Spinopelvic Parameters and Functional Outcomes after Total Hip Arthroplasty: A Prospective Evaluation in a Young Cohort

Abstract Background: The spine–pelvis–hip complex influences total hip arthroplasty (THA) outcomes, but prospective data on spinopelvic parameters and early functional recovery remain limited, particularly in younger cohorts. Objective: The objective of this study was to evaluate whether static spinopelvic parameters such as sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI) and their association with functional outcomes on the Harris Hip Score (HHS) after THA. Methodology: A prospective study of 30 patients (mean age: 37.1 ± 14.5 years, 77% of males) undergoing cementless primary THA primarily for avascular necrosis (67%). Radiographic measurements of SS, PT, and PI and HHS for functional outcomes were taken at 6 weeks, 3 months, and 6 months postoperatively. Repeated-measures analysis of variance, correlations, and regression analysis were done. Results: HHS improved significantly from 90.5 ± 3.7 (6 weeks) to 94.3 ± 3.5 (6 months; P < 0.001, η 2 = 0.76). Static SS increased modestly (42.6° to 43.7°, P < 0.01), PT decreased (12.0° to 11.0°, P = 0.08), and PI remained stable (54.6°, P = 0.99). Baseline SS, PT, and PI showed no significant correlation with HHS at any time points (all |r| <0.30, P > 0.05). Multivariable regression analysis confirmed that these static parameters did not independently predict functional outcomes (all P > 0.1). PI = SS + PT residuals (0.2° ± 0.9°) confirmed reliability. Conclusion: Early THA functional gains occur independently of baseline spinopelvic alignment in young patients. Minimal changes in static parameters suggest that young spines adapt well after THA, which can reassure clinicians about the prognosis in this demographic.