Differential Diagnosis

• Single most likely diagnosis
  • Ankle sprain: This is the most likely diagnosis given the thickened ATFL (Anterior Talofibular Ligament) and CFL (Calcaneofibular Ligament), which are common findings in ankle sprains. The presence of focal synovitis at the talonavicular joint also supports this diagnosis, as it can be a secondary finding due to altered biomechanics or direct trauma.
• Other Likely diagnoses
  • Ankle instability: Repeated ankle sprains can lead to chronic instability, which may present with similar findings. The thickened ligaments could be a result of chronic inflammation and scarring.
  • Talonavicular joint arthritis: The focal synovitis at the talonavicular joint could be an early sign of arthritis, especially if the patient has a history of trauma or repetitive stress to the joint.
  • Sinus tarsi syndrome: This condition involves inflammation of the sinus tarsi, a small canal in the foot, and can present with similar symptoms and findings, including synovitis and ligament thickening.
• Do Not Miss diagnoses
  • Osteochondral lesion of the talus: A potentially serious condition that could be masked by the symptoms of an ankle sprain. It's crucial to rule out this diagnosis, as it may require surgical intervention.
  • Fracture or avulsion injury: Although the initial findings suggest a sprain, it's essential to consider the possibility of a fracture or avulsion injury, especially if the patient has a history of significant trauma.
• Rare diagnoses
  • coalition of the subtalar joint: An abnormal connection between the bones of the subtalar joint, which could present with similar symptoms and findings, including synovitis and ligament thickening.
  • Inflammatory arthropathy (e.g., rheumatoid arthritis): Although less likely, it's essential to consider inflammatory arthropathies, especially if the patient has a history of systemic symptoms or multiple joint involvement.