Different roles of the medial and lateral hamstrings in unloading the anterior cruciate ligament

David R. Guelich, Dali Xu, Jason L. Koh, Gordon W. Nuber, Li Qun Zhang*

*Corresponding author for this work

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Introduction: Anterior cruciate ligament injuries are closely associated with excessive loading and motion about the off axes of the knee, i.e. tibial rotation and knee varus/valgus. However, it is not clear about the 3-mechanical actions of the lateral and medial hamstring muscles and their differences in loading the ACL. The purpose of this study was to investigate the change in anterior cruciate ligament strain induced by loading the lateral and medial hamstrings individually. Methods: Seven cadaveric knees were investigated using a custom testing apparatus allowing for six degree-of-freedom tibiofemoral motion induced by individual muscle loading. With major muscles crossing the knee loaded moderately, the medial and lateral hamstrings were loaded independently to 200 N along their lines of actions at 0°, 30°, 60° and 90° of knee flexion. The induced strain of the anterior cruciate ligament was measured using a differential variable reluctance transducer. Tibiofemoral kinematics was monitored using a six degrees-of-freedom knee goniometer. Results: Loading the lateral hamstrings induced significantly more anterior cruciate ligament strain reduction (mean 0.764 [SD 0.63] %) than loading the medial hamstrings (mean 0.007 [0.2] %), (= 0.001 and effect size = 0.837) across the knee flexion angles. Conclusion: The lateral and medial hamstrings have significantly different effects on anterior cruciate ligament loadings. More effective rehabilitation and training strategies may be developed to strengthen the lateral and medial hamstrings selectively and differentially to reduce anterior cruciate ligament injury and improve post-injury rehabilitation. Clinical Relevance: The lateral and medial hamstrings can potentially be strengthened selectively and differentially as a more focused rehabilitation approach to reduce ACL injury and improve post-injury rehabilitation. Different ACL reconstruction procedures with some of them involving the medial hamstrings can be compared to each other for their effect on ACL loading.

Original languageEnglish (US)
Pages (from-to)97-101
Number of pages5
JournalKnee
Volume23
Issue number1
DOIs
StatePublished - Jan 1 2016

Keywords

  • ACL
  • Lateral hamstring
  • Medial hamstring

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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