Aim: Acetabular liner orientation has been widely studied in the context of instability and impingement after total hip arthroplasty (THA), yet its impact on postoperative hip range of motion (ROM) remains unclear. ROM may be influenced by multiple confounding factors, including limb length discrepancy (LLD), femoral offset, body mass index (BMI), smoking status, and soft-tissue procedures. Methods: This retrospective study included 92 hips that underwent primary THA with either a posterosuperior or posterior liner orientation. Demographic, radiographic, and surgical variables—including LLD, femoral offset, bursal repair, and postoperative drain output—were recorded. Hip ROM (flexion, abduction, internal and external rotation) was measured goniometrically at final follow-up. Correlation analyses and multivariable linear regression models were used to evaluate independent predictors of ROM. Results:Mean ROM did not differ significantly between the posterosuperior (n = 61) and posterior (n = 31) liner groups. LLD was independently associated with reduced flexion and external rotation. Abduction and internal rotation were positively associated with bursal repair and greater drain output, whereas higher BMI showed a trend toward reduced abduction. Smoking demonstrated a statistical association with higher abduction values, although this was likely confounded by patient characteristics. Overall, ROM variation was more strongly related to LLD and soft-tissue–related surgical factors than to liner orientation. Conclusion:Liner orientation (posterosuperior vs. posterior) did not significantly influence postoperative ROM after THA. Postoperative mobility was primarily determined by LLD and soft-tissue management. Surgical planning should prioritize correction of LLD and optimization of soft-tissue balance rather than relying on liner orientation to improve ROM.
Alkan et al. (Tue,) studied this question.