Functional anatomy of the anterior cruciate ligament. Fibre bundle actions related to ligament replacements and injuries

Abstract

This work studied the fibre bundle anatomy of the anterior cruciate ligament. Three functional bundles--anteromedial, intermediate, and posterolateral--were identified in cadaver knees. Their contributions to resisting anterior subluxation in flexion and extension were found by repeated tests after sequential bundle transection. Changes of length in flexion and extension and in tibial rotation were measured. None of the fibres were isometric. The posterolateral bundle was stretched in extension and the anteromedial in flexion, which correlated with increased contributions to knee stability and the likelihood of partial ruptures in these positions. Tibial rotation had no significant effect. The fibre length changes suggested that the 'isometric point' aimed at by some ligament replacements lay anterior and superior to the femoral origin of the intermediate fibre bundle and towards the roof of the intercondylar notch.

Effect of Femoral Tunnel Placement for Reconstruction of the Anterior Cruciate Ligament on Tibial Rotation

“…However, the anterior cruciate ligament does not function as a simple band of fibers with constant tension as the knee moves. Its two bundles exhibit different tension patterns and are susceptible to different forces 30 . When the knee is extended, the posterolateral bundle is tight and the anteromedial bundle is moderately lax.…”

The attachments of the anteromedial and posterolateral fibre bundles of the anterior cruciate ligament

“…1) by flexing and extending the knee to display their different tightening/slackening behaviour. In particular, the PL bundle becomes tight in knee flexion angles between 0° and 30°, whilst the AM bundle remains tight throughout flexion when an anterior displacement force is applied [2,5,19], allowing clear differentiation to be made between the two bundles. This is similar to that reported by Sakane et al [18] who used strain gauges to differentiate between the two bundles whilst passively flexing the knee.…”

Total knees designed for normal kinematics evaluated in an up‐and‐down crouching machine

“…This behavior is consistent with ACL anatomy, especially the antero-medial band, 32 which tightens in flexion. 33 Reuben et al 34 showed instability in AP tibial translations after ACL resection, up to about 608 flexion. In vivo studies showed abnormalities in rotation and translations in various activities after ACL injury, 35 although hamstrings function could alleviate this in stair ascent.…”