Microarchitecture in focus

Abstract

Osteoporosis is a complex disease characterized by a decrease in bone mass and alterations of bone quality leading to increased bone fragility and fracture risk. The increasing worldwide incidence of osteoporosis requires the use of effective treatments. The aim of antiosteoporotic treatments is to improve bone strength and thus to decrease the risk of fracture [1, 2]. Bone quality includes several aspects of bone composition and structure, including microstructure, bone turnover, the degree of mineralization, and the extent of microdamage. Bone quality is being given increased importance as recent observations demonstrate that traditional measures of bone density do not always predict fracture risk reliably [3]. At present, the major noninvasive measurement available for the diagnosis of osteoporosis is the measurement of areal bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA). Fracture risk prediction in the individual patient also relies mainly on BMD measurements. The diagnosis of osteoporosis measured by DXA, is a BMD of ≥2.5 standard deviations below the mean for young adults. However, many lines of evidence indicate that the decreased bone strength characteristic of osteoporosis is only partially accounted for by BMD and the remainder is dependent on material and structural properties of bone tissue, the bone microstructure [4–10]. Furthermore, the alterations in bone microstructure are not captured by BMD measurements. Measurements of BMD are useful in postmenopausal osteoporosis and other conditions of significant demineralization. Knowledge of bone microstructure is a clue for understanding osteoporosis pathophysiology and improving its diagnosis and treatment; the response of microstructure parameters to treatment should allow assessment of the real efficacy of the osteoporosis therapy.