Arthropathy may not develop until long after onset of the neurologic condition but can progress rapidly and lead to complete joint disorganization in a few months. In fully developed neurogenic arthropathy, hypertrophic or destructive changes may predominate, or findings may be mixed. The joint is swollen from bony overgrowth and massive synovial effusion. Deformity results from fracture with displacement or dislocation after destruction of articular surfaces, ligamentous laxity, and muscular hypotonia. Although most joints can be involved, the knee is affected as often as the sum of all other joints.
Distribution depends largely on the underlying disease.
Thus, tabes dorsalis affects the knee and hip, and diabetes mellitus affects the foot. Syringomyelia commonly affects the upper limb joints, especially the elbow and shoulder. The diagnosis should be considered in a patient with an appropriate neurologic disorder who develops a destructive but relatively painless arthropathy, usually several years after the onset of the underlying neurologic condition. X-rays show a swollen joint with synovial effusion and subluxation of the articular surfaces. Sclerosis of the bone ends is usual but may be absent in advanced or rapidly destructive disease.