Os Trigonum Syndrome: A Cause of Posterior Ankle Pain.

Background: Os trigonum syndrome represents a cause of posterior ankle pain that is predominantly seen in athletes. The os trigonum ossicle forms from a secondary ossification center of the talus and is located at its posterior aspect in an interval between the posterior lip of the tibial plafond and calcaneus. The os trigonum ossicle is often an incidental finding and asymptomatic. However, repetitive plantarflexion and push-off maneuvers can cause symptoms and lead a patient to pursue orthopedic care.

Materials and methods: A review of the literature was conducted using the PubMed search engine with the following keywords: "os trigonum", "os trigonum ossicle", "os trigonum syndrome", "posterior ankle impingement", and "Stieda process".

Results: The pertinent anatomy, clinical presentation, diagnostic evaluation, and treatment of os trigonum syndrome were reviewed in the literature and are extensively discussed in this article.

Conclusion: Os trigonum syndrome represents a potential cause of posterior ankle pain that needs thorough evaluation regarding history, physical examination, and imaging. Once diagnosed, treatment ranges from conservative to surgical interventions depending on surgeon preference and specific case presentation. [Orthopedics. 2024;47(2):e67-e72.].