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128 Different strokes for different risk factors – task specificity in the context of ACL injury risk
  1. Haraldur Sigurðsson,
  2. Kristin Briem
  1. University Of Iceland, Hringbraut 31, Iceland


Introduction The dynamic knee valgus and the stiff landing are movement patterns associated with the anterior cruciate ligament (ACL) injury mechanism. Drop jumps (DJ) and cutting maneuvers (CM) are used to assess the risk of ACL injuries, but it is not known if such standardized athletic tasks are suitable to represent and assess these movement patterns. The aim of this study was to compare the DJ and CM impact-phase (within 70 ms) knee abduction moment (KAM) and the initial contact knee flexion angle (KFA).

Materials and Methods 100 athletes performed 10 repetitions of each movement before adolescence (aged 9–12) and again during adolescence, 5 years later. Kinematic and kinetic data were obtained using marker-based motion capture with force plates. Mixed models were used to assess the difference in the KAM and KFA during DJ and CM and adjusted for sex, leg, and age.

Results The DJ was associated with a lower KAM compared to the CM (0.23 Nm/kg vs 0.31 Nm/kg , p < 0.001). The DJ was associated with a lower KFA compared to the CM (28° vs 40°, p < 0.001).

Conclusion The CM is superior to demonstrate movement patterns that produce a higher KAM, but the drop-jump is superior to demonstrate propensity to land with a smaller KFA. Each task demonstrates separate movement patterns and should not be used inter-changeably. Researchers should diversify movement tasks and design them to induce kinematics and kinetics reflecting a specific movement pattern.

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