Bone densitometry: Science and practice

Abstract

Dual-energy X-ray absorptiometry (DXA) scans to measure bone mineral density (BMD) at the spine and hip have an important role in the evaluation of individuals at risk of sustaining an osteoporosis-related fracture and in helping clinicians advise patients about the appropriate use of anti-fracture treatment. Compared with alternative bone densitometry techniques, hip and spine DXA examinations have a number of advantages that include a consensus that BMD results should be interpreted using the World Health Organization (WHO) T-score definition of osteoporosis, a proven ability to predict fracture risk, proven effectiveness at targeting anti-fracture therapies, and the ability to monitor response to treatment. This review discusses the evidence for these and other clinical aspects of DXA scanning. Particular attention is paid to the new WHO FRAX® algorithm, which uses clinical risk factors in combination with a hip DXA scan to predict a patient's 10-year risk of experiencing an osteoporotic fracture. We review the recently published clinical guidelines that incorporate the FRAX fracture risk assessment tool in decisions about patient treatment and discuss the reasons why a quantitative evaluation of fracture risk should become the standard approach to the clinical interpretation of DXA examinations in postmenopausal women and older men.