Differential Diagnosis for Lower Leg Injury

The patient's symptoms and test results suggest a range of possible diagnoses. Here's a categorized list of potential causes:

• Single most likely diagnosis

  • Cellulitis or soft tissue injury: Given the history of trauma (board impact), minimal pain, swelling that improves with elevation but worsens with walking and gravity, and the absence of significant bruising or DVT, a soft tissue injury or cellulitis is the most plausible explanation. The negative X-ray and ultrasound for DVT further support this diagnosis, as they rule out more serious conditions like fractures and blood clots.

• Other Likely diagnoses

  • Hematoma: Although there's no significant bruising, a hematoma could still be present, especially if it's deep or not yet fully developed. The swelling and worsening symptoms with gravity could be indicative of a hematoma.
  • Lymphatic injury or obstruction: Trauma to the lower leg could potentially damage lymphatic vessels, leading to swelling that worsens with activity and improves with elevation.
  • Muscle strain or contusion: Direct trauma from the board could result in muscle strain or contusion, which would cause pain, swelling, and worsening symptoms with activity.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

  • Compartment syndrome: Although less likely given the minimal pain and improvement with elevation, compartment syndrome is a medical emergency that requires prompt intervention. It can occur after trauma and is characterized by increased pressure within a muscle compartment, leading to nerve and muscle damage.
  • Osteomyelitis or septic arthritis: Infection of the bone or joint is a rare but potentially life-threatening complication of trauma. While the patient's symptoms do not strongly suggest this, it's essential to consider and monitor for signs of infection, such as increasing pain, redness, or fever.

• Rare diagnoses

  • Nerve injury or neuropathy: Direct trauma to the nerves in the lower leg could result in nerve injury or neuropathy, leading to pain, swelling, and sensory changes.
  • Vascular injury (arterial): Although the ultrasound ruled out DVT, an arterial injury is still possible, especially if the trauma was severe. This would require further investigation, such as angiography, to diagnose.