Lumbar total disc replacement: a numerical study.

AIM The aim of this study was to evaluate the biomechanical effects of the Maverick(R) disc prosthesis at the implanted and adjacent level by the finite element (FE) method. MATERIALS AND METHODS A 3D FE model of the L3-L5 segment was built. To simulate the different physiological movements (flexion, extension, lateral bending, axial rotation) pure moments of 10 Nm were applied. To evaluate the effect of the prosthesis, a 3D model of the device was built and inserted in the L3-L5 model. The ROMs obtained with the intact model were imposed as maximal rotations to the instrumented model, therefore implementing the Panjabi hybrid protocol. RESULTS Increased ROMs at the implanted level and reduced ROMs at the adjacent level were predicted. A similar moment-rotation behavior was calculated after simulation of prosthesis insertion. No significant effect was predicted in terms of von Mises stress at the adjacent level after implantation of the prosthesis. CONCLUSIONS Within the limitations of the models, the numerical results of this study predicted a preserved kinematics and stress at the adjacent segment, after insertion of the prosthesis.