Arthroscopic excision of the os trigonum: using the posteromedial portal safely

The os trigonum is an accessory ossicle that, though usually asymptomatic, can become a chronic source of pain, particularly in dancers and athletes. Surgical intervention is sometimes necessary, with arthroscopy having the theoretical advantages of less pain, inflammation, and scarring. Presented here is an example of chronic posterior ankle pain in an athlete successfully treated with arthroscopic os trigonum resection using posteromedial and posterolateral portals. We review the technical features and surgical technique of safe placement of the posteromedial portal and associated advantages.