Magnetic resonance imaging features of preserved vs divided and repaired piriformis during total hip arthroplasty: a randomized controlled trial.

The aim of this study was to compare the muscle grade and bulk of the divided and repaired piriformis tendon by the standard posterior approach with the preserved tendon by a piriformis-sparing (PS) approach, in total hip arthroplasty. Twenty-two patients were randomized to either approach. Patients received preoperative and 3 months and 2 years postoperative magnetic resonance imaging scans. Patients and evaluators were blinded to allocation. There was significantly less deterioration in piriformis muscle grade (P = .029) and bulk (P = .015) in the PS group at 3 months. At 2 years, only the difference in grade remained significant (P = .001). There was no difference in Oxford hip scores. In conclusion, a PS approach avoids the marked wasting and deterioration in muscle grade that occurs postoperatively in the standard posterior approach.