Sport-Dependent Variations in Arm Position During Single-Limb Landing Influence Knee Loading

Background: Increased valgus loading at the knee has been previously identified as a possible risk factor for noncontact anterior cruciate ligament injuries, which are common in sports. Arm position variation may affect risk of injury by altering valgus knee loading. Hypothesis: Sport-dependent variations in arm position increase valgus loading of the knee during run-to-cut maneuvers. Study Design: Controlled laboratory study. Methods: Eleven subjects performed a sidestep cutting maneuver, first with no arm constraints and then with 3 sports-related arm positions in random order (holding a lacrosse stick, holding a football on the plant side, and holding a football on the cut side). The analysis focused on the knee valgus moment relative to the arm positions during the landing phase of the activity. Results: Arm position significantly influenced the valgus moment with an increase in the lacrosse trials and in the plant-side football trials but not in the cut-side football trials (α = .05). Conclusions: Constraining the plant-side arm results in increased valgus loading at the knee during run-to-cut maneuvers, which suggests the possibility of greater risk of anterior cruciate ligament injury during these conditions. Clinical Relevance: These results suggest that training methods that consider arm position as a risk factor could help reduce the risk of anterior cruciate ligament noncontact injury. Keywords: anterior cruciate ligament (ACL) injury injury mechanisms football lacrosse knee biomechanics noncontact injury