RESUMO
BACKGROUND:The Coflex is widely used in China, but it has a high complication rate of spinous process fracture. OBJECTIVE:With the help of finite element analysis, to verify if rigid restriction of spinous process contacts in modified Coflex design is semi-rigid restriction so as to reduce the stress of spinous process in spine flexion and extension, lateral bending and rotation and to decrease the risk of spinous process fracture. METHODS:The images were extracted from patients who had undergone abdomen CT scans in the Beijing Chaoyang Hospital affiliated to Capital Medical University. Three-dimensional finite element model of lumbar spine was established. The Coflex model and the corresponding modified Coflex model were established and then simplified in the SolidWorks software of CAD. Tensile force, shearing force and axial rotating force in resting state were analyzed in ANSYS software. RESULTS AND CONCLUSION:Under tensile force, transversal shearing force and axial rotating force, compared with Coflex system, the stress of spinous process model was reduced in the modified system (P < 0.01). These findings indicate that the forces of the modified model are superior to the force of Coflex. It can reduce stress in the spinous process under stresses and diminish the occurrence of spinous process fractures.