Reliability of dynamic balance simultaneously with cognitive performance in patients with ACL deficiency and after ACL reconstructions and in healthy controls.

PURPOSE: To determine the intra- and inter-session reliability of balance and cognitive performance in anterior cruciate ligament-deficient (ACLD) and ACL-reconstructed (ACLR) and matched athletes.

METHODS: Using SMART EquiTest, recovery reactions of the groups were assessed during single-leg standing, following medium and large forward perturbations with and without performing a cognitive (Stroop) task. The outcomes included reaction time (RT), latency and amplitude for balance and error ratio (ER) and RT for cognitive performance. The participants of each group repeated the tests 2-7 days after the first session. Intraclass correlation coefficient (ICC) and standard error of measurement were computed in order to assess relative and absolute reliability, respectively.

RESULTS: Single- and dual-task balance measures had moderate to very high reliability in ACLD (ICC = 0.63-0.88), ACLR (ICC = 0.62-0.93) and control (ICC = 0.69-0.98) athletes. The ICCs for RT of Stroop were between 0.87 and 0.90 in ACLD, between 0.70 and 0.74 in ACLR and between 0.66 and 0.70 in controls and for ER of Stroop were between 0.36 and 0.90 in ACLD, between 0.42 and 0.49 in ACLR and between 0.41 and 0.51 in controls.

CONCLUSIONS: Balance measures and RT of the cognitive task in single- and dual-task conditions have acceptable reliability and may be incorporated into the evaluation of physical and mental function of athletes following ACL injury and reconstruction. ER of the cognitive task is less reliable which needs to be considered in future research.

LEVEL OF EVIDENCE: Prognostic study, case-control, Level III.