Single-limb drop landing biomechanics in active individuals with and without a history of anterior cruciate ligament reconstruction: A total support analysis

Background: The purpose of this study was to characterize the magnitude and distribution of the total support moment during single-limb drop landings in individuals after anterior cruciate ligament reconstruction compared to a control group. Methods: Twenty participants after reconstruction and twenty control participants matched on sex, limb dominance and activity level were recruited. Motion analysis was performed during a single-limb drop landing task. Total support moment was determined by summing the internal extensor moments at the ankle, knee, and hip. Each relative joint contribution to the total support moment was calculated by dividing each individual contribution by the total support moment. Data were captured during a landing interval that started at initial contact and ended at the lowest vertical position of the pelvis. Data were then time-normalized and indexed at 25, 50, 75, and 100% of the landing interval. Findings: No between-group differences for total support moment magnitude were observed. At both 75% and 100% of the landing, the relative contribution of the knee joint was lower in those with a history of surgery (p < 0.001). At the same instances, the relative contribution to the total support moment by the hip joint was greater in those with a history of surgery (p = 0.004). Interpretation: In active participants after anterior cruciate ligament reconstruction, relative contributions to anti-gravity support of the center of mass shifted from the knee to the hip joint during single-limb landing, which became evident towards the end of the landing interval. (C) 2017 Elsevier Ltd. All rights reserved.