Neuropathic ArthritisDz

Synonyms: Charcot arthritis.

ICD-9 Code: 713.5 (diabetic, 250.6; syphilitic, 094.0; syringomyelic, 336.0).

Definition: Neuropathic joint disease (Charcot arthritis) is a chronic, exaggerated form of degenerative arthritis caused by loss of proprioception to involved joints.

Etiology: Loss of proprioception leads to repetitive trauma to unprotected joints and subsequent osteoarthritic change. Alternatively, sympathetic neurovascular reflexes may lead to hyperemia and active bone resorption. Common causes include diabetic neuropathy, tabes dorsalis (syphilis), and syringomyelia. Other causes include CPPD crystal deposition disease, recurrent intraarticular steroids, alcoholic neuropathy, amyloidosis, congenital indifference to pain, meningomyelocele, yaws, and spinal dysraphism. As many as one-third of patients have no demonstrable neurologic disorder.

Pathology: Pathologic changes are similar to those of OA. Pannus may be seen. There may be coincident and dramatic bony disintegration and new bone formation.

Demographics: Demography depends on the underlying condition. Neuroarthropathy occurs in 0.1% to 0.5% of diabetics, 4% to 10% of patients with tabes dorsalis, and >30% of those with syringomyelia.

Cardinal Findings: There may be large joint effusion, synovitis, joint instability, dislocation, and bony fragments with marked crepitus. Progression is variable. Two modes of presentation have been described:
1. Acute neuropathic arthropathy (atrophic/resorptive form) is rare and manifests as acute-onset inflammatory monarthritis of non–weight- bearing joints, with associated swelling, warmth, and pain. It may be misdiagnosed as infectious or crystal-induced arthritis.
2. Chronic neuropathic arthropathy is the more commonly recognized form. There is often an insidious chronic history of joint problems, usually involving weight-bearing joints. Joints are typically swollen from effusion or exaggerated osteoarthritic changes. Joints are usually not painful, and there is a loss of deep tendon reflexes.

Patterns of joint involvement differ according to etiology.
—Diabetic neuroarthropathy: The tarsometatarsal joint is commonly affected (less commonly, the ankle and metatarsophalangeal joint). Overlying soft tissue swelling and ulceration may be seen. The pain is often less than expected for the degree of deformity and osseous change.
—Tabes dorsalis: The knee and hip are most commonly affected, often with a genu varum deformity. A large, unstable knee may be accompanied by an Argyll Robertson pupil or an absent knee jerk reflex. Axial disease has been described.
—Syringomyelia: This degenerative condition affects the spinal cord, resulting in weakness and atrophy of the upper extremities with loss of reflexes and thermal anesthesia. Neuroarthropathy may affect the shoulders, elbows, and cervical spine.

Complications: Spontaneous fractures, dislocation, and osteomyelitis may occur.

Diagnostic Tests: Laboratory tests reflect the underlying disorder. Synovial fluid is either noninflammatory or hemorrhagic. Inflammatory effusions are uncommon and should prompt a search for other causes (e.g., crystal arthritis).

Imaging: During the acute phase, changes are nonspecific and include soft tissue swelling. Early changes resemble OA. Later, large osteophytes, new bone formation, bony fragmentation, dislocation, and subluxation may occur. Damage to periarticular structures may lead to malalignment and may contribute to subluxation and deformity. Bone scans show markedly abnormal uptake but are seldom required for diagnosis. Bone scan and MRI may be useful in diagnosing coexistent osteomyelitis or occult fracture.

Keys to Diagnosis: Diagnosis should be suspected in (a) diabetics with foot pain; (b) patients with exaggerated severe OA of the knee; (c) spontaneous fracture after little or no trauma; and (d) severe scoliosis with destructive radiographic changes (search for syringomyelia or syphilis).

Therapy: The underlying disorder should be treated, which may prevent further damage. Weight reduction, immobilization, and use of orthotics may be helpful. Pain medication and NSAIDs are not required in most. Intraarticular steroids are contraindicated.

Surgery: Arthrodesis and joint replacement have a high failure rate and are generally contraindicated. Amputation may rarely be necessary for advanced disease complicated by infection.

BIBLIOGRAPHY

Ellman MH. Neuropathic joint disease (Charcot joints). In: Koopman WJ, ed. Arthritis and allied conditions: a textbook of rheumatology, 13th ed. Baltimore: Williams & Wilkins, 1997:1641–1659.

Gupta R. A short history of neuropathic arthropathy. Clin Orthop 1993;296:43–49.PMID:8222448