Visual-Motor Control of Drop Landing After Anterior Cruciate Ligament Reconstruction

Context: Visual feedback is crucial in the control of human movement. When vision is obstructed, alterations in landing neuromuscular control may increase movements that place individuals at risk for injury. Anterior cruciate ligament (ACL) injury may further alter the motor-control response to alterations in visual feedback. The development of stroboscopic glasses that disrupt visual feedback without fully obscuring it has enabled researchers to assess visual-motor control during movements that simulate the dynamic demands of athletic activity. Objective: To investigate the effect of stroboscopic visual-feedback disruption (SVFD) on drop vertical-jump landing mechanics and to determine whether injury history influenced the effect. Design: Cohort study. Setting: Movement-analysis laboratory. Patients or Other Participants: A total of 15 participants with ACL reconstruction (ACLR; 7 men, 8 women; age = 21.41 +/- 2.60 years, height = 1.72 +/- 0.09 m, mass = 69.24 +/- 15.24 kg, Tegner Activity Scale score = 7.30 +/- 1.30, time since surgery = 36.18 +/- 26.50 months, hamstrings grafts = 13, patellar tendon grafts = 2) and 15 matched healthy control participants (7 men, 8 women; age =23.15 +/- 3.48 years, height = 1.73 +/- 0.09 m, mass = 69.98 +/- 14.83 kg, Tegner Activity Scale score = 6.77 +/- 1.48). Intervention(s): Drop vertical-jump landings under normal and SVFD conditions. Main Outcome Measure(s): The SVFD effect for knee sagittal- and frontal-plane excursions, peak moments, and vertical ground reaction force were calculated during landing and compared with previously established measurement error and between groups. Results: The SVFD altered knee sagittal-plane excursion (4.04 degrees +/- 2.20 degrees, P= .048) and frontal-plane excursion (1.98 degrees -+/- 1.53 degrees, P= .001) during landing above within-session measurement error. Joint-moment difference scores from full vision to the SVFD condition were not greater than within-session error. We observed an effect of ACLR history only for knee flexion (ACLR group = 3.12 degrees +/- 3.76 degrees, control group = -0.84 degrees +/- 4.45 degrees; P= .001). We did not observe an effect of side or sex. Conclusions: The SVFD altered sagittal- and frontal-plane landing knee kinematics but did not alter moments. Anterior cruciate ligament reconstruction may induce alterations in sagittal-plane visual-motor control of the knee. The group SVFD effect was on a level similar to that of an in-flight perturbation, motor-learning intervention, or plyometric-training program, indicating that visual-motor ability may contribute to knee neuromuscular control on a clinically important level. The individual effects of the SVFD indicated possible unique sensorimotor versus visual-motor movement strategies during landing.