What is Charcot foot?

Charcot Foot: Definition and Clinical Implications

Charcot foot, also known as Charcot neuro-osteoarthropathy (CNO), is an inflammatory process occurring in persons with peripheral polyneuropathy that results in injury to bones, joints, and soft tissues, most commonly affecting the foot and ankle in people with diabetes mellitus, leading to distortion of foot architecture and potential deformity through fractures and dislocations.1

Pathophysiology and Epidemiology

• CNO occurs primarily in people with diabetes mellitus with peripheral neuropathy, though it can affect anyone with peripheral neuropathy 1
• The condition involves an inflammatory process that causes progressive bone and joint destruction in the presence of impaired pain perception 1, 2
• The true prevalence is estimated at approximately 0.3% of patients with diabetes mellitus, suggesting around 1.6 million people worldwide are affected with an annual incidence of 160,000 new cases 1
• The soft tissue and osseous injury results in distortion of foot architecture through fractures, dislocations, and fracture-dislocations 1

Clinical Presentation

• Patients typically present with a warm, erythematous, edematous foot with intact skin 1
• Due to peripheral neuropathy, patients often do not perceive the onset of joint destruction, making early diagnosis challenging 2
• The condition is frequently misdiagnosed as infection, osteoarthritis, gout, or inflammatory arthropathy 2, 3
• Progressive deformity leads to altered weight-bearing patterns that can result in ulceration and infection 1

Diagnosis

• Diagnosis is primarily clinical but should be supported by imaging 1
• Serial temperature measurements between affected and unaffected limbs help monitor disease activity 1
• Plain radiographs are the initial imaging modality of choice 1
• MRI can be useful for early diagnosis when radiographs are normal 1
• Blood tests including CRP, ESR, and white blood count are not recommended for diagnosis 1

Management

• The primary treatment for active Charcot neuro-osteoarthropathy is immobilization and offloading using a non-removable knee-high device, preferably a total contact cast, which should be initiated as soon as the diagnosis is considered 1
• A knee-high walker rendered non-removable can be considered as a second choice 1
• Removable knee-high devices should only be used when non-removable options are contraindicated or not tolerated 1
• Below-ankle offloading devices should not be used due to inadequate immobilization 1
• Assistive devices are recommended to reduce weight-bearing on the affected limb 1
• Pharmacological treatments including bisphosphonates (alendronate, pamidronate, zoledronate), calcitonin, PTH, methylprednisolone, or denosumab are not recommended 1
• Vitamin D and calcium supplementation should be considered during fracture healing 1
• Surgical intervention may be necessary in cases with joint instability, significant deformity, or pain that cannot be managed with conservative treatment 1

Prevention of Reactivation and Complications

• After remission, appropriate footwear and orthoses are essential to prevent reactivation 1
• For patients with deformity or joint instability, below-knee customized devices are recommended 1
• Charcot foot significantly impacts quality of life and increases mortality risk, with a pooled 5-year mortality rate of 29% 1
• Deformities from Charcot foot increase the risk of ulceration and infection, which can lead to amputation 1
• Studies show a 6-12 times increased risk of major amputation in individuals with foot ulcers resulting from Charcot deformity 1

Common Pitfalls in Management

• Delayed diagnosis due to absence of pain from peripheral neuropathy 2, 4
• Misdiagnosis as infection, particularly in cases with erythema and increased temperature 2, 3
• Inadequate offloading or use of inappropriate devices 1
• Failure to monitor disease activity with regular temperature measurements 1
• Overlooking the need for appropriate footwear after remission to prevent reactivation 1