Neuromuscular function in painful knee osteoarthritis.

Pain is a major cause of impaired mobility in elderly patients with chronic osteoarthritis (OA) of the knee. Central sensitization and impaired nociceptive inhibitory mechanisms have both been identified as contributing factors to heightened pain in this patient population. While central sensitization has been shown to produce enhanced pain responses and spread of pain to adjacent and remote body regions, conditioned pain modulation has also been shown to be adversely affected, and may be characteristic of those patients with chronic pain. Alterations of quantitative sensory testing measures have been demonstrated in patients with knee OA, and may serve as a clinical means of staging chronic musculoskeletal pain, including assessment of hyperalgesia and hypoesthesia. In addition, pain and altered somatosensation commonly associated with OA may be correlated with functional deficits.