Improving Acetabular Component Positioning in Supine Direct Anterior Total Hip Arthroplasty with a Transparency...

A novel and simple method to ensure accurate acetabular component anteversion and inclination intraoperatively with the use of a transparency template is described.

Patients who underwent total hip arthroplasty (THA) via direct anterior approach (DAA) from June 2019 to January 2020 were included. A transparency template that can be placed over the image intensifier monitor to allow surgeons an accurate reading of the acetabular component position intraoperatively was designed, developed and utilized to determine effectiveness. The first template consists of two perpendicular lines indicating the "trans-ischial line" and the "pubic symphysis/coccyx". The second template consist of a line indicating 45° inclination and parallel lines of corresponding distances apart required to achieve 20° anteversion based on Lewinnek's formula: version=sin^-1 (D1/D2), where D1: minor axis and D2: major axis of the component. This template was used throughout the acetabular part of the surgery, from reaming to impaction of component. Postoperative acetabular inclination, anteversion, surgical duration, length of stay, as well as complications were recorded.

Twenty-six patients were included in this study. Mean postoperative acetabular cup inclination was 43.46±3.09° and mean version was 19.98±2.89°. A total of 21 patients (80.8%) fell within the Callanan safe zone and all 26 patients (100%) were within the Lewinnek safe zone.

The transparency template is a simple, reproducible, and effective tool with a minimal learning curve and no requirement for expensive equipment. This template has the potential to assist surgeons, especially those who are less experienced with DAA THA, in obtaining better postoperative radiographic outcomes.