Anteromedial Impingement in Chronic Lateral Ankle Instability: A Comparison of MRI and Arthroscopic Findings.

Introduction Chronic lateral ankle instability (CLAI) is a known complication of ankle sprains, most commonly involving injury to the anterior talofibular ligament (ATFL). Growing evidence has shown an association between anteromedial (AM) impingement and CLAI. The purpose of this paper is to compare magnetic resonance imaging (MRI) with arthroscopic findings for the incidence of AM impingement in CLAI. Methods A retrospective study was performed by analyzing the radiological and operative reports of all patients who underwent an arthroscopic Broström-Gould procedure for CLAI between 2021 and 2022 at Changi General Hospital, Singapore. All patients who had a pre-operative MRI ankle scan performed and mention of the presence or absence of AM impingement in the operative notes were included in this study. Patients with concomitant fractures or systemic conditions affecting the same ankle were excluded. Results Ninety-seven patients were included in this study, 65 males and 32 females; 6.2% (6 of 97) of patients had a suggestion of AM impingement based on MRI findings, and 77.3% (75 of 97) of patients were noted to have AM impingement based on arthroscopic findings. Conclusion There is a high incidence of AM impingement associated with CLAI. AM impingement is often missed based on MRI findings. Arthroscopic Broström should be considered to address both issues of AM impingement and CLAI in the same setting.