The inverse relationship between areal bone mineral density (BMD), measured by dual energy X-ray absorptiometry (DXA), and fracture risk in postmenopausal women and older men is well documented and is widely used in clinical practice to predict fracture risk, to aid treatment decisions and to monitor therapy. The proximal femur and lumbar spine are the most commonly measured sites; however, particularly in older people, the accuracy of lumbar spine measurements may be impaired and the proximal femur is most commonly used in the prediction of fracture risk. In addition, lateral views of the spine obtained by DXA are used to detect vertebral fracture and single energy images of the proximal femur can be used to visualize features associated with the development of atypical femoral fracture.
Although DXA-derived BMD has high specificity in predicting fracture risk its sensitivity is low, so that the majority of fragility fractures occur in individuals who do not have osteoporosis as defined by a BMD T-score ≥-2.5. BMD does not capture all aspects of bone microarchitecture, structure and quality that influence bone strength and fracture risk. In addition, the effect of risk factors such as previous fracture, parental history of hip fracture, glucocorticoid therapy, bone turnover and falls on fracture risk are partially independent of BMD. Algorithms such as FRAX that incorporate some of these factors are widely used and in the future, additional refinements may improve further our ability to predict fracture risk in clinical practice.
Disclosure of Interest None declared