Racial differences in femoral dimensions and their relation to hip fracture.

White women have a higher rate of age-specific hip fractures than black women. Recently, femoral dimensions have been implicated in osteoporotic fractures. To study racial differences in femoral dimensions, dual X-ray absorptiometry scans were obtained for two similar groups of 50 white women and 50 black women. We measured the hip axis length (the distance from below the lateral aspect of the greater trochanter to the inner pelvic brim), the neck width and the neck/shaft angle on the scan print-out. The observer was masked to the race of the subject. The results were analyzed using the independent t-test and showed that the hip axis length and the neck width were significantly longer in the white women than in the black women (p values < 0.05 and < 0.02 respectively) but that the neck/shaft angle was not statistically different in the two groups. We conclude that femoral geometry differs among races. Whether this contributes to the lower risk of hip fracture in black women will require prospectively based studies.