Neuropathic joints, often called Charcot joints, are caused by loss of sensation in the joint so that it is severely damaged and disrupted. The Charcot foot is triggered by a combination of mechanical, vascular and biological factors which can lead to late diagnosis and incorrect treatment and eventually to destruction of the foot. The damage and disruption becomes so gross that the diagnosis of a neuropathic joint is easily made as the destruction progresses, both on clinical examination and X-rays, because no one who had sensation would tolerate such destruction of the joint.
Etiology; Any pathology that leads to loss of sensation in a joint may lead to a Charcot joint:
Classically, Charcot joints in the lower limb were most often the result of tabes dorsalis but that is much rarer these days. The most common cause is diabetic neuropathy and diabetes is increasing in prevalence.
In the upper limb the classical cause is Syringomyelia. Diabetic neuropathy is common in developed countries where diabetes is common but in developing countries, tabes dorsalis and leprosy account for a significant amount of neuropathic joints.
Investigations; A plain X-ray may show considerable disruption of the joint but, in early disease, the picture will resemble osteoarthritis. MRI scanning or radio nucleotide imaging may be valuable to differentiate soft tissue infection from osteomyelitis. Investigation may also be required to ascertain the cause of the neuropathy, or HbA1C testing to assess the control of the diabetes.
General measures ; The patient must be educated about the risk of damaging a joint that is devoid of pain.
An underlying disease may need to be treated. However, treatment of tertiary syphilis will not reverse tissue damage, although it will prevent further progression of that disease.Alcoholism or deficiency diseases may require attention.
The affected joint is initially immobilized in a cast. It may still permit ambulation but this should be limited for best results. If there is ulceration, the cast must be changed weekly for ulcer evaluation and debridement. Plain X-rays every month help evaluate progress. The cast is usually on for three to six months.
Pharmacological ; Bisphosphonates may be of value to help to heal the bones, particularly if caught in the acute phase.
Surgery ; Surgery is indicated for patients with severe or unstable deformities that, if untreated, will result in major amputations. Current surgical options include fusion and Achilles tendon lengthening. There is little strong evidence and consensus concerning the timing of treatment and use of different fixation methods.
Complications ; Fractures can occur without pain and the absence of treatment leads to deformity.
Neuropathic ulcer may occur and introduce infection. , Soft tissue infection or osteomyelitis may occur, Severe damage may require amputation.