Biomechanical effects of the tibial slope angle change on total knee prosthesis: 3D finite elements analysis

Abstract

: In total knee arthroplasty, finding the correct tibial slope angle while placing the prosthesis affects the joint load. In our study; the load on the tibial insert and the notch of the insert as a result of flexion of the knee joint 0-30-60-90 degrees at each inclination in prostheses applied with posterior inclination angles of 0,3,5 and 7 degrees was examined in the three-dimensional right knee finite element structural model. In this way, it was aimed to reveal at which slope the resulting load is the lowest. The finite element structural model was created using the 3D 2.5 number right knee solid model. Two types of analysis were performed to examine the effect of angle change of the PE Insert on tibia component; static structural analysis with static loads at certain fixed flexion angles, and transient analysis with time for varying loadings at dynamically changing flexion angles with rotation of the knee between 0-90 degrees. In the 0 and 30 degree models, the least load on the tibial insert was found at 7 degree tibial slop angle (11.6 and 9.87 mpa, respectively), in 60 and 90 degree models at 5 degree tibial slop angle (9.07 and 11.4 mpa respectively). In the models of 0 and 30 degrees, no pressure occured on the tibial insert notch at 3,5,7 degrees of tibial slop angles, while in the 60 degree model, a pressure of 0,153 MPa occured at all 0,3,5,7 degrees at 0 degrees tibial insert slop angle and this pressure was centered at the junction with the tibial insert. The higher the load on the tibial insert, the greater wear of the tibial insert in the knee prosthesis. For this reason, it is important with which slop angle the tibial insert should be placed during surgery.