Sex- and age-specific differences in femoral head coverage and acetabular morphology among healthy subjects-derivation of normal ranges and thresholds for abnormality.

OBJECTIVE: We aimed to clarify sex- and age-specific differences in three-dimensional and anatomic characteristics of femoral head coverage and acetabular morphology in healthy subjects.

MATERIALS AND METHODS: The study included 120 healthy subjects (57 male, 63 female), stratified into groups according to age and sex. We used computed tomography data to measure various anatomic alignment parameters describing femoral head coverage and acetabular morphology.

RESULTS: The lateral sector angle in the coronal plane, anterior sector angle in the sagittal plane, and posterior sector angles in the axial plane, which characterize femoral head coverage, did not differ significantly between males and females. However, the Sharp angle in the coronal plane and acetabular anteversion in both the sagittal and axial planes were significantly larger in females than in males. Overall, the age-specific trends were similar between male and female subjects. Specifically, for both males and females, the values for parameters of femoral head coverage were significantly lower in younger subjects (<50 years) than in older subjects (≥50 years); the only exception was the posterior sector angle among females; regarding acetabular morphology, younger subjects showed significantly higher values for the acetabular roof obliquity and Sharp angle, but no difference between younger and older subjects was noted regarding acetabular anteversion in the sagittal or axial plane.

CONCLUSION: Our data regarding sex- and age-specific differences and estimated normal ranges for parameters characterizing femoral head coverage and acetabular morphology among healthy subjects can be used to predict normal hip morphology.