The feasibility of short-segment Schanz screw implanted in an oblique downward direction for the treatment of lumbar 1 b
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(2020) 15:537
RESEARCH ARTICLE
Open Access
The feasibility of short-segment Schanz screw implanted in an oblique downward direction for the treatment of lumbar 1 burst fracture: a finite element analysis Jifeng Liu†, Sheng Yang*†, Fei Zhou†, Jianmin Lu, Chunyang Xia, Huanhuan Wang and Chao Chen
Abstract Background: To evaluate the biomechanical properties of short-segment Schanz screw implanted in an oblique downward direction for the treatment of lumbar 1 burst fracture using a finite element analysis. Methods: The Universal Spine System (USS) fixation model for adjacent upper and lower vertebrae (T12 and L2) of lumbar 1 vertebra burst fracture was established. During flexion/extension, lateral bending, and rotation, the screw stress and the displacement of bone defect area of the injured vertebrae were evaluated when the downward inserted angle between the long axis of the screws and superior endplate of the adjacent vertebrae was set to 0° (group A), 5° (group B), 10° (group C), and 15°(group D). There were 6 models in each group. Results: There were no significant differences in the maximum screw stress among all the groups during flexion/ extension, lateral bending, and rotation (P > 0.05). There were no significant differences in the maximum displacement of the bone defect area of the injured vertebrae among all the groups during flexion/extension, lateral bending, and rotation (P > 0.05). Conclusion: Short-segment Schanz screw implanted in an oblique downward direction with different angles (0°/ parellel, 5°, 10°, and 15°) did not change the maximum stress of the screws, and there was a lower risk of screw breakage in all groups during flexion/extension, lateral bending, and rotation. In addition, the displacement of the injured vertebra defect area had no significant changes with the change of angles. Keywords: Lumbar burst fracture, Schanz screw, Oblique downward direction, Biomechanics
Background Burst fractures of the thoracolumbar spine often require surgical treatment; however, there is no uniform standard whether the stenotic spinal canal needs decompression or whether the intraspinal retropulsed bone fragments need to be removed for the fracture combined with nerve injury * Correspondence: [email protected] † Jifeng Liu, Sheng Yang, and Fei Zhou equally contributed to this paper and thus shared the co-first authorship. Department of Orthopaedics, Affiliated Zhongshan Hospital of Dalian University, 6 Jiefang Street, Zhongshan District, Dalian 116001, Liaoning, China
[1–3]. Miyashita et al. [4] found no significant correlation between nerve recovery and percentage of spinal canal stenosis and provided evidences questioning the need to remove the retropulsed bone fragments in thoracolumbar fractures combined with nerve injury. Therefore, a new method that can effectively treat thoracolumbar burst fractures without decompression of the spinal canal remains to be found in the future. Short-segment Schanz screw fixation implanted in an oblique downward direction, which was firstly proposed by us i
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