Differential Diagnosis for Left Ankle Pain
Single Most Likely Diagnosis
- Peroneal Tendinopathy: This condition is characterized by inflammation or degeneration of the peroneal tendons, which run along the lateral aspect of the ankle and behind the lateral malleolus. The pain pattern described, radiating up the fibula, is consistent with peroneal tendinopathy. The absence of abnormalities on ultrasound and X-ray does not rule out this diagnosis, as tendinopathy can be difficult to detect with these imaging modalities.
Other Likely Diagnoses
- Lateral Ankle Impingement: This condition occurs when there is compression of the soft tissues (such as tendons and ligaments) between the lateral malleolus and the fibula, leading to pain and inflammation. The location of the pain and the absence of a clear injury or abnormality on imaging make this a plausible diagnosis.
- Anterior Talofibular Ligament (ATFL) Strain: Although the patient reports no injury, minor strains or overuse injuries can cause ATFL strain without a significant traumatic event. The pain over the ATFL and radiation up the fibula could be consistent with this diagnosis.
- Peroneal Nerve Irritation: Irritation or compression of the peroneal nerve, which runs along the lateral aspect of the leg and ankle, can cause pain in the area described. This could be due to various factors, including overuse, poor footwear, or anatomical variations.
Do Not Miss Diagnoses
- Osteoid Osteoma: A small, benign bone tumor that can cause severe pain, often worse at night and relieved by NSAIDs. Although rare, missing this diagnosis could lead to prolonged pain and disability. Advanced imaging like MRI or CT might be necessary for diagnosis.
- Stress Fracture: Despite the normal X-ray, a stress fracture, especially in the fibula, could present with pain in the described location. Stress fractures can be occult on initial X-rays and may require further imaging like MRI or a bone scan for diagnosis.
- Infection or Osteomyelitis: Although less likely without systemic symptoms or a clear source of infection, it's crucial not to miss infections around the ankle, as they can lead to severe consequences if not promptly treated.
Rare Diagnoses
- Erythromelalgia: A rare disorder characterized by burning pain, heat, and redness in the hands and feet. It could potentially cause pain in the ankle area, although it's much less common.
- Complex Regional Pain Syndrome (CRPS): A condition characterized by chronic pain, inflammation, and hypersensitivity after an injury or trauma. While the patient reports no injury, CRPS can sometimes occur without a clear precipitant, and the pain pattern can be diffuse and not strictly limited to the area of initial injury.