BLACK-WHITE DIFFERENCES IN HIP GEOMETRY

Previous studies have demonstrated that reduced thickness of the femor al neck and shaft cortex, a wider intertrochanteric region and a longe r hip axis length were predictive of hip fracture among Caucasian wome n, We hypothesized that racial differences in these features of hip ge ometry may contribute to explaining the differences in hip fracture in cidence between women of African origin and Caucasian women. We measur ed the cortical thickness and bone widths in 132 African-American wome n and 43 Nigerian women who were pair-matched on height (+/- 3 cm), ag e (+/- 5 years) and weight(+/- 3 kg) to 175 Caucasian women. Measures of cortical thickness were greater among women of African origin than Caucasian. Women of African origin had smaller bone widths and a short er hip axis length than Caucasians. Several of these differences were independent of bone mineral density except for the cortical thickness of the femoral shaft. We conclude that women of African origin have th icker cortical bone of the hip, a shorter hip axis length and smaller intertrochanteric widths than Caucasians. Based on a model developed f rom hip fractures among Caucasian women, we predict that these observe d racial differences could contribute to approximately a 25% decrease risk of hip fracture among blacks.