A finite element model of full endoscope lumbar fenestration and biomechanical characteristics / 中国组织工程研究

ABSTRACT

BACKGROUND: The effective treatment of lumbar spinal stenosis with total endoscopic decompression is a breakthrough frontier technology. Compared with open surgery, it has the characteristics of fewer traumas, controllable operation, and fewer complications, but it reported less in finite element biomechanics. OBJECTIVE: To establish a finite element model of full endoscope lumbar fenestration and to investigate the effects of decompression range and nucleus pulposus removal on lumbar range of motion and stress distribution of disc. METHODS: CT scan data of a case of L4-5 segmental lumbar spinal stenosis were collected and imported in Mimics 20.0 software. A finite element model M of L4-5 lumbar spinal stenosis in degenerative lumbar spine was established. The model M was imported into 3-matic for surgical simulation, i.e., unilateral disc resection of the small joints 1/2 and 1/4 model M1, bilateral joints 1/2 and 1/2 resection of intervertebral disc model M2, and unilateral disc and articular process of 1/4 model M3. In the ANSYS software, the mechanical comparative analysis was conducted in four kinds of models under six working conditions of the same pure couple moment, including forward bending, backward extension, left bending, right bending, left rotation and right rotation, and the same load of the intervertebral disc. RESULTS AND CONCLUSION: (1) Compared with the spinal M model, the range of motion of M1 model was similar under six working conditions, but the range of motion of M2 and M3 was significantly increased than that of M, especially under the left/right flexion and forward/backward flexion working conditions, which was 130%-200% of the overall activity of M model. (2) In terms of the stress of intervertebral disc, M1 model showed no obvious upward trend of the effect force in the posterior region, central region and right region of intervertebral disc under various working conditions. The equivalent stress in the left region and front region of intervertebral disc increased to a maximum of 63%, but there was no significant stress concentration. In the M2 and M3 models, the equivalent stress of intervertebral discs in all regions showed a significant increased trend. (3) Endoscopic minimally invasive surgery is accurate and controllable for different types of lumbar spinal stenosis decompression surgery. The resection of facet joints and the removal of nucleus pulposus by less than 1/2 have little influence on the biomechanical stability of the corresponding segments. The successful and reliable finite element modeling of lumbar lamina fenestration can provide an important method and basis for the follow-up biomechanical study of lumbar surgery.