Geometry of the proximal femur in relation to age and sex: a cross-sectional study in healthy adult Danes

PURPOSE: To describe the natural variation in hip geometry in relation to Danish population characteristics, and to establish normal reference values. MATERIAL AND METHODS: We included 249 healthy individuals (94 M and 155 F, aged 19-79 years) and measured hip-axis-length (HAL), neck-width (NW), neck-shaft-angle (NSA), and femoral head-radius (HR) on dual-energy X-ray absorptiometry (DXA) screen images. RESULTS: HAL, NW, HR, and NSA were higher in men than in women (10.9 +/- 0.7 vs. 9.5 +/- 0.6 cm (P<0.001), 3.8 +/- 0.3 vs. 3.3 +/- 0.3 cm (P<0.01), 2.5 +/- 0.3 vs. 2.3 +/- 0.2 cm (P< 0.001), and 131 +/- 5 vs. 129 +/- 5 degrees (P< 0.01). NSA was higher in post-menopausal than in pre-menopausal women (130 +/- 4 vs. 128 +/- 5 degrees (P<0.001)). In multiple regression analysis, HAL, NW, and HR were positively related to body height in both sexes (R = 0.20 to 0.63, P<0.05 to P<0.001). In females, NSA was positively related to body height (R = 0.20, P<0.05) and negatively to body weight (R = -0.30, P<0.01). NW increased with age in men (R = 0.34, P<0.01) but not in women. CONCLUSION: Hip dimensions differ between genders in the Danish population. HAL, NW, and HR depend on body height. Finally, NW increases with age in men but not in women.