Maternal history of osteoporosis and femur geometry.

ABSTRACT

Most studies that have examined the role of skeletal factors in the relationship between an individual's family history of fracture or osteoporosis and their fracture risk have focused on bone density. In this study, we expanded the scope of skeletal factors to include geometric properties (subperiosteal width, section modulus, cortical thickness, and buckling ratio) in addition to areal bone mineral density (BMD). We compared these skeletal factors at the femur neck and shaft by self-reported maternal history of osteoporosis (OP HX) from 5334 non-Hispanic whites, ages > or =20 years in the Third National Health and Nutrition Examination Survey (NHANES III, 1988-94). A total of 213 men and 315 women reported a positive OP HX (e.g., their biological mother had sustained a hip fracture after age 50 years or had a physician's diagnosis of osteoporosis). Differences in bone density and geometry by OP HX were examined after adjusting for potential confounding variables. Several bone parameters differed significantly by OP HX in both sexes at the femur neck, but none differed at the femur shaft. At the neck, those with a positive OP HX had values that differed by approximately 3% to 4% (lower for BMD, bone mineral content (BMC), cross-sectional area, and cortical thickness; higher for buckling ratios) from those with a negative OP HX (P < 0.05). The magnitude of these relationships was similar in both sexes, but differences were greater in younger versus older adults. In conclusion, both men and women with a positive maternal history of osteoporosis may be at greater risk of femur neck fracture owing to thinner cortices and lower BMC, which in turn results in potentially greater cortical instability (buckling ratio) at this skeletal site.