How Does Surgical Approach Affect Characteristics of Dislocation After Primary Total Hip Arthroplasty?

Background: Concerns have been voiced regarding how surgical approach impacts risk of dislocation after total hip arthroplasty (THA). This study investigated how surgical approach impacts rate, direction, and timing of dislocations following THA. Methods: We conducted a retrospective review of 13,335 primary THAs from 2011 to 2020 and identified 118 patients with prosthetic hip dislocation. Patients were stratified into cohorts by surgical approach used during primary THA. Patient demographics, index THA acetabular cup positioning, number, direction, timing of dislocations, and subsequent revisions were collected. Results: Dislocation rate differed significantly between posterior approach (PA), direct anterior approach (DAA), and laterally-based approach (LA) (1.1 versus 0.7% versus 0.5%, P = .026). Rate of hips dislocating anteriorly was lowest in the PA group (19.2%) compared to LA (50.0%) and DAA groups (38.2%, P = .044). There was no difference in rate of hips dislocating posteriorly (P = .159) or multidirectional (P = .508) instability; notably 58.8% of dislocations in the DAA cohort occurred posteriorly. There were no differences in dislocation timing or revision rate. Acetabular anteversion was highest in the PA cohort compared to DAA and LA (21.5 versus 19.2 versus 11.7 degrees, P = .049). Conclusion: After THA, patients in the PA group had a slightly higher dislocation rate compared to the DAA and LA groups. The PA group had a lower rate of anterior dislocation and nearly 60% of DAA dislocations occurred posteriorly. However, with no differences in other parameters including revision rates or timing, our data suggests surgical approach may impact dislocation characteristics to a lesser degree than previous studies have suggested. (c) 2023 Published by Elsevier Inc.