Trench foot

Background

• Considered a nonfreezing cold injury
  • Injury caused by cold exposure to tissue not resulting in freezing
• Develops slowly over hours-days when foot is exposed to cold/wet conditions
• Reversible injury may progress to irreversible injury
• Can cause gangrene or infection acutely, and cold intolerance and pain chronically
• Rarely seen in civilians, but a significant problem in military operations
• Also frequently seen in the homeless population, particularly during winter months (do not have ready access to clean/dry clothes or means to fully dry socks or shoes)

Clinical Features

• Initial signs and symptoms
  • Numbness and tingling
  • Pale, mottled, anesthetic, pulseless, and immobile foot
  • No changes will occur after initial rewarming
• Hours after rewarming
  • Hyperemic phase
  • Severe burning pain and reappearance of proximal sensation
• 2-3 days post treatment
  • Edema and bullae may form as perfusion returns
• Weeks later
  • Anesthesia persists and may be permanent
  • Tissue sloughing and gangrene may occur
• Months to years
  • Hyperhidrosis and cold sensitivity may persist
  • Some will have permanent disability

Differential Diagnosis

Foot infection

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

Look A-Likes

• Ingrown toenail
• Peripheral artery disease
• Sporotrichosis
• Deep venous thrombosis

Cold injuries

• Generalized
  • Hypothermia
• Freezing
  • Frostbite
• Non-freezing
  • Trench foot
  • Chilblains (Pernio)
  • Cold panniculitis
  • Cold urticaria
  • Polar thigh

Evaluation

• Clinical evaluation of the involved extremity. No specific laboratory or imaging is required.

Management

• Supportive care is mainstay of treatment
  • Keep feet clean, warm, dryly bandaged, elevated
  • Monitor for signs of infection
• Update tetanus
• Treat systemic hypothermia by rewarming
  • Do not actively rewarm extremities with isolated nonfreezing cold injury
• Vasodilators
  • Oral prostaglandins increase skin temperatures
• Prophylaxis
  • Keep warm, good boot fit, change out of wet socks

Disposition

• Mild cases can be discharged safely after being provided with strong education including frequenting changing of socks and keeping feet warm and dry
• Admission is generally required for observation and serial reexaminations of the extremity.

See Also

• Cold injuries