Previous studies have shown that the mechanical properties of trabecular bone are determined by bone volume fraction (BV/ TV) and microarchitecture. The purpose of this study was to explore other possible determinants of the mechanical properties of vertebral trabecular bone, namely collagen cross-link content, microdamage, and mineralization. Trabecular bone cores were collected from human L2 vertebrae (n ¼ 49) from recently deceased donors 54-95 years of age (21 men and 27 women). Two trabecular cores were obtained from each vertebra, one for preexisting microdamage and mineralization measurements, and one for BV/TV and quasi-static compression tests. Collagen cross-link content (PYD, DPD, and PEN) was measured on surrounding trabecular bone. Advancing age was associated with impaired mechanical properties, and with increased microdamage, even after adjustment by BV/TV. BV/TV was the strongest determinant of elastic modulus and ultimate strength (r 2 ¼ 0.44 and 0.55, respectively). Microdamage, mineralization parameters, and collagen cross-link content were not associated with mechanical properties. These data indicate that the compressive strength of human vertebral trabecular bone is primarily determined by the amount of trabecular bone, and notably unaffected by normal variation in other factors, such as crosslink profile, microdamage and mineralization. Keywords: bone strength; microdamage; microarchitecture; mineralization; collagen cross-links; vertebral trabecular bone Several studies have shown that the mechanical properties of trabecular bone are influenced by bone volume fraction (BV/TV) and microarchitecture. 1,2 However, additional factors, such as degree of mineralization, preexisting microdamage, and collagen cross-link profile may also play a role, yet the contribution of these factors to human trabecular bone mechanical properties remains incompletely understood.Increased mineralization of cortical bone is exponentially related to increased stiffness, but decreased energy absorption. 3 A similar trend was seen in human trabecular bone from the calcaneus, with a positive relationship between mineralization and elastic modulus, after adjusting for BV/TV. 4 It has also been suggested that a reduction in the heterogeneity of mineralization density distribution leads to increased bone fragility, 5 but there are few data to support this assertion.Microdamage has been largely studied in animal models and in human cortical bone, with only a few studies reporting microdamage in human trabecular bone either naturally occurring 6-11 or due to loading ex-vivo. 12 In cortical bone, microdamage accumulation leads to decreased mechanical properties, 13,14 and therefore has been implicated in skeletal fragility and stress fractures. 15 However, the association between microdamage and cortical bone fracture toughness was weak, 16 raising questions as to the role of microdamage in cortical bone. Increased microdamage has also been associated with decreased strength in human vertebral cancellous bone; 1...