KNEE FLEXION AND DIFFERENTIAL FIBRE RECRUITMENT IN THE ANTERIOR CRUCIATE LIGAMENT: A MICROSTRUCTURAL STUDY

SummaryThe presence or absence of crimp within the anterior cruciate ligament (ACL) sub-bundle anatomy was correlated with knee flexion angle changes and provided a measure of differential loading within its sub-bundle microstructure.IntroductionPrevious studies have shown that macroscopically the anteromedial (AM) and posterolateral (PL) bundles of the ACL tighten/slacken differently with knee flexion angle. This research used fibre crimp morphology, revealed following in situ fixation of the intact ligament structures, to investigate patterns of differential fibre recruitment across each ACL sub-bundle.MethodsTwelve mature ovine knees were divided into four test-groups of three: control, hyper-extension (8°), neutral position (50°), and deep flexion (170°). For the control group, ligament-bone (tibia) samples were isolated and chemically fixed, unconstrained, in 10% formalin. For the flexed groups the whole joints were first positioned in the relevant angle of flexion using a custom-built rig and formal...