The Effect of Mechanical Varus on Anterior Cruciate Ligament and Lateral Collateral Ligament Stress: Finite Element Analyses.
The current study analyzed changes in anterior cruciate ligament (ACL) and lateral collateral ligament stress as a result of mechanical varus. In an exploratory pilot study, progressive mechanical varus was introduced to a male finite element model of the lower limb at different knee flexion angles. Nine situations were analyzed (combinations of 0°, 30°, and 60° knee flexion and 0°, 5°, and 10° varus). The ACL stress was measured via changes in section force, von Mises stress, and fiber stress. Lateral collateral ligament stress was measured via changes in section force. For all 3 measures of the ACL, maximum stress values were found in extension, stress decreased with flexion, and the effect of varus introduction was most significant at 30° flexion. With 60° flexion, varus introduction produced a decrease in section force and von Mises stress and a small increase in fiber stress. In all situations and stress measures except fiber stress at 60° flexion, stress was concentrated at the posterolateral bundle. For the lateral collateral ligament, the introduction of 5° and 10° varus caused an increase in section force at all degrees of flexion. Stress in the ligament decreased with flexion. Mechanical varus of less than 10° was responsible for increased ACL stress, particularly at 0° and 30° knee flexion, and for increased lateral collateral ligament stress at all degrees of flexion. Stress was mostly concentrated on the posterolateral bundle of the ACL. [Orthopedics. 2016; 39(4):e729-e736.].
Betina B
BB
Hinckel
Marco K
MK
Demange
Riccardo G
RG
Gobbi
José Ricardo
JR
Pécora
Gilberto Luis
GL
Camanho
D016118:Anterior Cruciate Ligament / Q000502:physiology*; D017885:Collateral Ligaments / Q000502:physiology*; D020342:Finite Element Analysis; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008953:Models, Anatomic; D010865:Pilot Projects; D016059:Range of Motion, Articular; D013314:Stress, Mechanical