An ossicle around the medial malleolus is difficult to differentiate from an unfused ossification center, an avulsion fracture, and os subtibiale. Misdiagnosis can lead to inappropriate or unnecessary treatments. We describe a patient with a symptomatic ossicle of the medial malleolus in the left ankle that prevented participation in sports activities because of medial ankle pain. Plain radiography and computed tomography revealed a small ossicle associated with the anterior colliculus of the medial malleolus. Conservative treatment failed, and the patient underwent ankle arthroscopy. Instability of the ossicle was identified after the hypertrophic inflammatory synovium had been debrided. The ossicle was resected in a step-by-step manner with an arthroscopic shaver and grasper through the anteromedial accessary portal. The deltoid ligament sustained minimal damage after resection. The patient fully recovered and was able to return to sports activities 3 months after surgery. Arthroscopic resection of the ossicle at the medial malleolus requires no additional treatments of the deltoid ligament, effectively relieves symptoms, and enables the patient to return to full preinjury activities.
Level of Clinical Evidence: 4