Gouty os trigonum tarsi: case report.

Os trigonum tarsi is found in 7% of the world adult population. However, it rarely causes symptoms. The majority of patients with os trigonum tarsi are found incidentally. This condition is often found in ballet dancers, javelin throwers and soccer players. It rarely produces symptoms in normally active adults. The etiology of os trigonum syndrome is impingement of an unfused ossicle or a fractured posterior lateral tubercle of talus over the posterior rim of tibial plafond. We present a case of os trigonum syndrome in a young man. His posterior heel pain was due to tophaceous gout around the os trigonum tarsi, instead of the common pathogenesis of repeated hyperflexion of the ankle joint. Pictures of the specimen showed marked giant cell reaction which resulted in pseudotumor formation. We reviewed the clinical characteristics of os trigonum tarsi and gout and present the treatment of our patient.