ABSTRACT
Objective To study the role of medial collateral ligament (MCL) in maintaining the stability of the knee joint by constructing the three-dimensional (3D) finite element model of the knee joint. Method sCT scans were performed after the MCL was marked by steel wires and the end point was marked by the dill hole. Then the 3D finite element model of the knee joint including ligaments was constructed with Mimics, Geomagic and Ansys software to simulate the anterior-posterior translation, valgus and internal-external rotation of the knee joint at different flexion angles. Results With the knee at 0, 30, 60, 90 and 120 degree of flexion，the initial stresses of MCL were 4.84, 3.55, 2.17, 1.26 and 0 MPa, respectively. When the knee joint was subjected to anterior translation loading, the stresses were 7.22, 5.78, 4.07, 2.84 and 1.4 MPa, respectively. When the knee joint was subjected to posterior translation loading, the stresses were 8.14, 6.45, 4.19, 2.92 and 1.6 MPa, respectively. When the knee joint was subjected to internal rotation loading, the stresses were 6.81, 5.23, 3.29, 2.25 and 0.97 MPa, respectively. When the knee joint was subjected to external rotation loading, the stresses were 6.28, 5.00, 3.34, 2.21 and 0.82 MPa, respectively. When the knee joint was subjected to valgus loading, the stresses were 11.00, 9.55, 7.25, 5.94 and 3.11MPa, respectively. Conclusions The biomechanical function of MCL can be effectively analyzed by establishing the 3D finite element model of the knee joint to simulate the anterior-posterior translation, valgus and internal-external rotation of the knee joint.
ABSTRACT
<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>