Bone Biomechanics and Bone Quality: Effects of Pharmaceutical Agents Used to Treat Osteoporosis

Abstract

The biomechanical properties of bone define skeletal fragility. Surrogates such as bone density or biochemical markers are used to estimate the mechanical properties of bone because mechanical properties cannot be measured in a clinical environment. Within the set of bone’s mechanical properties, the material properties of the tissue itself are the defining feature of bone quality. Because they are the summation of all bone quality characteristics, bone’s material properties can define whether bone is fragile or healthy, even though other studies are required to determine the exact characteristics of microarchitecture, microdamage, and tissue physical properties that make the bone more or less fragile. For these reasons, measurement of the mechanical properties of bone is critical to assess bone health following drug treatments meant to ameliorate low bone mass, and are a common outcome measure in preclinical studies that assess the potential of these medications. This review describes the effects of existing anti-catabolic (bisphosphonates, SERMS, RANKL inhibitors) and anabolic (rhPTH (1-34) agents used to treat osteoporosis, and also several emerging potential therapies (cathepsin K inhibitors, anti-sclerostin antibody), on bone’s structural and material mechanical properties.