The Effect Of Stroboscopic Eyewear On Single-limb Landing Kinetics In ACLR And Healthy Individuals.

Anterior cruciate ligament reconstruction (ACLR) aims to restore mechanical stability to the knee after injury. Despite surgical and rehabilitation efforts, lingering neuromuscular deficits may put ACLR individuals at an increased risk of re-injury when returning to sport. With reduced somatosensory input hypothesized, further perturbation to the visual system may elevate re-injury risk. PURPOSE: To evaluate single-limb landing kinetics in ACLR individuals under various levels of visual disruption. METHODS: Thirteen physically active ACLR individuals (M = 5 and F = 7, 20.0 ± 1.3 yr, 75.9 ± 8.4 kg, 1.7 ± 0.09 m, 29.3 months since surgery) and thirteen age (± 4 yrs) and sex-matched controls (M = 5 and F = 7, 21.3 ± 2.1 yr, 68.9 ± 11.9 kg, 1.7 ± 0.10 m) volunteered for the study. Before testing, participants completed self-reported questionnaires (Tegner Activity Scale and International Knee Documentation Committee (IKDC)), a 5-minute warm-up (1.3 m/s treadmill walk), and three maximal vertical jump height (VJH) assessments. Each participant completed a forward hopping task under three visual conditions, starting from a two-footed position (set at 40% of the individual’s body height to the center of the force plate), hopping to touch an overhead target (set at 50% of VJH), and landing in a single-limb position on a force plate (2000 Hz). The three levels of visual disruption were: 1) none (eyes open), low visual disruption (LVD), and 3) high visual disruption (HVD), achieved using stroboscopic eyewear cycling between clear (100 ms) and opaque (100 ms for LVD; 250 ms for HVD). The ACLR limb was compared to the dominant limb of the control group. Peak vertical ground reaction force (normalized to body weight) and loading rate were analyzed using multiple repeated measures ANOVAs to compare groups and visual conditions. RESULTS: ACLR individuals reported lower IKDC (85.8 ± 12.5) scores than controls (98.4 ± 3.0) (p<.01). No other significant interactions or main effects were found for the remaining dependent variables. CONCLUSIONS: Although ACLR individuals reported lower levels of knee function, no differences in peak BW or loading rate were found. Neuromuscular function may be restored in ACLR individuals roughly two years from surgery, even with the additional challenge of a visual constraint during a single-limb landing.