Can Preoperative Factors Predict the Need for Femoral Soft-Tissue Releases in Direct Anterior Approach Total Hip Arthroplasty?

Background Releases of the superior hip capsule, conjoint tendon, and piriformis tendon are variably required to achieve adequate femoral exposure during direct anterior approach (DAA) primary total hip arthroplasty (THA). This study evaluates the correlation between patient demographic factors and preoperative radiographic measurements on femoral soft tissue releases. Methods A retrospective cohort study of 145 consecutive primary total hip arthroplasties performed by a single surgeon was conducted. Patient demographics (sex, age, BMI) and preoperative standing radiographs were analyzed for femoral plumb line (FPL), femoral neck angle (FNA), femoral neck length (FNL), and articulo-trochanteric distance (ATD). Releases were performed sequentially as needed for femoral exposure: superior hip capsule, conjoint tendon, and piriformis tendon. Multivariate binary logistic regression determined whether these preoperative variables predicted the need for soft-tissue releases. Results BMI was higher among patients with at least 1 release (30.1 vs 26.0 kg/m 2 ; P = .003). Female sex and left laterality were associated with lower odds, while older age increased the odds of all 3 releases (OR 1.049; 95% CI 1.005-1.096; P < .05). Larger ATD (OR 0.887; 95% CI 0.831-0.948; P < .001) and higher FPL (OR 0.965; 95% CI 0.940-0.991; P < .01) decreased the likelihood of multiple releases. Longer FNL increased the odds of conjoint release (OR 1.090; 95% CI 1.008-1.178; P < .05). FNA was not a significant predictor. Conclusions Male sex, older age, higher BMI, and longer FNL were associated with greater need for femoral releases. Larger ATD and higher FPL were protective against needing soft-tissue releases.