Neurocognitive Challenges During Drop Vertical Jumps Increase Sensitivity to Differentiate Atypical Landing Mechanics and Jump Height in Individuals With Anterior Cruciate Ligament Reconstruction

Abstract

Background: Athletes with anterior cruciate ligament reconstruction (ACLR) have high rates of secondary injury. Insufficient return-to-sport screening may be due to standard functional tests not resembling chaotic sporting environments where injuries occur. Neurocognitive deficits among individuals with ACLR indicate that cognitive challenges during screening tests may better reveal atypical movement mechanics. Hypothesis: Adding secondary cognitive tasks to drop vertical jumps (DVJs) would increase between-group differences in landing mechanics and jump height compared with the standard DVJ. Study Design: Controlled laboratory study. Methods: Forty sports-active individuals 24.9 ± 16.1 months after unilateral ACLR and 40 uninjured controls (both groups 50% female) performed DVJs; downward- or upward-pointing arrows indicated whether to drop only or complete the vertical jump. Conditions were (1) black arrow presented before drop and (2) black or red arrow presented during drop (red arrow pointing in opposite direction of requested motor action) together with a memory task involving letter recalling. Jump height and biomechanical time-series data from an 8-camera motion capture system and 2 force plates during the first 100 ms of landing were compared between groups using conventional and functional t tests, respectively. Results: For the standard DVJ, the ACLR group had significantly less hip power and more hip abduction moment for the injured leg and uninjured leg, respectively, compared with controls. For the DVJ with secondary cognitive tasks, the ACLR group again showed significantly less hip power and more hip abduction moment but also less knee power, knee flexion moment, ankle power, and ankle dorsiflexion moment and lower jump height than controls. Conclusion: The addition of secondary cognitive tasks during DVJs elicited further significant differences in landing mechanics and jump performance among athletes with ACLR compared with uninjured athletes than were found for the standard DVJ. The aberrant biomechanical outcomes for the ACLR group indicate an incomplete rehabilitation. Clinical Relevance: The greater between-group differences in landing mechanics and jump height when adding secondary cognitive tasks to a DVJ indicate a need to provide neurocognitive challenges in rehabilitation and return-to-sport screening as a first step toward improved rehabilitation outcomes and more ecologically valid testing.