Bone mineral density of the hip measured with dual-energy X-ray absorptiometry in normal elderly women and in patients with hip fracture

Abstract

Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA) in 133 normal females on five regions of the femoral site: neck, trochanteric, intertrochanteric, Ward’s triangle, and total area of the proximal femur. One hundred and twenty-five women (56 older than 65, range 65–97, and 69 with an age range of 21–65) were also examined for spinal bone mineral density. The mean in vivo precision (CV%) of the measurements with respositioning assessed on five young and eight elderly patients was ranged from 0.7% to 1.7% but lowerfor Ward’s triangle (CV=2.95% and 3.87%). Between 30 and 90 years, a linear age-related bone mineral decrease was found at all sites with a similar magnitude of bone loss for the femoral neck, total or intertrochanteric regions (−33% to −39%). A greater decrease was found for the Ward’s triangle region (−61 %). In the subgroup of elderly women (65–97 years old), the lumbar BMD measured with an anteroposterior incidence did not decrease significantly with age, contrasting with an average 27% decrease of the BMD of the hip between 65 and 90 years of age. In addition, 31 patients suffering either from a cervical (n=12) or pertrochanteric (n=19) fracture were measured on their contralateral. femur 15 to 30 days after the fracture event. The mean calculated BMD values were, depending on the measured area, from 14% to 21% lower than those reported for age-matched controls (z-score from −1.11 to −0.65). A fracture threshold was determined for each site from this population and the elderly controls. The best discrimination between patients and controls was obtained at the femoral neck site, with a value of 0.57 g/cm² providing a specificity of 69% with a sensitivity of 75%. In conclusion, bone mineral content of the proximal femur can be measured with an acceptable precision by dual-energy X-ray absorptiometry. In elderly people, this site appears more suitable than the lumbar spine for the detection of age-related bone loss. Bone mineral density appears to be one major determinant in the causation of hip fracture.