Ho-Joong Kim1, Kyoung-Tak Kang2, Juhyun Son2, Choon-Ki Lee3, Bong-Soon Chang3, Jin S Yeom4. 1. Spine Center and Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, 166 Gumiro, Bundang-gu, Sungnam, 463-707, Republic of Korea. 2. Department of Mechanical Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, Republic of Korea. 3. Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Hospital, 101 Daehangno, Jongno-gu, Seoul, 110-744, Republic of Korea. 4. Spine Center and Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, 166 Gumiro, Bundang-gu, Sungnam, 463-707, Republic of Korea. Electronic address: highcervical@gmail.com.
Abstract
BACKGROUND CONTEXT: Facet joint orientation and tropism influence the biomechanics of the corresponding segment. Therefore, the sagittal orientation or tropism of the facet joint adjacent to the fusion segment seems a potential risk factor for adjacent segment degeneration. However, there have been no biomechanical studies regarding this issue. PURPOSE: To investigate the association between adjacent facet orientation and facet tropism and stress in adjacent disc/facet joints using finite element (FE) analysis. STUDY DESIGN: An FE analysis. METHODS: Four intact (F50, F55, F60, and FT [facet tropism]) and matched L3-L4 fusion (F50, F55, F60, and FT fusion) models with different facet joint orientation (50°, 55°, 60° relative to the coronal plane, and facet tropism, respectively) at both L2-L3 facet joints were simulated. In each model, intradiscal pressures and facet contact force at the L2-L3 segment were investigated under pure moments and anterior shear force. RESULTS: Compared with the matched-intact model, the F60 fusion model yielded the highest and largest percentage increase of intradiscal pressure at the L2-L3 segment under flexion, torsion moment, and anterior shear force among the F50, F55, and F60 fusion models. F60 fusion model also demonstrated the largest facet contact force under torsion moment among the F50, F55, and F60 fusion models. In all conditions tested, the FT fusion model demonstrated the highest intradiscal pressure and facet contact force of all the models. CONCLUSIONS: Facet joint orientation and tropism at the adjacent segment influences the overstress of the adjacent segment, especially under the clinical circumstance of increased anterior shear force.
BACKGROUND CONTEXT: Facet joint orientation and tropism influence the biomechanics of the corresponding segment. Therefore, the sagittal orientation or tropism of the facet joint adjacent to the fusion segment seems a potential risk factor for adjacent segment degeneration. However, there have been no biomechanical studies regarding this issue. PURPOSE: To investigate the association between adjacent facet orientation and facet tropism and stress in adjacent disc/facet joints using finite element (FE) analysis. STUDY DESIGN: An FE analysis. METHODS: Four intact (F50, F55, F60, and FT [facet tropism]) and matched L3-L4 fusion (F50, F55, F60, and FT fusion) models with different facet joint orientation (50°, 55°, 60° relative to the coronal plane, and facet tropism, respectively) at both L2-L3 facet joints were simulated. In each model, intradiscal pressures and facet contact force at the L2-L3 segment were investigated under pure moments and anterior shear force. RESULTS: Compared with the matched-intact model, the F60 fusion model yielded the highest and largest percentage increase of intradiscal pressure at the L2-L3 segment under flexion, torsion moment, and anterior shear force among the F50, F55, and F60 fusion models. F60 fusion model also demonstrated the largest facet contact force under torsion moment among the F50, F55, and F60 fusion models. In all conditions tested, the FT fusion model demonstrated the highest intradiscal pressure and facet contact force of all the models. CONCLUSIONS: Facet joint orientation and tropism at the adjacent segment influences the overstress of the adjacent segment, especially under the clinical circumstance of increased anterior shear force.
Authors: Liwei Zheng; Yong Cao; Shuangfei Ni; Huabin Qi; Zemin Ling; Xin Xu; Xuenong Zou; Tianding Wu; Ruoxian Deng; Bo Hu; Bo Gao; Hao Chen; Yusheng Li; Jianxi Zhu; Francis Tintani; Shadpour Demehri; Amit Jain; Khaled M Kebaish; Shenghui Liao; Cheryle A Séguin; Janet L Crane; Mei Wan; Hongbin Lu; Paul D Sponseller; Lee H Riley; Xuedong Zhou; Jianzhong Hu; Xu Cao Journal: Bone Res Date: 2018-07-18 Impact factor: 13.567