Ho-Joong Kim1, Heoung-Jae Chun2, Kyoung-Tak Kang2, Hwan-Mo Lee3, Bong-Soon Chang4, Choon-Ki Lee4, Jin-S Yeom5. 1. Spine Center and Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. 2. Department of Mechanical Engineering, Yonsei University, Seoul, Korea. 3. Department of Orthopedic Surgery, Yonsei University College of Medicine, Seoul, Korea. 4. Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea. 5. Spine Center and Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. highcervical@gmail.com.
Abstract
PURPOSE: The purpose of this study was to evaluate and compare the biomechanical behavior of the lumbar spine after posterior decompression with the spinous process osteotomy (SPiO) technique or the conventional laminectomy (CL) technique using a finite element (FE) model. MATERIALS AND METHODS: Three validated lumbar FE models (L2-5) which represented intact spine and two decompression models using SPiO and CL techniques at the L3-4 segment were developed. In each model, the ranges of motion, the maximal von Mises stress of the annulus fibrosus, and the intradiscal pressures at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) under 7.5 Nm moments were analyzed. Facet contact forces were also compared among three models under the extension and torsion moments. RESULTS: Compared to the intact model, the CL and SPiO models had increased range of motion and annulus stress at both the index segment (L3-4) and the adjacent segments under flexion and torsion. However, the SPiO model demonstrated a reduced range of motion and annulus stress than the CL model. Both CL and SPiO models had an increase of facet contact force at the L3-4 segment under the torsion moment compared to that of the intact model. Under the extension moment, however, three models demonstrated a similar facet contact force even at the L3-4 model. CONCLUSION: Both decompression methods lead to postoperative segmental instability compared to the intact model. However, SPiO technique leads to better segmental stability compared to the CL technique.
PURPOSE: The purpose of this study was to evaluate and compare the biomechanical behavior of the lumbar spine after posterior decompression with the spinous process osteotomy (SPiO) technique or the conventional laminectomy (CL) technique using a finite element (FE) model. MATERIALS AND METHODS: Three validated lumbar FE models (L2-5) which represented intact spine and two decompression models using SPiO and CL techniques at the L3-4 segment were developed. In each model, the ranges of motion, the maximal von Mises stress of the annulus fibrosus, and the intradiscal pressures at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) under 7.5 Nm moments were analyzed. Facet contact forces were also compared among three models under the extension and torsion moments. RESULTS: Compared to the intact model, the CL and SPiO models had increased range of motion and annulus stress at both the index segment (L3-4) and the adjacent segments under flexion and torsion. However, the SPiO model demonstrated a reduced range of motion and annulus stress than the CL model. Both CL and SPiO models had an increase of facet contact force at the L3-4 segment under the torsion moment compared to that of the intact model. Under the extension moment, however, three models demonstrated a similar facet contact force even at the L3-4 model. CONCLUSION: Both decompression methods lead to postoperative segmental instability compared to the intact model. However, SPiO technique leads to better segmental stability compared to the CL technique.
Entities:
Keywords:
Lumbar spinal stenosis; conventional laminectomy; finite element model; spinous process osteotomies
Authors: Risheng Xu; Matthew J McGirt; Scott L Parker; Mohamed Bydon; Alessandro Olivi; Jean-Paul Wolinsky; Timothy F Witham; Ziya L Gokaslan; Ali Bydon Journal: Spine (Phila Pa 1976) Date: 2010-05-01 Impact factor: 3.468
Authors: Ali Bydon; Risheng Xu; Scott L Parker; Matthew J McGirt; Mohamad Bydon; Ziya L Gokaslan; Timothy F Witham Journal: Spine J Date: 2010-05-20 Impact factor: 4.166