A Study of Spinopelvic Relationship and its Impact on Functional Outcome of Total Hip Arthroplasty

Spinopelvic alignment plays a critical role in the biomechanics and functional outcomes of total hip arthroplasty (THA). This study evaluated changes in spinopelvic parameters following primary THA and their association with post-operative functional outcome.

This prospective observational study included 80 patients undergoing primary THA at a tertiary care teaching hospital between April 2024 and June 2025. Demographic characteristics, spinopelvic parameters in standing, sitting, lateral decubitus, and lateral decubitus with 90° hip flexion positions, and Harris hip score (HHS) were assessed preoperatively and postoperatively. Functional outcomes were evaluated at 2 days, 14 days, 3 months, and 6 months after surgery. Correlations between spinopelvic parameters and HHS were analyzed using Pearson's correlation coefficient.

The mean age of the patients was 48.33 ± 6.29 years, with males accounting for 60.0% of the study population. Significant post-operative improvements were observed in pelvic tilt (PT), sacral slope (SS), lumbar lordosis, and pelvic femoral angle (PFA) across different functional positions (all P < 0.05), whereas pelvic incidence (PI) remained unchanged (P = 0.87). Mean HHS improved significantly from 42.80 ± 6.50 preoperatively to 90.35 ± 4.75 at 6 months (P < 0.0001). PT demonstrated a significant negative correlation (r = -0.36, P = 0.010), while SS (r = 0.41, P = 0.003), PI (r = 0.39, P = 0.005), and PFA (r = 0.33, P = 0.018) showed significant positive correlations with functional outcome. All acetabular components were positioned within the Lewinnek safe zone.

Primary THA significantly improved spinopelvic alignment and hip function. Several spinopelvic parameters were significantly associated with post-operative functional outcome, highlighting the importance of comprehensive spinopelvic assessment during pre-operative planning and post-operative evaluation.