Variation in ACL and MCL Strain Before Initial Contact Is Dependent on Injury Risk Level During Simulated Landings

Nathaniel A. Bates, Nathan D. Schilaty, Aaron J. Krych, Timothy E. Hewett

Research output: Contribution to journalArticle

Abstract

Background: The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC. Purpose: To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC. Study Design: Descriptive laboratory study. Methods: A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors. Results: Strain responses during simulated landing tasks for the ACL (P ≥.545) and MCL (P ≥.489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL (P <.001) and MCL (P <.001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC. Conclusion: Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture. Clinical Relevance: Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.

Original languageEnglish (US)
JournalOrthopaedic Journal of Sports Medicine
Volume7
Issue number11
DOIs
StatePublished - Jan 1 2019

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Collateral Ligaments
Anterior Cruciate Ligament
Ligaments
Wounds and Injuries
Biomechanical Phenomena
Knee
Rupture
Rehabilitation
Joints

Keywords

  • ACL
  • initial contact
  • joint biomechanics
  • knee injury
  • landing
  • MCL
  • sports medicine

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

Cite this

Variation in ACL and MCL Strain Before Initial Contact Is Dependent on Injury Risk Level During Simulated Landings. / Bates, Nathaniel A.; Schilaty, Nathan D.; Krych, Aaron J.; Hewett, Timothy E.

In: Orthopaedic Journal of Sports Medicine, Vol. 7, No. 11, 01.01.2019.

Research output: Contribution to journalArticle

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abstract = "Background: The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC. Purpose: To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC. Study Design: Descriptive laboratory study. Methods: A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors. Results: Strain responses during simulated landing tasks for the ACL (P ≥.545) and MCL (P ≥.489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL (P <.001) and MCL (P <.001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0{\%} in the ACL and 1.0{\%} in the MCL. Mean change in strain from the ACL ranged from 0.1{\%} to 3.9{\%} pre-IC and from 2.9{\%} to 5.7{\%} post-IC, while the MCL ranged from 0.0{\%} to 3.0{\%} pre-IC and from 0.9{\%} to 1.3{\%} post-IC. Conclusion: Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture. Clinical Relevance: Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.",
keywords = "ACL, initial contact, joint biomechanics, knee injury, landing, MCL, sports medicine",
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AU - Bates, Nathaniel A.

AU - Schilaty, Nathan D.

AU - Krych, Aaron J.

AU - Hewett, Timothy E.

PY - 2019/1/1

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N2 - Background: The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC. Purpose: To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC. Study Design: Descriptive laboratory study. Methods: A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors. Results: Strain responses during simulated landing tasks for the ACL (P ≥.545) and MCL (P ≥.489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL (P <.001) and MCL (P <.001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC. Conclusion: Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture. Clinical Relevance: Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.

AB - Background: The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC. Purpose: To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC. Study Design: Descriptive laboratory study. Methods: A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors. Results: Strain responses during simulated landing tasks for the ACL (P ≥.545) and MCL (P ≥.489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL (P <.001) and MCL (P <.001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC. Conclusion: Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture. Clinical Relevance: Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.

KW - ACL

KW - initial contact

KW - joint biomechanics

KW - knee injury

KW - landing

KW - MCL

KW - sports medicine

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