Repetitive Strain Injuries

Repetitive strain injuries (RSIs), cumulative trauma disorders, repetitive motion injuries, and work-related musculoskeletal disorders are synonymous terms describing a broad range of injuries resulting from excessive use of the spine, arm, hand, leg, or foot. In 1999, these injuries constituted 9 percent of the injuries in U.S. private industry that resulted in lost workdays. Wrist and hand problems accounted for the majority of the injuries and were the most costly and the most disabling. Some health care systems no longer accept a categorical diagnosis of RSI and insist on more specific diagnoses (e.g., tendonitis, neuritis, fascitis, myositis, carpal tunnel syndrome, thoracic outlet syndrome, cubital tunnel syndrome, degenerative arthritis, tendinosis, fibromyalgia, herniated disk, focal hand dystonia, neuropathic pain).

Healthy tissues constantly turn over, repair, and remodel, a maintenance function that requires good hydration, nutrition, and balanced loading and rest. Normally, structural tissue damage postinjury activates a cellular cascade to mediate the inflammation and initiate repair. However, in patients with chronic repetitive strain injuries, cumulative loading can lead to reduced perfusion (blood supply), poor axonal transport of peripheral nerves and excessive tissue inflammation, scarring, cell compression, matrix degeneration, muscle fiber loss, and cell death. This can lead to tissue discontinuity, biomechanical irritation, [Page 1382]pain, and change in the type and organization of the collagen in tendons and ligaments that alters strength, compliance, and flexibility. Thus, some individuals with RSIs can develop severe pain (with or without inflammation), others lose strength and endurance, and still others experience excessive fatigue, poor sensorimotor feedback, and painless loss of fine motor control, specifically at the work task (focal hand dystonia).

Repetitive microtrauma is usually classified by stage:

• Stage 1 = injury, probably inflammatory without pathological alterations
• Stage 2 = injury associated with pathological alterations
• Stage 3 = injury associated with structural failure (rupture)
• Stage 4 = injury meets criteria for stages 2 and 3 plus other changes, such as osseous calcification

This classification system focuses on the soft tissue response to injury without consideration of secondary, aberrant central nervous system degradation. Risk factors for RSI include occupation (e.g., heavy, stressful schedules of repetitive hand use that demand high levels of accuracy and progressive task difficulty), biomechanics (e.g., end range, forceful movements), patterns of use (e.g., rapid, stereotypical, near simultaneous, alternating movements), personal health (e.g., prior injury, disease status, hydration, fitness), psychosocial issues (e.g., emotional state, personality, perfectionism, anxiety, family support), and administrative factors (health care coverage, disability benefits, legal issues). These factors can affect the incidence of injury, the extent of the impairment, the potential for recovery, and the magnitude of disability.

Treatment initially includes rest from work, rest of the part, and anti-inflammatory medications. Ideally, intervention should also address prevention, including ergonomic modifications, decreased forceful repetition, aerobic and postural exercises, good hydration, and nutrition. If disabling signs and symptoms persist, intervention must factor in the stage of tissue pathology, the extent of tissue damage, the status of change in cortical function, and whether surgery, medications, therapeutic modalities, assistive devices, and/or therapeutic exercises, including learning-based sensorimotor training, are essential to recovery.