Characteristics of long bone DXA reference data in Hong Kong Chinese

With the increasing number of geriatric long bone fractures, the establishment of long bone reference BMD data is desirable for the accurate diagnosis of osteoporosis, study of fracture mechanics, implant design, and indications for augmentation of fracture fixation with biomaterials. We report the normal reference bone mineral density (BMD) and bone mineral content (BMC) at three femoral sites (proximal, diaphyseal, and distal) in 106 male and 93 female Hong Kong Chinese aged 12 to 80, measured with dual-energy X-ray absorptiometry (DXA). The length and width of the femur were also measured. The results suggest that males reached peak bone mass earlier than females and the value was also higher in all measured sites. After reaching the peak bone mass, bones lost BMD faster in females. The age-related annual bone loss (in BMD) calculated with a regression model in female subjects were, on average, 3.3, 4.0, and 3.0 times higher than those in males at the diaphyseal, proximal, and distal regions, respectively. The decrease in BMD and BMC occurred slightly earlier in the proximal and distal regions than the diaphysis in both sexes. The male femur was significantly longer than that of the female in all age groups after 20 yr of age and remained unchanged with advancing age. The femoral width in females showed an increasing trend from adolescence. Our study provides reference data for the changes in diaphyseal BMC and BMD associated with aging. The age-related changes in the femoral diameter in females might attenuate the negative impact on fracture risk as a result of decreasing BMD with age.