Prediction of biomechanical behavior of lumbar vertebrae using a novel semi-rigid stabilization device

The work investigates the effect of proposed novel semi-rigid stabilization device on lumbar segment L2-L3 so as to preserve motion at vertebral level. Here, the biomechanical behavior of intact spine with three instrumented spinal models (semi-rigid stabilization device, rigid implant and dynamic stabilization system NFlex) have been compared under the motion conditions of flexion, extension, bending and twist. Three-dimensional non-linear finite models of intact spine, semi-rigid stabilization device, rigid implant and dynamic stabilization system NFlex were developed in the present study. All the four models were subjected to a combined load of 400 N in axial compression along with 2, 4, 6, 8 and 10 N m as bending moment individually. Dynamic stabilization system NFlex shows the maximum variation in motion and reflects range of motion as 89.7% during lateral bending, 53.4% in flexion, 34.6% in twist and 28.0% in extension with respect to intact spine. However, semi-rigid stabilization device and rigid implant shows the range of motion of 60%, 48.7%, 32% and 21.8% and 60%, 32.3%, 22.3% and 21.7% of intact, respectively, during bending, flexion, twist and extension. Finite element simulation results reveal that semi-rigid stabilization device shows comparatively lower values than dynamic stabilization system NFlex and higher as compared to rigid implant for measured intradiscal pressure and von Mises strain at intervertebral disc-23.