Approximately two‐thirds of adolescent male soccer players had increased lateral ankle laxity with functional ankle impairments

Purpose The primary purpose of this study was to evaluate the prevalence of increased lateral ankle laxity (ILAL) in adolescent male soccer players. The secondary purpose was to investigate functional ankle impairments and muscle strengths related to chronic lateral ankle instability (CLAI). Methods The anterior talofibular ligament (ATFL) lengths of adolescent male soccer players were measured in the stress and non‐stress positions using ultrasonography. The ATFL ratio, the ratio of stress ATFL length to non‐stress ATFL length, was calculated as an indicator of lateral ankle laxity. The Cumberland Ankle Instability Tool (CAIT), Ankle Instability Instrument (AII) and static balance tests were used to assess functional ankle impairments related to CLAI. Isometric hip abduction and ankle eversion muscle strengths, and ankle dorsiflexion angle were also evaluated. Results One hundred twenty ankles from 60 male soccer players (mean age, 16.4 ± 0.7 years; mean duration of playing soccer, 9.8 ± 2.4 years) were included. ILAL was detected in 63.3% (38/60) of soccer players; 28 with ipsilateral ILAL (group I) and 10 with bilateral ILAL (group Bi). Seventeen participants (28.3%; 10 from group I, 3 from group Bi, and 4 from those without ILAL) showed a CAIT score of ≤24, and 5 (8.3%; 4 from group I and 1 from group Bi) showed an AII score of ≥5. The eversion muscle strength of the ankle with ILAL was significantly weaker than the contralateral side in group I ( p = 0.006). Conclusion ILAL was detected in approximately two‐thirds of adolescent male soccer players with relatively low CAIT and AII scores. In addition, the eversion muscle strength of the ankle with ILAL was significantly weaker than that of the contralateral side in subjects with ipsilateral ILAL. These findings suggest the possible importance of preventive interventions for soccer players with ILAL. Level of Evidence Level III.