Functional Outcomes of Arthroscopic OS Trigonum Excision in Adolescents

BACKGROUND: Outcomes of symptomatic os trigonum excision have been well described as a successful treatment in adults; however, the literature lacks information on standardized longer term functional outcomes in the pediatric population. HYPOTHESIS/PURPOSE: This study intends to report functional outcomes of arthroscopic os trigonum excision in adolescents who failed conservative management, with the hypothesis that these younger patients would have similar, successful outcomes of adult patients. METHODS: A retrospective study was performed on adolescents who underwent arthroscopic os trigonum excision at a single institution between 2011 and 2017. Patient demographic, clinical history, radiographic, and operative data were documented. Outcome measures included the Foot and Ankle Ability Measure (FAAM) score comprised of the Activities of Daily Living (ADL) and Sports subscales, Single Assessment Numeric Evaluation (SANE) score, ability to return to the same level of sport, and any additional foot/ankle surgery. RESULTS: Ten patients (12 ankles) met criteria with a mean age at surgery of 15.4 years (range, 12 to 18 years) and a mean follow-up of 6.5 years (range, 2.8 to 9.1 years). Mean FAAM ADL subscale, Sports subscale, and SANE scores were 91.0 ± 15.5, 76.3 ± 29.1, and 88.6 ± 15.1 respectively. A chronic duration of symptoms prior to surgery was associated with a lower FAAM Sports current level of function score (p=0.032). Four patients (40%) discontinued their sport due to continued ankle issues and reported significantly lower FAAM ADL subscale (p=0.01), Sports subscale (p<0.001), and SANE scores (p = 0.002). CONCLUSION: Os trigonum syndrome in the adolescent population may not have the same rate of success as that seen in adult athletes over the long term. However, if proven to be refractory to conservative measures and surgical intervention is indicated, patients and their families should be counseled about the risk for persistent ankle symptoms and the possibility that they may not be able to return to their previous level of sport.