To evaluate the efficacy of a commercially available acetabular positioning device, we performed a prospective evaluation of 40 consecutive patients undergoing primary total hip arthroplasty. All surgery was performed by the same surgeon, in the same operating room, and on the same operating table. The acetabular positioning device was designed to place the component in 45° of abduction. At 6 weeks, all radiographs were evaluated by 3 investigators not involved with the surgery. Each radiograph was evaluated by each reviewer on 3 separate occasions, blinded to the findings of the other reviewer in order to assess interobserver and intraobserver variability.
The mean cup abduction angle was 42.1° with a range from 23 to 57 degrees (std dev 8.3°). Intraobserver and interobserver variability was 0.2 and 0.3° respectively. The findings of this study demonstrate a wide variability in acetabular cup placement in primary total hip arthroplasty. We believe this is due to movement of the pelvis which may occur during preparation, draping and retracting during surgery. We feel surgeons should not rely solely upon positioning devices when implanting the acetabular component in total hip arthroplasty. Identification of bone landmarks and determination of superolateral implant coverage noted on preoperative templating is advocated to improve the precision of component position.
About the HSS Journal
HSS Journal, an academic peer-reviewed journal, is published twice a year, February and September, and features articles by internal faculty and HSS alumni that present current research and clinical work in the field of musculoskeletal medicine performed at HSS, including research articles, surgical procedures, and case reports.