Arthroscopic versus posterior endoscopic excision of a symptomatic os trigonum: a retrospective cohort study.

BACKGROUND: Both subtalar arthroscopic and posterior endoscopic techniques are used to treat posterior ankle impingement syndrome (PAIS). However, there have been no studies comparing the 2 procedures.

HYPOTHESIS: Both arthroscopic and endoscopic excisions of the os trigonum are safe and effective in treating PAIS.

STUDY DESIGN: Cohort study; Level of evidence, 3.

METHODS: Twenty-eight patients were treated with excision of the os trigonum either by an arthroscopic (16 patients) or endoscopic (12 patients) technique. The mean patient age was 29.8 years (range, 17-55 years), and the mean follow-up period was 30 months (range, 18-58 months). Preoperative and postoperative visual analog scale (VAS) score for pain, American Orthopaedic Foot and Ankle Society (AOFAS) score, and Maryland Foot Score (MFS) were used to analyze the functional results. Duration of surgery, time to return to sports (RTS), and patient satisfaction were evaluated as well. The size of the os trigonum was measured using T1-weighted sagittal magnetic resonance imaging (MRI). The clinical and MRI results were compared between the 2 groups.

RESULTS: The VAS score, AOFAS score, and MFS for both the arthroscopic group (preoperative: 6.3, 63.8, and 61.5, respectively; postoperative: 1.2, 89.9, and 89.6, respectively) and endoscopic group (preoperative: 6.7, 64.8, and 62.5, respectively; postoperative: 1.2, 89.9, and 88.4, respectively) improved significantly (P < .01). The mean surgery and RTS times were 39.4 minutes and 7.5 weeks in the arthroscopic group and 34.8 minutes and 8.0 weeks in the endoscopic group, respectively (P > .05). All patients were satisfied with the results. There were no significant differences between the 2 groups in the preoperative and postoperative VAS score, AOFAS score, or MFS (P > .05). The mean size of the os trigonum was 11.1 × 8.8 mm(2) in the arthroscopic group and 12.6 × 10.4 mm(2) in the endoscopic group, and the difference was significant (P < .05). Two patients underwent both arthroscopic and endoscopic procedures because of technical difficulty in removing the large os trigonum arthroscopically.

CONCLUSION: Both arthroscopic and posterior endoscopic excisions of the os trigonum were safe and effective in treating PAIS. The arthroscopic procedure was more demanding, especially in cases of a large os trigonum. The posterior endoscopic approach had the advantage of addressing problems in the posterior ankle joint and allowed a more extensive release of the flexor hallucis longus.