Charcot joint--neurogenic arthropathy--is a condition that occurs when nerve injury leads to destruction of a joint. There is bilateral involvement in between 9 percent and 35 percent of cases according to the "AAOS Comprehensive Orthopaedic Review." The anatomic location of the arthropathy determines the prognosis and treatment for the patient.
Causes
There are two main theories on how joint destruction occurs. The neurotraumatic theory states that mechanical trauma in the setting of loss of pain and other sensation leads to bone destruction. The neurovascular theory involves the combination of trauma and vascular changes that lead to decreased bone mineral density or osteopenia . The common foot and ankle joints involves are the tarsometatarsal and naviculocuneiform joints; subtalar, talonavicular, or calcaneocuboid joint; tibiotalar joint.
Conditions
The neuropathic disorders that can lead to Charcot joint include tabes dorsalis or neurosyphilis, diabetic neuropathy, syringomyelia, spinal cord injury, pernicious anemia, leprosy or Hansen's disease, and perhipheral nerve injury. Numerous hydrocortisone injections into a joint can also precipitate joint destruction leading to the Charcot joint.
Symptoms
The joint may become enlarged with swelling, but remain painless. On physical exam, the joint may be unstable. The Charcot joint is often confused clinically with an infected joint, however in Charcot joint there is no significant fever or elevation in white blood cell count.
Imaging
X-rays can reveal joint erosion, loose bodies, and/or osteophytes or extra bone fragments. Bone scans can be misleading. MRI tends to be the best modality to see soft-tissue swelling, but it may be difficult to differentiate infection from Charcot joint.
Treatment
The treatment of the Charcot joint is primarily aimed at treating the underlying condition. Mechanical devices can also be used to decrease the stress of weight bearing on the extremity and prevent further mechanical injury. This total contact casting (TCC) is the gold standard of non-surgical treatment with a success rate of up approximately 75 percent, according to the "AAOS Comprehensive Orthopaedic Review." Surgery can be done to attempt to reconstruct the joint, however amputation of the joint sometimes has to occur.
References
- "AAOS Comprehensive Orthopaedic Review"; Dr. Jay Lieberman (editor); 2008.
- "Wheeless' Textbook of Orthopaedics": Charcot Changes in the Diabetic Foot and Ankle
