No Increase in Instability with Obturator Externus Release in Direct Anterior Approach

Use of the direct anterior approach in total hip arthroplasty is becoming increasingly common. Complications associated with this approach pertain to proximal femoral exposure. Selective capsular and tendinous releases improve exposure intraoperatively. Release of obturator externus has been avoided to prevent postoperative instability. A retrospective casecontrol review of consecutive patients who underwent direct anterior approach was performed. Demographic information, sequence of releases performed, dislocations that occurred postoperatively, and revision total hip arthroplasties (THAs) were recorded. Overall dislocation rate was 0.6% (2/340). Obturator externus release was performed in 169 cases (49.7%). Both groups with and without release experienced a single dislocation event (p = 1.0). Overall revision rate was also 0.6% (2/340). One dislocation underwent revision for instability. Selective release of obturator externus after other releases have failed to improve proximal femoral exposure does not result in an increased rate of postoperative hip instability in direct anterior approach THA. (Journal of Surgical Orthopaedic Advances 30(2):082–084, 2021)

Key words: direct anterior, obturator externus, dislocation