In fact, the periosteal surfaces continue to add small amounts of bone throughout the postmenopausal period of bone loss [29, 62]. Antiresorptives: Mechanism of Action Bisphosphonates The first drug approved for treatment of osteoporosis in the United States was alendronate in 1995. in the bone remodeling space; however, the majority of their efficacy is due to suppression of the primary cause of osteoporosis, ie, excessive bone remodeling not driven by mechanical need. All of them improve some element(s) of bone quality. Conclusions Antiresorptive therapy reduces risk of fracture by improving bone quality through halting removal of bone tissue and the resultant destruction of microarchitecture of bone and, perhaps to some extent, by improving the intrinsic material NMS-P715 properties of bone tissue. Information presented here may help clinicians to improve selection of patients for NMS-P715 antiresorptive therapy by avoiding them in cases clearly not due to excessive bone remodeling. Introduction Bone quality is defined as those features of bone tissue that resist physiologic loading other than complete mass of bone tissue present in an individual adult human. These features include (1) macroarchitecture of bone tissue, (2) microarchitecture of bone tissue, (3) submicroscopic architecture NMS-P715 of bone tissue, (3) intrinsic material properties of bone tissue, and (4) efficiency of microdamage repair. However, in the broad sense, the concept of bone quality includes every feature of bone that affects the lifelong ability of the tissue to bear repeated physiologic mechanical loading without failure or fracture and includes the quantity present, ie, its mass. The macroarchitecture of bone tissue refers to the adult length and shape of the intact skeleton that is largely decided genetically. However, the final adult shape and mass of the skeleton depend on the genetic contribution interacting with modeling and mechanical loading during growth and development . The final product is also influenced by environmental factors, such as nutrition, intercurrent illness, and other factors encountered during growth and development. This is best analyzed by CT and quantitative CT. The microarchitecture of bone tissue refers to the morphology of trabecular bone tissue. Its features include the number, thickness, shape, connectivity, and volume of trabeculae occupying the marrow space. It is best analyzed microscopically by bone histomorphometry or micro-CT of iliac biopsy specimens [6, 58] and by high-resolution quantitative CT or MRI of the radius or other sites [22, 42]. The latter continues to be processed. The intrinsic material properties of bone tissue refer to the elasticity, toughness, and/or strength properties of bone tissue. They are the mechanical engineering properties of the bone tissue that are the products of features explained below. These are analyzed ex lover vivo in bones of animal models by classical engineering methods such NMS-P715 as application of measured loads to harvested bone specimens and measuring the relationship between loads and resultant deformation. The technology for measuring NMS-P715 this in humans is under development. One promising Rabbit Polyclonal to PKA-R2beta (phospho-Ser113) method is usually nanoindentation where embedded iliac specimens are obtained and an instrument is used to make small indents (~5?m) while monitoring the pressure used and the tissues ability to return to the preindented state . Of course, this requires iliac biopsy and ex vivo measurements around the specimens. Human data so far are scarce. The submicroscopic architecture of bone tissue refers to the chemical content and form of the bone tissue. Its features include size and morphology of hydroxyapatite crystals; incorporation of other minerals into the mineral phase; the concentration of mineral incorporated into the matrix; the organic makeup of the collagen molecules, ie, the number of crosslinks; and a host of other chemical features. The technology for study of these features includes Raman spectroscopy , Fourier transform infrared spectroscopy , and electron backscatter microscopy . For human studies, this also requires examination of iliac bone biopsies. It is important.