Lower Extremity Reaction Time in Individuals With Contact Versus Noncontact Anterior Cruciate Ligament Injuries After Reconstruction

Abstract

Context: Deficits in perceptual-motor function, like visuomotor reaction time (VMRT), are risk factors for primary and secondary anterior cruciate ligament (ACL) injury. Noncontact ACL injuries have been associated with slower reaction time, but whether this association exists for patients with contact ACL injuries is unknown. Exploring differences in VMRT among individuals with contact versus noncontact ACL injuries may provide a more comprehensive understanding of modifiable risk factors.

Objective: To compare lower extremity VMRT (LEVMRT) in individuals with contact or noncontact ACL injuries after ACL reconstruction (ACLR).

Design: Cross-sectional study.

Setting: Research laboratory.

Patients or other participants: A total of 36 participants with primary, unilateral ACLR completed an LEVMRT assessment (contact ACL injury = 20 [56%], noncontact ACL injury = 16 [44%]).

Main outcome measure(s): The LEVMRT was assessed bilaterally and collected using a series of wireless light discs deactivated by individuals with their feet. The ACLR-active LEVMRT (ie, ACLR limb is deactivating lights) and ACLR-stable LEVMRT were compared using separate analyses of covariance to determine the association with contact or noncontact injury using time since surgery as a covariate.

Results: After controlling for time since surgery, a difference and large effect size between groups was found for the ACLR-stable LEVMRT (P = .010; η2 = 0.250) but not for the ACLR-active (P = .340; η2 = 0.065) condition. The contact group exhibited slower ACLR-stable LEVMRT (521.7 ± 59.3 milliseconds) than the noncontact group (483.4 ± 83.9 milliseconds).

Conclusions: Individuals with contact ACL injury demonstrated a slower LEVMRT while their ACLR limb was stabilizing. The group differences during the ACLR-stable LEVMRT task might indicate deficits in perceptual-motor function when the surgical limb maintains postural control during a reaction time task. After ACLR, individuals with contact injuries may need additional motor learning interventions to enhance perceptual-motor functioning.

Keywords: knee injury; neurocognitive function.