The musculoskeletal system provides structural support, movement, and protection through the coordinated function of bones, joints, muscles, tendons, and ligaments. Bone homeostasis is maintained through continuous remodeling by osteoblasts (bone formation) and osteoclasts (bone resorption), regulated by parathyroid hormone, calcitonin, vitamin D, and mechanical stress (Wolff's law). Osteoporosis results from an imbalance favoring osteoclast activity, with trabecular bone loss exceeding cortical bone loss, particularly in postmenopausal women due to estrogen withdrawal removing its inhibitory effect on osteoclast differentiation and activity. Osteoarthritis involves progressive degradation of articular cartilage through metalloproteinase-mediated collagen and proteoglycan breakdown, subchondral bone remodeling, and synovial inflammation.