Beyond bone mineral density: new developments in dual X-ray absorptiometry assessment of bone quality

Abstract

Bone mineral density, bone texture, bone geometry and bone strength are all elements necessary for a proper osteoporotic fragility fracture prediction assessment. Data regarding bone quantity (density) and, in part, bone quality (structure and geometry) are obtained by the gold standard method of dual X-ray absorptiometry (DXA), while data about bone strength are obtained by means of a new DXA index called the bone strain index (BSI). The BSI evaluates bone resistance by means of average strain calculation, and it is based on finite element analysis applied to DXA spine and femoral scans. The BSI includes local information on bone density distribution, bone geometry and, unlike variables of bone mineral density and bone quality such as the trabecular bone score, it represents the status of the bone in a particular loading condition. This review illustrates the methodology for calculating the BSI and discusses findings on its reproducibility and data about its capability to predict fragility fractures and monitor pharmacological treatment for osteoporosis.