Outcomes of open and endoscopic excision of a symptomatic os trigonum in athletes: a systematic review with exploratory analysis of prognostic factors

BACKGROUND: A symptomatic os trigonum causes posterior ankle impingement in athletes and is excised when conservative treatment fails. Previous syntheses have pooled mean outcomes across mixed populations, and poor outcomes have not been defined consistently. METHODS: Six databases were searched for open or endoscopic os trigonum excision in athletes, following PRISMA 2020 and SWiM. Techniques were compared within comparative studies, with supplementary pooling. A composite poor-outcome profile and eight candidate factors were examined at study-arm level. RESULTS: Thirteen studies (17 arms, 440 participants) were included. Failure to return to prior level was uncommon (9 of 438; 0-6.2% by arm). In the randomised trial, return to prior sport level was 4.4 weeks faster after endoscopic excision (95% confidence interval [CI] 2.7-6.1); pooling two further non-randomised studies with imputed SDs gave 4.9 weeks (95% CI 3.3-6.6). Trial complications occurred in 1 of 26 endoscopic and 6 of 26 open patients (odds ratio 7.50, 95% CI 0.83-67.49); the two-study pooled odds ratio was 5.59 (95% CI 1.10-28.35) from 10 events. Both nerve injuries described as permanent followed open surgery. The composite depended on arm size and threshold choice, and five of eight candidate factors could not be tested. CONCLUSION: Poor outcomes are uncommon after either approach. Low-certainty evidence suggests faster return to sport after endoscopic excision; complication evidence is of very low certainty, though no nerve injury described as permanent followed endoscopic excision. A consensus definition of return to sport is needed.