Use of a Sentinel Pin as a Guide to Acetabular Component Anteversion in Total Hip Arthroplasty

Malpositioning of the acetabular component is a common problem associated with the posterior or posterolateral approach to total hip arthroplasty. Retroversion is also a common problem due to forward rolling (or internal rotation) of the patient during anterior femoral retraction (Fig. 1). Hassan et al. stated that anteversion cannot be assessed accurately during surgery1. Dorr et al. recommended the use of anatomical landmarks at the time of surgery to avoid this problem2. Others have recommended the use of computer-assisted navigation as a method to ensure proper acetabular component alignment3. Asayama et al. assessed intraoperative pelvic motion during total hip arthroplasty with use of a pelvic tilt goniometer that was composed of a digital compass and a three-direction indicator4. We describe an accurate and simple method to measure and correct forward roll during total hip arthroplasty.