[Assessment of bone quality. Effects of bisphosphonates, raloxifene, alfacalcidol, and menatetrenone on bone quality: collagen cross-links, mineralization, and microdamage].

Bone loss and impaired bone quality have been proposed as major causes of increased bone fragility in osteoporosis. The proposed determinants of the material properties of bone are the degree of secondary mineralization, microdamage accumulation, and collagen cross-link formation that is affected by bone turnover rate. Recently, we demonstrated that (1) three years bisphosphonate increases the degree of mineralization, collagen maturity, and non-enzymatic cross-link, pentosidine without changing the amount of enzymatic cross-link and (2) the changes in collagen cross-link formation after treatment of bisphosphonate were associated with microdamage accumulation, which were independent of the mineral content (Saito M, Osteoporos Int, in press) and (3) urinary excretion of pentosidine predicts vertebral fracture (Shiraki M, Saito M, et al, J Bone Miner Metab, 2008) . In this review, I described effects of drugs for osteoporosis on bone material properties.