Three-Dimensional Templating for Acetabular Component Alignment During Total Hip Arthroplasty.

Abstract

Appropriate placement of the acetabular cup is an important determinant of implant stability and longevity. Malposition of acetabular cups negatively influences prosthesis survival and leads to an increased dislocation rate. The objective of the study was to determine the role of 3-dimensional templating in obtaining accurate acetabular component placement in total hip arthroplasty. In this computed tomography-based study, the authors identified 93 patients who underwent primary total hip arthroplasty with computer-assisted navigation. Using 3-dimensional planning, the authors templated the acetabular component at an inclination of 40° and anteversion of 20°. To classify acetabular cup coverage by bone, the acetabulum was used as a clock face with the center of the transverse acetabular ligament (TAL) as 6-o'clock. Analyses revealed that 72% of cups were uncovered between 9- to 1-o'clock for right hips. On the left side, 88% of cups were uncovered between 11- to 3-o'clock. Across all hips, 74% of cups had a 1-o'clock position at the most lateral aspect. Further analysis revealed that 46% of acetabular cups had a teardrop at the same level of the most inferior aspect of the cup, whereas only 37% of cups had a teardrop above the inferior aspect of the cup. Finally, the acetabular component was aligned with the TAL in 76% of hips, retroverted to the TAL in 16%, and anteverted to the TAL in 8%. The current study demonstrates a useful gross intraoperative reference tool to standardize cup position without the need for additional equipment and reliance on anatomical landmarks. [Orthopedics. 2017; 40(4):e708-e713.].