Differential Diagnosis for Swelling and Tenderness in the Exterior Ankle with an Urge to Tense Muscles

• Single Most Likely Diagnosis
  • Ankle Sprain: This is the most common injury causing swelling and tenderness in the exterior ankle. The urge to tense muscles could be a response to pain or instability, which is typical in ankle sprains.
• Other Likely Diagnoses
  • Peroneal Tendinitis: Inflammation of the peroneal tendons, which run along the outside of the ankle, can cause swelling, tenderness, and pain, especially with muscle tension.
  • Lateral Ankle Impingement: This condition involves soft tissue impingement in the lateral gutter of the ankle, leading to pain and swelling on the outside of the ankle, which could provoke muscle tension.
  • Stress Fracture: A small crack in one of the bones in the ankle can cause pain, swelling, and tenderness, particularly with weight-bearing activities, and might lead to muscle tension due to pain.
• Do Not Miss Diagnoses
  • Osteochondral Lesion of the Talus (OLT): Although less common, an OLT is a potentially serious condition where a piece of cartilage and bone in the talus (ankle bone) becomes damaged. It requires prompt diagnosis to prevent further damage.
  • Compartment Syndrome: A condition where pressure within the muscle compartments increases, leading to inadequate blood supply. It's a medical emergency that can cause severe pain, swelling, and muscle tension.
  • Infection (Cellulitis or Abscess): Infections in the soft tissues around the ankle can cause swelling, redness, warmth, and pain, and it's crucial to diagnose and treat them promptly to avoid serious complications.
• Rare Diagnoses
  • Erythromelalgia: A rare disorder characterized by burning pain, heat, and redness in the hands and feet, which could potentially involve the ankle area and cause swelling and muscle tension.
  • 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, which could lead to swelling, tenderness, and muscle tension in the affected area.
  • Tumor (Benign or Malignant): Although rare, tumors around the ankle can cause swelling, pain, and muscle tension due to the mass effect or invasion into surrounding tissues.