Radiographic parameters of pelvic and proximal femoral morphology do not predict outcomes for direct anterior total hip arthroplasty

Abstract

BackgroundRadiographic predictors of outcomes associated with direct anterior approach (DAA) total hip arthroplasty (THA) are largely unknown. Anecdotally, some surgeons limit surgery to patients with low body mass index (BMI) or “favorable” bony morphology. Objective data on the impact of these factors is limited. We sought to determine radiographic and demographic predictors of outcomes after DAA arthroplasty. MethodsA consecutive series of patients undergoing unilateral, elective DAA THA, who had linked pre- and post-operative patient reported outcome scores, from January 1, 2017 to March 30, 2019 were included. Radiographic measurements, including proxies for pelvic overhang, femoral canal access, acetabular morphologic changes, and markers of disease severity, were performed on calibrated radiographs. Intra-observer consistency was also evaluated. Outcome measures included disease specific and general health patient-reported outcomes scores, while surgical difficulty was approximated by estimated blood loss and surgical time. Multivariate analyses were performed to determine statistically significant correlations. Results168 patients were included. Overall, patients experienced significant improvement in outcome scores (mean ∆ HOOS-JR 39.4, PROMIS-physical 12.3). There were two reoperations (1.2%), for recurrent dislocation. Female sex (p = 0.015) and increasing age (p == 0.019) were associated with shorter surgical times. No statistically significant correlations were found between the radiographic parameters and outcome measures. Intraclass correlation coefficients of the radiographic measurements were overall strong (0.73–1.0). ConclusionWe demonstrated consistent results in this series of patients despite variation in bony morphology. Our findings suggest that DAA THA can be safely performed on a broader patient population.