Résumé : | The presence of an os sustentaculum bone is extremely rare. Given the scarcity of clinical literature reporting such a finding, the condition may be misdiagnosed as a fracture of the sustentaculum tali. We describe such an incident in a 16-year-old male athlete presenting for a recent ankle sprain with no other history of trauma or pain on the medial aspect of the ankle. The original computed tomographic scan reported a possible nonunion of a sustentaculum fracture, or peripherally corticated ossification in association with a possible talocalcaneal fibrocartilaginous coalition. Given no history of high-level trauma to the area, the clinical presentation, and the radiographic findings, the more likely diagnosis was confirmed to be an os sustentaculum. The goal of the authors of this article is to report such findings to raise awareness of a rare clinical presentation to avoid misdiagnosis.
The os sustentaculum (OS) is an accessory bone that can be found along the medial aspect of the ankle.1 This rare skeletal variant attaches to the talus at the sustentaculum tali, and can be bridged by means of the fibrocartilaginous or fibrous tissue. As currently reported, the prevalence of this condition is 0.3% of the population.2,3 Typically, the presence of an OS remains asymptomatic; however, symptoms may arise in cases where an osseous, cartilaginous, or fibrous coalition is present.4,5
The presence of an OS is scarcely reported in the literature. In this case report, we document not only this rare finding, but also its presence in an asymptomatic young athletic with suspicion of a fibrocartilaginous coalition. It is the goal of this study to present such a finding to increase awareness of its presence, and thereby decrease the chance of an inaccurate diagnosis in atraumatic cases. |