Unanticipated Run-to-Cut Task Increased Knee Injury Risk Mechanics in Athletes with Prior Concussion

Purpose To compare knee kinematics between athletes recently returned to play after a concussion and matched controls during an unanticipated run-to-cut maneuver to identify injury-related movement patterns. Method Seven post-concussion athletes (within 48hrs post return to play) were matched by age, sport, and sex to uninjured athletes (age=21.71±2.29, female=76/108;70.4%). Athletes ran 4.5±0.45 mph along a 12-ft runway and executed a contralateral 45° cut to the right or left in response to a directional Flanker stimulus presented 915 ms after gait initiation. Planting knee angles were measured at initial contact and at the time of peak ground reaction force (GRF) and compared using independent t-tests. Results For the left leg, there were no significant differences in knee angles (flexion, valgus, external rotation) at initial contact or at peak GRF between athletes with and without a history of concussion (all p>0.132). For the right leg, athletes in the concussion group demonstrated greater external rotation (3.38±9.99° vs -7.59±8.56°; p=0.024) at initial contact and greater external rotation (7.72±7.44° vs 0.36±7.64°; p=0.046) and greater valgus angle (4.9±3.14° vs 0.35±3.04°; p=0.009) at peak GRF when compared to healthy controls. All other knee angles were not significantly different (p>0.05). Conclusions Athletes with a history of concussion exhibit altered knee movement strategies during unanticipated cutting tasks. While these strategies may allow task completion, they may reflect compensatory motor patterns that reduce the capacity to safely absorb and redirect forces during rapid direction changes, potentially increasing the risk of musculoskeletal injury during unanticipated movements.