Loss of Bone Density and Lean Body Mass after Hip Fracture

Abstract:

Few studies of bone loss have assessed the amount of loss directly after a hip fracture. The present prospective study was conducted to determine changes in bone mineral density (BMD) and muscle mass shortly after fracture and through 1 year to assess short-term loss and related factors. The setting was two acute care teaching hospitals in Baltimore, Maryland, and subjects were 205 community-dwelling women with a new fracture of the proximal femur between 1992 and 1995. Bone density of the nonfractured hip and whole-body and body composition were measured by dual-energy X-ray absorptiometry at 3 and 10 days and 2, 6 and 12 months after admission. Mean BMD of the femoral neck was 0.546 ± 0.007 g/cm² at baseline. Average loss of femoral neck BMD from baseline was 2.1% at 2 months, 2.5% at 6 months and 4.6% at 12 months. The average loss of BMD in the intertrochanteric region was 2.1% at 12 months. Total lean body mass decreased by 6% while fat mass increased by 3.6% by 1 year after the fracture. These findings indicate that significant loss in BMD and lean body mass occur shortly after hip fracture while body fat increases. Continued loss was evident throughout the 1 year of follow-up. This loss of both bone density and muscle mass may lead to new fractures.