The Loading Mechanism after Partial Discectomy：Three-Dimensional Nonlinear Finite Element Analyses

• Main Authors: Ruei-Heng Lin, 林汭衡
• Other Authors: Weng-Pin Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/97310963847320133235

碩士 === 中原大學 === 醫學工程研究所 === 96 === The structure and composition of the annulus fibrosus (AF) were intricate with annulus ground substance and annulus fibers. The NP bulges radially and is constrained by the AF in compressive loading. The AF produced two kinds of different direction annulus stresses in axial plane: axial tension (AT), and axial compression (AC). Otherwise, the AF produced two kinds of different direction annulus stresses : circumferential tension (CT), and radial compression (RC). Herniated intervertebral disc (HIVD) is a common disease encountered in clinical practice. Partial discectomy may be indicated while conservative treatment being ineffective or severe compressing to neural structures. After discectomy, intervertebral disc damage and excision had been shown to alter lumbar spine mechanics according to the literatures. Since there is lacks of detail information about the stability or mechanical change in different surgical cutting methods or extension of partial discectomy. A three-dimensional nonlinear finite element model of L4-L5 was developed to analyze the mechanical change by range of motion (ROM) and neutral zone (NZ) under three patterns of loading conditions on the lumbar spinal motion segment. And the segments were loaded up to 400N follower pre-load. The same stress-strain tendency (Chuang et al. 2006) for AF was found for loading in four different directions. Circumferential stiffness moduli in both 25% and 50% strain were higher than in other principal. In the result of L4-5, there was no significant difference in incision types of discectomy except in annulotomy. The NZ and ROM were increased in annulotomy group. The ROM and NZ were increased by removing the nucleus pulposus.