Chapter 35: Assessment of Musculoskeletal Function

The skeletal system features 206 bones categorized by shape—long, short, flat, and irregular—and is structurally maintained by three cellular components: osteoblasts for formation, osteoclasts for resorption, and osteocytes for maintenance. Bone is a dynamic tissue constantly undergoing remodeling, a simultaneous process of destruction and formation, influenced significantly by physical activity, adequate dietary intake of calcium (approximately 1000 to 1200 mg daily for adults) and Vitamin D, and hormonal regulators like parathyroid hormone (PTH) and calcitonin. When a fracture occurs, bone regeneration progresses through four distinct stages: hematoma formation, the inflammatory phase (soft callus bridge), the reparative phase (firm bony union), and the remodeling phase, which can extend over months to years. Joints, or articulations, are defined by their range of motion, ranging from immovable fibrous joints (synarthrosis) to freely movable synovial joints (diarthrosis), such as hinge and ball-and-socket joints. Muscle movement relies on the sliding of thick myosin and thin actin filaments within the sarcomeres, resulting in either isotonic contraction (muscle shortens) or isometric contraction (tension increases without length change). Nurses must recognize that disuse leads to muscle atrophy, while sustained resistance exercise can cause hypertrophy. Assessment begins with a detailed health history, noting the character and timing of pain—such as the dull, deep ache associated with bone pain or the worsening pain of osteoarthritis as the day progresses. Physical examination includes evaluating posture for spinal deformities like kyphosis, lordosis, and scoliosis; observing gait for smoothness or a limp; and assessing joints for range of motion, swelling (effusion), and grating sensations (crepitus) caused by irregular surfaces. A critical nursing intervention, especially in trauma cases, is the frequent assessment of neurovascular status, referred to as CMS (circulation, motion, sensation), to identify potential complications like compartment syndrome. Diagnostic procedures commonly utilized include standard x-rays, CT scans, and magnetic resonance imaging (MRI), noting that patients with most metal implants cannot undergo MRI due to the magnet. Other specialized tests are bone densitometry, commonly using DXA to measure bone mineral density (BMD) and predict fracture risk; arthroscopy for direct joint visualization; and electromyography (EMG) to assess muscle and nerve electrical potential, though this is contraindicated for patients on anticoagulants. Laboratory results, including serum calcium, phosphorus, alkaline phosphatase, and specific bone turnover markers, aid in confirming diagnosis and monitoring treatment efficacy.