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In vivo kinematics of the ACL during weight‐bearing knee flexion
Author(s) -
Li Guoan,
DeFrate Louis E.,
Rubash Harry E.,
Gill Thomas J.
Publication year - 2005
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1016/j.orthres.2004.08.006
Subject(s) - anterior cruciate ligament , kinematics , biomechanics , knee flexion , weight bearing , anatomy , orientation (vector space) , elongation , ligament , twist , orthodontics , rotation (mathematics) , materials science , medicine , mathematics , physics , geometry , surgery , composite material , ultimate tensile strength , classical mechanics
No study has investigated the three‐dimensional morphological changes of the anterior cruciate ligament (ACL) during functional activities in vivo. The purpose of this study was to analyze the elongation, rotation (twist), and orientation of the ACL during weight‐bearing flexion in five human subjects using dual‐orthogonal fluoroscopic images and MR image‐based computer models. The ACL consistently decreased in length with flexion. At 90°, the length decreased by 10% compared to its length at full extension. The ACL twisted internally by only 20° at 30° of flexion. The ACL was oriented more vertically (approximately 60°) and slightly laterally (approximately 10°) at low flexion angles. These data on in vivo ligament elongation demonstrate that the ACL plays a more important role in lower flexion angles than at higher flexion angles during weight‐bearing flexion. These data also suggest that successful ACL reconstruction should not only restore the ligament's elongation behavior, but also its rotational and orientation characteristics, so that normal ACL biomechanics are restored. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.