Open AccessTiming, not magnitude, of force may explain sex‐dependent risk of ACL injury
Author(s) -
Sigurðsson Haraldur B.,
Sveinsson Þórarinn,
Briem Kristín
Publication year - 2018
Publication title -
knee surgery, sports traumatology, arthroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.806
H-Index - 125
eISSN - 1433-7347
pISSN - 0942-2056
DOI - 10.1007/s00167-018-4859-9
Subject(s) - valgus , ground reaction force , anterior cruciate ligament , acl injury , internal rotation , moment (physics) , medicine , rotation (mathematics) , physics , orthodontics , surgery , mathematics , geometry , kinematics , engineering , mechanical engineering , classical mechanics
Purpose The anterior cruciate ligament is loaded through valgus moment, vertical ground reaction force, and internal rotation moment. The aim of this study was to compare the timing of force peaks during early stance between youth girls and boys. Methods One‐hundred and twenty‐nine team sport athletes aged 9–12 completed a total of 2540 cutting maneuvers captured with an 8‐camera motion capture system. Timing of early force peaks was analyzed within 100 ms after ground contact. Results Genders showed different mean (95% CI) time to peak valgus—(32 ms (30–33 ms) vs 37 ms (36–38 ms), P < 0.001) and time to peak internal rotation moments (36 ms (35–37 ms) vs 38 ms (37–39 ms), P = 0.029) but not time to peak vertical ground reaction force [38 ms (37–40 ms) vs 37 ms (36–38 ms, n.s.)]. Girls showed a smaller time between vertical ground reaction force and valgus moment peaks (mean (95% CI) of 1 ms (1–2 ms) vs 7 ms (5–9 ms), P < 0.001), and valgus‐ and internal rotation moment peaks (0 ms (− 2 to 1.0 ms) vs − 5 ms (− 6 to − 3 ms), P = 0.0003) but not between internal rotation moment and vertical ground reaction force. Conclusions Concurrent force peaks are more common for girls compared with boys, leading to more frequent multi‐planar loading of the knee. Timing may explain sex‐dependent risk of ACL injuries. Exposure to repeated cutting movements may result in greater ACL injury risk due to timing of knee forces as well as magnitude. Such exposure should be minimized for at‐risk athletes. Level of evidence III.