Differential Diagnosis for Foot Pain with No Flexion and Constant Swelling after Crush Injury

Single Most Likely Diagnosis

• Compartment Syndrome: This condition is highly likely given the symptoms of foot pain, no flexion, and constant swelling after a crush injury. Compartment syndrome occurs when pressure within the muscles builds to dangerous levels, decreasing blood flow and potentially leading to nerve damage. The symptoms described are classic for this condition, especially in the context of a crush injury.

Other Likely Diagnoses

• Fracture: A fracture, especially if it involves the bones of the foot or ankle, could explain the pain and swelling. The inability to flex the foot could be due to pain or instability from the fracture.
• Soft Tissue Injury: Significant soft tissue injury, including lacerations, contusions, or crush injuries to the muscles and tendons, could cause pain, swelling, and limited mobility.
• Nerve Damage: Direct injury to the nerves supplying the foot could result in pain, numbness, and weakness, including the inability to flex the foot.

Do Not Miss Diagnoses

• Infection (e.g., Cellulitis, Abscess): Infections can quickly become severe, especially in the setting of a crush injury that may have introduced bacteria into the wound. Signs might include increasing redness, warmth, swelling, and purulent discharge.
• Vascular Injury: Damage to the blood vessels could lead to ischemia or gangrene, which would be an emergency. Symptoms might include coldness, pallor, decreased pulses, and increased pain.
• Rhabdomyolysis: This is a serious syndrome due to direct or indirect muscle injury, which results in the death of muscle fibers and release of their contents into the bloodstream. This can lead to serious complications like kidney failure.

Rare Diagnoses

• Complex Regional Pain Syndrome (CRPS): A chronic pain condition that most often affects one of the arms, legs, hands, or feet after an injury or trauma. It's rare but could be considered if other diagnoses are ruled out and the patient presents with persistent, severe, and burning pain.
• Osteomyelitis: An infection of the bone, which could occur after a puncture wound that introduces bacteria into the bone. It's less common in the acute setting of a crush injury but should be considered if there's no improvement with treatment for other conditions.