To report the clinical outcomes of arthroscopic excision for a symptomatic os trigonum initially viewing through the posteromedial ankle portal with the motorized instrument in the posterolateral portal.

A retrospective review of a consecutive series of patients with symptomatic os trigonum failing nonoperative management and treated with arthroscopic excision was performed. Demographic data, clinical data, American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot scores, and Single Assessment Numeric Evaluation scores were obtained. Any complications and the time required to return to sports or full activities were recorded.

Twenty-four patients with an arthroscopic excision of a symptomatic os trigonum were included. There were 13 male and 11 female patients. The average age was 36.7 ± 17 years. Twenty-one isolated os trigonum excisions and 3 excisions combined with other procedures were studied. At a mean follow-up of 26 months (range, 24 to 31 months), average preoperative AOFAS scores significantly improved from 55.3 to 92.3 postoperatively (P < .0001). The preoperative AOFAS function component improved from 17.1 to 33.8 (P < .0001). The mean postoperative Single Assessment Numeric Evaluation score was 90. Patients reported full activity at an average of 1.5 months with no limitations at an average of 7.8 months after surgery. The only complication was a posterior tibial nerve calcaneal branch neurapraxia.

Arthroscopic excision in the prone position without traction of a symptomatic os trigonum viewing initially through the posteromedial portal with a high-speed burr in the posterolateral portal resulted in significantly improved AOFAS scores with a single transient neurapraxia in 24 patients. Patients returned to their normal daily activities without limitations at an average of 1.5 months.

Level IV, therapeutic case series.