Os Trigonum

The os trigonum is the largest and most common accessory ossicle in the foot and ankle region and it usually becomes symptomatic in active individuals, especially in ballet dancers and soccer players. Bony presence of an os trigonum or an elongated posterolateral tubercle are the most frequent causes of posterior ankle impingement. The diagnosis is based on clinical history, with careful description of the physical activities that trigger symptomatology, physical examination and image studies. Best outcomes are achieved with minimal invasive surgical treatment, which involves the excision of the bony fragment through endoscopic or arthroscopic techniques.