Trabecular Bone Mechanical Properties in Patients with Fragility Fractures

Abstract

Fragility fractures are generally associated with substantial loss in trabecular bone mass and alterations in structural anisotropy. Despite the high correlations between measures of trabecular mass and mechanical properties, significant overlap in density measures exists between individuals with osteoporosis and those who do not fracture. The purpose of this paper is to provide an analysis of trabecular properties associated with fragility fractures. While accurate measures of bone mass and 3-D orientation have been demonstrated to explain 80% to 90% of the variance in mechanical behavior, clinical and experimental experience suggests the unexplained proportion of variance may be a key determinant in separating high-and low-risk patients. Using a hierarchical perspective, we demonstrate the potential contributions of structural and tissue morphology, material properties, and chemical composition to the apparent mechanical properties of trabecular bone. The results suggest that the propensity for an individual to remodel or adapt to habitual damaging or nondamaging loads may distinguish them in terms of risk for failure.

Techniques for Computing Fabric Tensors: A Review

“…evidences supporting that changes in the anisotropy and orientation of trabecular bone are associated with osteoporosis has been reported [11,32,47]. Figure 1 show renderings from two in vitro specimens 1 .…”

Treatment of acromegaly increases BMD but reduces trabecular bone score: a longitudinal study

“…The external and internal architectures of bones are important factors for the distribution and transmission of loads (18). A combination of structural and densitometric indices might potentially provide a more accurate assessment of bone quality (19).…”

Biomechanics of Musculoskeletal Injury

“…Microarchitectural changes in trabecular bone, such as decreased number of trabecular plates and decreased connectivity between plates, appear to play a large role in decreased strength of trabecular bone. Decreases in bone mass and changes in distribution of bone mass also appear to play a large role in overall bone strength (McCreadie & Goldstein, 2000;Kreider & Goldstein, 2009). It is well established that endosteal expansion (increase in inner cortical radius due to loss of cortical bone) and perioesteal expansion (increase in external cortical radius due to deposition of new bone on the external surface of bone cortex) both occur, but that endosteal expansion exceeds periosteal expansion (Figure 1).…”

“…This increased anisotropy leads to a reduced ability to withstand off-axis impact, during a fall in a direction different from the direction of habitual loading, such as a sideways fall. In these patients, bone reorganization may be overcompensating for the low mass status by increasing the degree of anisotropy so that strength of the bone is only maximized in the frequently loaded direction (Kreider & Goldstein, 2009;Ciarelli et al, 2000;McCreadie & Goldstein, 2000).…”