The Accuracy of Digital Templating for Primary Total Hip Arthroplasty: Is There a Difference Between Direct Anterior and Posterior Approaches?

Abstract

Background: The direct anterior approach (DAA) has gained recent popularity for total hip arthroplasty (THA), as it provides immediate feedback on cup position and limb length using fluoroscopy. The purpose of this study is to evaluate any differences in the accuracy of digital templating for preoperative planning of THA, performed with 2 different surgical approaches: DAA using a radiolucent table with intraoperative fluoroscopy and the posterior approach (PA).

Methods: One hundred thirty-one consecutive patients (148 hips) underwent a THA by a single surgeon, using the same cup and stem designs. Seventy-five hips were performed using the DAA using a fracture table and fluoroscopy. Seventy-three hips were performed using the PA with the patient positioned in lateral decubitus using standard positioners without fluoroscopy. Preoperative radiographs were digitally templated by the same surgeon.

Results: The PA patients had a higher mean body mass index and were more likely to have a preoperative diagnosis of avascular necrosis. The accuracy of templating for predicting the cup size to be within 2 mm was 91% for DAA vs 88% for PA (P = .61). For stem size, the accuracy was 85% (to within 1 size) for the DAA vs 77% for the PA (P = .71). Likewise, there was no significant difference in predicting the final stem's neck angle or femoral offset.

Conclusion: Digital templating was found to be a reliable and highly accurate method for predicting component sizes and offset for THA, regardless of using either the PA or the DAA with fluoroscopy.

Keywords: THA; accuracy; digital templating; direct anterior approach; fluoroscopy; posterior approach.