Charcot Foot

Background

• Charcot neuropathic osteoarthropathy (Charcot joint) is a destructive joint disorder initiated by trauma to a neuropathic extremity. It can lead to dislocations and fractures of the foot. Diabetes, neuropathy, trauma, and metabolic abnormalities of the bone result in an acute localized inflammatory condition. The inflammatory response can permanently disrupt the bony architecture of the foot resulting in abnormal plantar pressures that are at risk for ulceration, osteomyelitis, and amputation.

• Charcot arthropathy can occur at any joint; however, it occurs most commonly in the lower extremity, at the foot and ankle in patients with diabetes.

Epidemeology

• Charcot joint develops in about 0.1% to 0.9% of people with diabetes.
• Majority of these patients will develop a foot ulceration.
• There is a significant association between elevated body mass index and Charcot arthropathy.

Pathophysiology

[Two commonly accepted theories]

• Neurotraumatic: The neuropathic area sustains multiple microtrauma leading to joint destruction.
• Neurovascular: Increased vascular flow due to neuropathy results in bone demineralization and bone resorption and destruction.

Clinical Features

[Varied presentations]: Acute Charcot Arthropathy may have the following features:

• Signs of inflammation.
• Profound unilateral swelling.
• Increase in local skin temperature.
• Erythema in the local area.
• Joint effusion.

Complications

• If not identified and treated properly charcot arthropathy may progress to marked joint deformity and skin ulceration over a bony prominence.
• The ulceration can result in a severe infection leading to amputation of the extremity.
• Foot collapse leading to the formation of a clubfoot.
• Rocker-bottom foot, in which collapse and inversion of the plantar arch may occur.
• Acute fracture and dislocation at the Lisfranc joint complex may follow insignificant or unrecognized trauma in patients with Charcot neuroarthropathy.
• Ossification of ligamentous structures, the formation of intra-articular and extra-articular exostoses, the collapse of the plantar arch.
• Development of osteomyelitis.

Differential Diagnosis

Foot infection

• Gout
• PsuedoGout
• Cellulitis
• Gangrene
  • Dry gangrene
  • Wet gangrene
• Trench foot
• Abscess
• Necrotizing soft tissue infections
  • Necrotizing fasciitis
  • Necrotizing myositis
  • Necrotizing cellulitis
• Osteomyelitis
• Diabetic foot infection
• Charcot Foot

Look A-Likes

• Peripheral artery disease
• Sporotrichosis
• Deep venous thrombosis

• Cellulitis
• Gangrene
  • Dry gangrene
  • Wet gangrene
• Trench foot
• Abscess
• Necrotizing soft tissue infections
  • Necrotizing fasciitis
  • Necrotizing myositis
  • Necrotizing cellulitis
• Osteomyelitis
• Diabetic foot infection
• Charcot Foot
• Wet-sock erosions

Work up

• CBC although it is non specific yet it may exclude infection.
• ESR
• Basic metabolic panel (Chem-7)
• HBA1C
• Alk Phosphatase
• Vit B-12 and folate
• Liver function tests or coagulation studies may suggest chronic alcoholism.
• Rapid plasma reagin (RPR) and fluorescent treponemal antibody–absorption (FTA-ABS) tests aid in the diagnosis of syphilis.