Bipartite Os Trigonum Fracture: A Rare Variation with a Rare Fracture

This case report describes a bipartite os trigonum fracture in a 21-year-old female patient following a pedestrian traffic accident. The os trigonum, a rare accessory bone located posterolaterally in the talus, can sometimes lead to painful symptoms. In this case, a fracture of the bipartite os trigonum was identified, along with an anterior talofibular ligament rupture. Radiologic examinations revealed both the bipartite variation of the os trigonum and the associated fracture, with diagnosis confirmed through computed tomography (CT) and magnetic resonance imaging (MRI). Treatment involved a short leg splint and joint range-of-motion exercises, resulting in symptom improvement and functional recovery. This case highlights the importance of recognizing the rare occurrence of os trigonum fractures, particularly the even rarer bipartite variant, and underscores the significance of CT and MRI in a detailed diagnosis.