• Liang Wang, Bangke Zhang, Shuo Chen, Xuhua Lu, Zhi-Yong Li, and Qunfeng Guo.
• Department of Orthopaedics, Changzheng Hospital Affiliated to the Second Military Medical University, Shanghai, China.
• World Neurosurg. 2016 Nov 1; 95: 126-133.

ObjectiveTo develop modified finite element models to simulate degenerative lumbar scoliosis (DLS) based on the normal lumbar spine model and to investigate the facet joint force of the DLS.MethodsA 3-dimensional finite element model of a normal lumbar spine was modified to simulate 3 different Cobb angles conditions (12.3°, 22.2°, and 31.8°). The stresses on the facet joint were calculated on both sides (right and left) of the each vertebra. Changes of stress and asymmetry in contact forces between facet joints in the development of DLS were quantitatively analyzed to better understand the development of DLS and the biomechanical forming mechanism.ResultsThe results show that asymmetric responses of the facet joint forces exist in various postures and that such effect is amplified with larger curve. When the Cobb angle was smaller, the convex side of the facet joints suffered larger force. When the Cobb angle was larger than 20°, the concave side of the facet joints suffered larger force. In the axial-rotation cases, the facet joint compression is less often located on the ipsilateral side than the contralateral side at the same level.ConclusionsWith the asymmetric loading, facet joints compressive deformation appears on the concave side, and it decreases in the effect of the facet joints to limit the vertebral rotation and listhesis. Asymmetric loading on facet joint contact forces accelerates asymmetry in the lumbar spine.Copyright © 2016 Elsevier Inc. All rights reserved.

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