Biomechanics of a lumbar section after disc arthroplasty

Abstract

Total replacement of degenerated intervertebral disc (IVD) is preferable to vertebral bone fusion due to the possible restoration of near normal physiological function of the spinal column after surgery. The replacement usually involves implantation of metallic endplates with a bearing liner made of polymeric material sandwiched in between the endplates to allow easy motion of the replaced vertebral section. In this paper, the biomechanics of a lumbar vertebral section was analysed before and after total disc replacement. Finite element model of an L3-L4 segment was developed from computed tomography image datasets. Disc implant was modelled and placed in between the vertebral segment to simulate disc arthroplasty. Another model with an intact IVD was also analysed for comparison. Loads simulating the physiological flexion, extension and lateral bendings were applied to the superior surface of L3. Nonlinear contact analysis was used in the analysis of the replaced IVD. Results showed that the replaced IVD managed to restore the relevant functionalities with regard to the range of motion of the vertebral section.