Biomechanical evaluation of human lumbar spine in spondylolisthesis

One of the least known conditions of the lumbar spine in terms of biomechanics is spondylolisthesis which causes many serious consequences for the patient. This research aimed to perform a mechanical analysis of the origins of spondylolisthesis and its impact on the biomechanics of the lumbar section of the spine. Within the framework of this study, a physiologically model of the lumbar spine was created in the MADYMO software. In the next stage a slip of vertebra L4 was simulated by means of a controlled forward displacement of the vertebral body of vertebra L4. 10 variants of spondylolisthesis (W1-W10) of different degrees were subjected to a biomechanical evaluation. In maximum bending of the physiological spine at an angle of 27° the value of the shear force amounted to 1.9 kN, while for the spine affected by spondylolisthesis with slip grade W9 at the maximum bending of 34° the shear force amounted to 5.5 kN. It was observed that the lumbar spine with the simulated spondylolisthesis had greater mobility in comparison with the physiological spine, which was shown by maximum bending angles (physiological 27°, W9 34°).