- Last Update On : 2013-01-27
Bone remodeling allows for bone growth, bone repair and elimination of microfractures. Osteoclasts resorb old bone, while osteoblasts synthesize new protein, known as osteoid. Within several months, osteoid becomes calcified. After the age of 40 years, bone destruction begins to exceed formation, leading to osteoporosis. For every 10% of bone that is lost, the risk of fracture doubles.
The medications most commonly used to treat osteoporosis are estrogen, calcitonin and biphosphonates (etidronate, alendronate, risedronate). Their mechanism of action is to inhibit osteoclastic activity and decrease bone resorption. Treatment with biphosphonates must be continuously monitored because overdosage can eventually weaken bone.
More than 90% of the osteoid matrix of bone consists of type I collagen. Noncollagenous proteins, such as osteocalcin, comprise the remaining 10%. Type 1 collagen is synthesized as procollagen precursor molecules. Prior to insertion into the osteoid m