An early-life femoral shaft fracture and bone mineral density at adulthood.

Abstract

High peak bone mass and density in early adulthood is an important protective factor against osteoporotic fractures in later life, but it is not known whether injuries to growing bones adversely affect the attainment of peak bone mass and density. The purpose of this study was therefore to examine with dual-energy X-ray absorptiometry the areal bone mineral density (BMD) of the injured and uninjured extremity (the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia and distal tibia), lumbar spine and distal radius of young adults with a history of an early-life femoral shaft fracture and to find out whether the fracture had affected the attainment of peak bone density of these patients. Thus, the BMD and clinical status of 41 patients (28 men, 13 women) who had sustained a femoral shaft fracture in childhood or adolescence (between 7 and 15 years of age, average 13 years before the study) were examined. The fracture had led to a statistically significant difference in BMD between the injured and uninjured side distal to the fracture site (men/women: distal femur, -3.7%/-3.9%; patella, -3.1%/-5.9%; proximal tibia, -2.0%/-4.6%; distal tibia, -3.4%/-5.2%), whereas the proximal femur did not show such differences. The male patients' spinal BMD was significantly lower (-7.9%) than that in their age-, height- and weight-matched healthy controls. The female patients' spinal BMD tended to be fairly comparable (-1.6%) to that of the controls (NS). In summary, this study indicates that early-life femoral shaft fracture results in a moderate (-2% to -6%) long-term side-to-side BMD difference distal to the fracture site. Patients' spinal BMD values also tend to be lower than that of controls. Thus, a femoral shaft fracture sustained in childhood or adolescence seems to disturb somewhat the attainment of peak bone density, the important predictor of osteoporotic fractures in later life.