Displaced Distal Fibular Epiphysis in a Child: A Clinical and Radiological Evaluation of a Rare Injury Hidden From the Initial Radiological Examination

Fractures of the lateral malleolus are common in children. Isolated lesions of the distal fibula physis commonly comprise nondisplaced or minimally displaced fractures. An isolated, completely displaced epiphysiolisthesis of the distal fibula is an extremely rare lesion. This study introduces the case of an 11-year-old boy presenting an extremely rare lesion of an isolated, completely displaced distal fibular epiphysis that was difficult to diagnose on X-ray. Initial radiographic examination of the injured ankle showed normal configuration of the tibia and fibula on AP projection, with soft tissue swelling of the lateral malleolus. On the lateral projection, the talus completely covered the distal fibular epiphysis, and particular attention was required to reveal the complete displacement of the distal fibular epiphysis. A CT scan confirmed the diagnosis of an isolated, completely displaced distal fibular epiphysiolisthesis. The patient was treated with a closed reduction and made an uneventful recovery. This report highlights the importance of accurate clinical and radiological assessment of an isolated, completely displaced, distal fibular epiphysiolisthesis.