patients were successfully treated with a closed reduction. No patients had recurrent dislocation. Radiographs confirmed appropriate implant alignment, leg lengths, and restoration of normal hip biomechanics. Head size alone, was not found to significantly decrease the risk of dislocation.

Careful attention to surgical technique and closing the posterior capsule can decrease the historically high dislocation rate after revision THA when utilizing the posterolateral approach. The additional use of a large diameter head did not have a significant impact on the already low dislocation rate. Avoiding dislocation following revision THA requires careful attention to restoring hip biomechanics and the hip anatomy. Larger diameter heads may help in certain cases, but capsular closure outweighs the effect of femoral head diameter in preventing dislocation following revision THA through a posterolateral approach.