Differential Diagnosis for Inversion Ankle Sprain with Pain Proximal to Lateral Malleolus and No Pain to ATFL

• Single Most Likely Diagnosis
  • Peroneal Tendon Injury or Strain: This is the most likely diagnosis because the peroneal tendons run proximal to the lateral malleolus and can be injured during an inversion ankle sprain. Pain in this area without pain in the ATFL (anterior talofibular ligament) suggests that the injury might not be directly related to the common ligament sprains seen in inversion injuries.
• Other Likely Diagnoses
  • Cuboid or Peroneal Bone Contusion: These bones are located on the lateral side of the foot and can be injured during an inversion sprain, leading to pain proximal to the lateral malleolus.
  • Ligamentous Sprain Other Than ATFL: While the ATFL is commonly injured in inversion sprains, other ligaments such as the calcaneofibular ligament (CFL) or the posterior talofibular ligament (PTFL) could also be involved, especially if the mechanism of injury or the direction of force was slightly different.
• Do Not Miss Diagnoses
  • Fracture of the Fibula or Talus: Although less common, fractures in the area can occur with significant force and must be ruled out, especially if there's significant pain, swelling, or inability to bear weight.
  • Osteochondral Lesion of the Talus: This is a potentially serious condition where a piece of cartilage and bone in the talus becomes damaged. It can occur with ankle sprains and requires prompt diagnosis and treatment to prevent long-term damage.
• Rare Diagnoses
  • Peroneal Nerve Injury: Injury to the peroneal nerve, which runs near the peroneal tendons, could cause pain, numbness, or weakness in the area but is less common compared to other injuries.
  • Ganglion Cyst or Other Soft Tissue Mass: Although rare, a ganglion cyst or other soft tissue masses could cause pain and swelling in the area, mimicking an acute injury.