This study was carried out to clarify the biomechanical characteristics of the lumbar intervertebral disc using a three-dimensional finite element method.
The geometry of the finite element model is based on the movement of the L4-5 segment without a posterior element in a 29-year-old man, obtained from 2mm thick computed tomography scans. The finite element model included material properties of the cortical bone, cancellous bone, end plate, nucleus pulposus and annulus fibrosus. Simulated loads were applied at the top of the upper vertebral body, while the lower vertebra was fixed.
Strain distribution results indicate that the highest tensile strain occured in the innermost annulus fibrosus at the posterolateral location during flexion. It is suggested that increase in the strain at the posterolateral location of the annulus fibrosus in flexion with other loads is an important factor in the mechanism leading to disc prolapse.
