SLR - January 2022 - Samantha M. Ralstin

Functional Outcomes of Arthroscopic OS Trigonum Excision in Adolescents

Reference: Chun L, Bastrom TP, Carroll AN, Edmonds EW. Functional Outcomes of Arthroscopic OS Trigonum Excision in Adolescents. J Pediatr Orthop. 2021 Nov-Dec 01;41(10):e904-e910. doi: 10.1097/BPO.0000000000001967. PMID: 34516473.

Level of Evidence: Level IV - Case Series

Scientific Literature Review

Reviewed By: Samantha M. Ralstin, DPM
Residency Program: John Peter Smith Hospital – Fort Worth, TX

Podiatric Relevance: The OS Trigonum is an accessory ossicle located on the posterolateral aspect of the talusand is present in 7-25 percent of the population. Inflammation of the o\OS trigonum can occur in patients with an acute ankle injury or those who undergo repeated hyper plantarflexion. Patients commonly present to a podiatrist’s office with complaints of posterior ankle pain, stiffness and swelling. The authors of this study aimed to report on the outcomes of arthroscopic resection of the OS Trigonum in adolescents as most literature reports the outcomes for adult patients. They hypothesized that adolescents would have successful outcomes similar to their adult counterparts in patient reported outcome scores.

Methods: This was a retrospective case series with 10 adolescents (12 ankles) between the ages of 12-18 years old diagnosed with a symptomatic OS trigonum or steida’s process based on the history, physical examination, and XR and MRI confirmation. Patients had to have failed conservative treatments such as rest, NSAIDs, activity modification, and home exercise programs. Patients underwent arthroscopic OS trigonum excision using a 3.0 millimeter burr. Outcomes were measured using the Foot and Ankle Ability Measure (FAAM) which has two subscales - Activities of Daily Living (ADL) and Sport, as well as the Single Assessment Numeric Evaluation (SANE) score. Scores greater than 80 was considered a good outcome. Authors also noted whether or not the patient had the ability to return to the same level of sport, and if the patients required additional foot and ankle surgery.

Results: All adolescents had a minimum two-year follow up. Out of the sample size 40 percent (4/10) of the patients reported suboptimal functional outcome scores (FAAM ADL, FAAM Sports or SANE < 80). These patients also discontinued sport due to continued ankle issues. Two patients also went on to have further ankle surgery. Complications of the procedure included CRPS and recurrent lateral ankle instability requiring further surgery.

Conclusions: This study is limited by its retrospective nature and small sample size, though reports worse functional outcomes for adolescents as compared to adults in the literature. In symptomatic os trigonum in adolescents, conservative treatment should be attempted first. If surgical excision is indicated, patients must be aware of the potential for continued pain in the ankle which can lead to decreased return to sport. 

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