Stress changes of lateral collateral ligament at different knee flexion with or without displaced movements: a 3-dimensional finite element analysis.

ABSTRACT

OBJECTIVE: To create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament (LCL) with or without displaced movements at different knee flexion conditions. METHODS: A four-major-ligament contained knee specimen from an adult died of skull injury was prepared for CT scanning with the detectable ligament insertion footprints, locations and orientations precisely marked in advance. The CT scanning images were converted to a 3-dimensional model of the knee with the 3-dimensional reconstruction technique and transformed into finite element model by the software of ANSYS. The model was validated using experimental and numerical results obtained by other scientists. The natural stress changes of LCL at five different knee flexion angles (0 degree, 30 degree, 60 degree, 90 degree, 120 degree) and under various motions of anterior-posterior tibial translation, tibial varus rotation and internal-external tibial rotation were measured. RESULTS: The maximum stress reached to 87%-113% versus natural stress in varus motion at early 30 degree of knee flexions. The stress values were smaller than the peak value of natural stress at 0 degree (knee full extension) when knee bending was over 60 degree of flexion in anterior-posterior tibial translation and internal-external rotation. CONCLUSION: LCL is vulnerable to varus motion in almost all knee bending positions and susceptible to anterior-posterior tibial translation or internal-external rotation at early 30 degree of knee flexions.