Anatomical Variations of the Acetabulum and Their Implications for Total Hip Arthroplasty: a Multicenter CT-Based Study

Abstract

Objective: To determine anatomical variations in acetabular morphology using computed tomography and evaluates their implications for total hip arthroplasty in a resource-constrained healthcare setting.

Methods: This multicenter retrospective cross-sectional study included 204 adults whose pelvic computed tomography scans were obtained at three tertiary-care hospitals in Pakistan between January 2023 and December 2024. Bilateral acetabular diameter, depth, depth-to-diameter ratio, anatomical anteversion, inclination, lateral center-edge angle, anterior wall index and posterior wall index were measured. Sex-related differences were assessed using generalized estimating equations, while side differences were evaluated through paired analysis. Interobserver reliability was determined in 40 randomly selected scans.

Results: A total of 408 acetabula from 110 men and 94 women were evaluated. Men had significantly larger acetabular diameters and depths, whereas women demonstrated greater anteversion and inclination. Clinically relevant variation in at least one measurement was identified in 79 (38.7%) participants. Smaller anticipated acetabular cup sizes were more frequent among women, while shallow acetabula commonly occurred with increased inclination and reduced lateral coverage. Mean differences between the right and left sides were small for all principal measurements. Measurement reliability was good to excellent, with intraclass correlation coefficients ranging from 0.84 to 0.94.

Conclusion: Acetabular morphology showed considerable individual and sex-related variation. Standardized evaluation of available pelvic CT scans could support cup-size selection, component orientation and preservation of acetabular bone during total hip arthroplasty without requiring costly navigation systems.