Neuropathic Joints (Charcot's Joints)

Arthropathia neurotica, neuropathic arthritis/arthropathy, tabetic osteoarthropathy.

Neuropathic joints, often called Charcot joints, are caused by loss of sensation in the joint so that it is severely damaged and disrupted. The damage and disruption is often so gross that the diagnosis of a neuropathic joint is easily made, both on clinical examination and x-ray, because no one who had sensation would tolerate such destruction of the joint.

However, the concept that the patient without sensation smashes the joint with impunity may be an oversimplification as there may be problems related to autonomic neuropathy, poor blood supply and mismatch of bone destruction and synthesis.¹

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 very much rarer these days.
• Nowadays the commonest cause is diabetic neuropathy and diabetes is increasing in prevalence.
• In the upper limb the classical cause is syringomyelia.

A neuropathic type joint has been reported with frequent and repeated steroid injections into a joint but this is rare and it requires perseverance with injections at a frequency and for a duration that few would contemplate.²

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. Charcot joints occur in 10-20% of patients with tabes dorsalis and in 20-25% of patients with syringomyelia.

Presentation is variable, depending upon the stage of the disease.

• There may be swelling
• There may be distortion
• There may be loss of function
• Pain is present in 75% but, considering the state of the joint, the clinician will be surprised that there is not considerably more pain.

• A joint may be severely damaged by trauma but there will be a history of trauma and the patient will complain of much pain unless the trauma damaged nerves leading to anaesthesia of the joint.
• The lack of pain in a Charcot joint may resemble "la belle indifference" of hysteria but other aspects would point to a psychological problem.
• Osteomyelitis may well coexist with a Charcot joint.

• A plain x-ray may show considerable disruption of the joint but in early disease the picture will resemble osteoarthritis.
• MRI scanning or radionucleotide 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 to assess the control of the diabetes.

Diabetes, tabes dorsalis, syringomyelia and leprosy have been mentioned. The differential diagnosis of peripheral neuropathy includes alcoholism, vitamin B1 and vitamin B12 deficiency.

• 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.
  • Treatment of tertiary syphilis will not reverse tissue damage but it will prevent further progression of that disease.
  • Alcoholism or deficiency diseases may require attention.
  • Good control of diabetes is essential to prevent progression of the neuropathy.
• There is a suggestion that biphosphonates may be of value to help heal the bones³ but there is a lack of further trials giving promising results.
• The affected joint is initially immobilized in a cast. They 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 3 to 6 months.
• After removing the cast, protection of the joint for the rest of the patient's life is essential. This requires patient education and foot care by a podiatrist. Various types of braces may protect the foot.
• Various types of protective shoes may be required. If ulcers are present, a rocker-bottom sole can be used. Also, Plastic inserts can be used for anaesthetic feet. A less intense regime may be permitted after 6-24 months, depending upon clinical progress but special footwear is required for life.
• The total process of healing usually takes 1-2 years. Preventing further injury, noting temperature changes, checking feet every day, reporting trauma, and receiving professional footcare also are important aspects of treatment.
• The basis of treatment is medical but surgery may also be required. In a study of diabetic surgery in some form was needed in 25%.⁴

• Fractures can occur without pain and the absence of treatment leads to deformity.
• Neuropathic ulcer may occur and introduce infection.
• Soft tissue infection of osteomyelitis may occur.
• Severe damage may even require amputation.⁵

A good prognosis depends upon early recognition of the problem and effective management that includes patient education.⁵

• In western societies the most important form of prevention would be the prevention of type 2 diabetes and the control of existing diabetes. Diabetic clinics facilitate early detection of problems.
• In the developing world, prevention of syphilis and leprosy is still important.

Jean-Martin Charcot was a French neurologist who was born in Paris in 1825 and died in 1893. He was one of the founders of the Salpetrière hospital in Paris that became of world centre of excellence for neurology. He is regarded as the father of neurology and has 15 medical eponyms, not all of them related to neurology. He described neuropathic joints due to syphilis in 1868⁶ but the earliest recorded description would appear to be from William Musgrave in 1703.⁷