A 62-year-old man with type 2 diabetes for 15 years presents with history of erythematous, hot, swollen right foot for 2 weeks. Picture shown below:
He is on multiple medications for management of his diabetes, but it is not successfully controlled. The patient does not recall any trauma to the foot. Three days ago, he noticed pain in his foot. He denies fever or chills.
The radiograph of his foot shows midfoot osteopenia, an early sign of acute Charcot arthropathy.
Charcot arthropathy is an uncommon foot complication in patients with neuropathy. Patients often present with pain, swelling, and erythema, similar to the presentation with a foot infection. Patients
may have a rockerbottom foot deformity. Radiographs confirm the diagnosis.
The incidence of Charcot arthropathy in diabetes ranges from 0.1% to 5%.
Pathophysiology: Charcot arthropathy is a gradual destruction of the joint in patients with neurosensory loss, most commonly seen in patients with diabetic neuropathy. The pathogenesis is unknown but the proposed theories include:
• Neurotraumatic theory—Following sensory-motor neuropathy, the resulting sensory loss and muscle imbalance induces abnormal stress in the bones and joints of the affected limb, leading to bone destruction.
• Neurovascular theory—Following the development of autonomic neuropathy there is an increased blood flow to the extremity, resulting in osteopenia from a mismatch in bone reabsorption and synthesis.
• Stretching of the ligaments because of joint effusion may lead to joint subluxation.
• It is most likely that Charcot arthropathy involves all of the above mechanisms together.
Risk Factors Include:
• Advanced peripheral neuropathy.
• Micro- or macrotrauma.
Clinical Features: include:
• Red, hot, swollen foot
• Even with neurosensory loss, 71% of patients present with the chief complaint of pain.
• Rockerbottom foot deformity is a classic finding of this entity.
• Patients may present with an open wound in the plantar aspect of the foot, which may complicate the diagnosis between Charcot arthropathy and infection.
Diagnosis: The diagnosis of Charcot arthropathy is suspected based on the presentation and confirmed with imaging.
Radiographs are imperative for diagnosis.
• Arch collapse within the joints of the midfoot (tarsometatarsal joints).
• Erosions and cystic degeneration of the tarsometatarsal joints in Charcot arthropathy may also be present.
• Bone scan and MRI may be ordered when infection is suspected, but are often inconclusive as cellulitis and osteomyelitis have similar findings.
Culture and Biopsy: If osteomyelitis is suspected, bone cultures and bone biopsy are recommended. Cultures need to be taken during the bone biopsy so that the suspected infected bone can be visualized for accurate sampling. Send cultures for aerobic and anaerobic cultures as well as for acid-fast bacilli.
Differential Diagnosis Include:
• Infections, including cellulitis and osteomyelitis, should be considered and treated if present.
• Gouty arthropathy of the foot or ankle can resemble a Charcot foot'
• Acute trauma to the foot can cause swelling and erythema, butshould be easy to distinguish by the history.
• Deep venous thrombosis in the leg will generally cause swelling that extends above the ankle.
• Offloading of pressure from the foot is the standard of care. The total contact cast is most effective, and it covers the toes for protection. Other methods that are used include the removable cast boot, crutches, and the wheelchair.
• Diabetic shoes should not be used as offloading devices for Charcot arthropathy.
• Skin temperature assessment with infrared thermometry has been demonstrated to be successful in monitoring improvement.
• Prevention of rockerbottom deformities, plantar ulcers, and amputations is the major goal of the treatment. Untreated Charcot foot may lead to a rockerbottom foot, which in turn leads to increased plantar pressure in the neuropathic foot. This cascade will lead to an ulceration and possible amputation.
• The bones will take approximately 4 to 5 months to heal in presence of neuropathy.
• Oral antibiotics are not indicated unless infection is suspected.
• If deformity develops, custom-molded shoes and insoles must be ordered to prevent plantar ulcers that can lead to amputation.
• If the foot develops instability at the fracture sites, surgical reconstruction may be required