Clinical significance of the anteromedial talus osteophyte in anteromedial ankle impingement in chronic lateral ankle instability

PURPOSE: The aim of this study was to evaluate the relation between anteromedial ankle osteophytes (AMAO) and anteromedial ankle impingement (AMAI) in chronic lateral ankle instability (CLAI) through visualization and quantification. METHODS: Forty-three patients with unilateral CLAI between September 2018 and March 2020 accepted arthroscopic repair of an anterior talofibular ligament (ATFL) and were split into two groups: AMAI (AMAI including intraoperative AMAO resection) and pure CLAI (with AMAO but without AMAI, no AMAO resection). The AMAO protrusion lengths in each direction were measured and compared after all of the ankles were reconstructed. All patients were assessed preoperatively and at 2-year follow-up with ankle dorsiflexion, the American Orthopedic Foot and Ankle Society (AOFAS) ankle–hindfoot score, and visual analog scale (VAS) score. RESULTS: Intelligent analysis showed that a large extent of osteophytes was found at the dorsomedial surface of the talar neck in AMAI group. The upper and inner bound protrusion distances of AMAO in AMAI group were greater than in the pure CLAI group. There was no significant difference in anterior bound protrusion distance of AMAO between the two groups. Preoperatively, the ankle dorsiflexion of AMAI group (7.6 ± 1.4°) was considerably lower than that of pure CLAI group (22.4 ± 1.9°) (p < 0.001). When compared to the pure CLAI group, the AMAI group had a substantially worse AOFAS score (62.2 ± 6.7 vs 71.1 ± 9.1; p < 0.001) and VAS score (6.0 ± 1.0 vs 4.9 ± 0.8; p < 0.05). However, there was no significant difference in postoperative ankle dorsiflexion, AOFAS score, or VAS score between the two groups. CONCLUSION: AMAO is formed mostly on the dorsomedial surface of the talar neck in CLAI with AMAI, and the upper and inner bound protrusion lengths of AMAO were shown to be significantly correlated with the existence of AMAI in CLAI. Level of evidence IV.