Background Prevalence of lateral ankle sprains (LAS) is high among adolescent athletes resulting in time loss from sport and, often, long term functional ankle instability (FAI): a major risk factor for re-injury.

Objective This study aimed to assess the sensitivity of the Balance Error Scoring System (BESS) to detect FAI in adolescent athletes.

Design Case control study.

Setting Youth sport in an UK independent school

Participants Twenty-seven athletes who had sustained a past ankle injury took part. Selection criteria included participant involvement in the school athletic development programme.

Assessment of Risk Factors A modified BESS protocol was used. Participants balanced on one leg for 20 seconds on a stable surface (the ground) followed by an unstable surface (Airex balance pad), keeping their eyes closed and hands on hips. Both ankles were tested across each surface.

Main Outcome Measurements Participants received an error score for each condition (capped at 10 errors). Errors included: opening eyes, moving hands off hips, lifting toes or heel up, abduction or flexion at the hip >30° and stepping, stumbling, or falling.

Results There was no significant difference in error score between the ankle that had previously been injured and that which had not on a stable (p=1.0) and unstable (p=0.46) surface. On the unstable surface, the error score (mean ± standard deviation) was 7.5±1.8 for athletes with a previous ankle injury and 7.8±1.4 for athletes without a previous ankle injury. On the stable surface, the error score (mean ± standard deviation) was 3.2±2.3 for athletes with a previous ankle injury and 3.2±2.3 for athletes without a previous ankle injury.

Conclusions The BESS was not able to detect previous ankle injury or FAI in adolescent athletes. Using the BESS in conjunction with other assessment tools may allow practitioners to screen for more ankle injury risk factors.