Deficits in perceptual-motor function, like visuomotor reaction time (VMRT), are risk factors for primary and secondary ACL injury. Non-contact ACL injuries have been associated with slower reaction time, but it is unknown if this association exists for patients with contact ACL injuries. Exploring differences in VMRT between non-contact and contact ACL injuries may provide a more comprehensive understanding of modifiable risk factors between mechanisms of injury.
To compare lower extremity VMRT (LEVMRT) between individuals with contact and non-contact ACL injuries after ACLR.
Thirty-six participants with primary, unilateral ACLR completed a LEVMRT assessment. Twenty participants sustained a contact ACL injury (56%), and 16 participants (44%) sustained a non-contact ACL injury.
LEVMRT was completed bilaterally and collected using a series of wireless light discs deactivated by the individual with their feet. ACLR-Active LEVMRT (i.e., ACLR limb is deactivating lights) and ACLR-Stable LEVMRT were compared using separate ANCOVA to assess the association between contact and non-contact groups with time since surgery (TSS) as a covariate.
After controlling for TSS, there was a statistically significant difference and large effect size between groups for ACLR-Stable LEVMRT (p = 0.010; η2 = 0.250), but not for ACLR-Active (p = 0.340; η2 = 0.065). The contact group exhibited slower ACLR-Stable LEVMRT (521.7 ± 59.3) compared to the non-contact group (483.4 ± 83.9).
Individuals with contact ACL injury demonstrated slower LEVMRT while their ACLR limb was stabilizing. The observed group differences during the ACLR-Stable LEVMRT task might indicate deficits in perceptual-motor function when the surgical limb maintains postural control during an RT task. Individuals after ACLR with contact injuries may need additional motor learning interventions to enhance perceptual-motor functioning after ACLR.