Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures

Abstract Objective To compare the biomechanical characteristics of thoracolumbar fractures treated with uniplanar screws, monoaxial screws, and polyaxial screws using finite element analysis. Methods CT data of the thoracolumbar spine T12–L2 from a healthy volunteer were collected, and using finite...

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Main Authors: Shen Cao, Tao Xuan, Chengbao Zhang, Yubing Zhang
Format: Article
Language:English
Published: BMC 2025-06-01
Series:European Journal of Medical Research
Subjects:
Online Access:https://doi.org/10.1186/s40001-025-02785-z
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author Shen Cao
Tao Xuan
Chengbao Zhang
Yubing Zhang
author_facet Shen Cao
Tao Xuan
Chengbao Zhang
Yubing Zhang
author_sort Shen Cao
collection DOAJ
description Abstract Objective To compare the biomechanical characteristics of thoracolumbar fractures treated with uniplanar screws, monoaxial screws, and polyaxial screws using finite element analysis. Methods CT data of the thoracolumbar spine T12–L2 from a healthy volunteer were collected, and using finite element software, models of both normal and fractured spines were created. Three different fixation models were constructed with monoaxial screws (Mps group), polyaxial screws (Pps group), and uniplanar screws (Ups group), respectively. The L2 vertebra was fixed and a compressive load of 150 N and a torque of 10 N•m were applied at the T12 end to simulate flexion, extension, lateral bending, and rotation movements of the spine. The range of motion (ROM) and internal fixation stress within the screws and rods were recorded for each movement direction. Results A finite element model of the healthy human spine T12–L2 was established and validated for accuracy. All three fixation models demonstrated decreased ROM in all tested movements. The UPS group showed the lowest percentage of ROM in flexion, extension, and lateral bending movements, with a mid-range percentage of ROM in rotation, and relatively the best stability. The PPS group had the highest ROM percentages in all directions of movement, with the worst relative stability. The maximum von Mises stress for pedicle screws and rods in all fixation modes occurred in flexion, with the MPS group’s screws showing significantly higher stress peaks in flexion and both rotations than those of the PPS and UPS groups. The rods of the PPS group had significantly lower stress peaks in all motion states compared to those of the MPS and UPS groups. Conclusions Uniplanar screws can effectively distribute stress, reduce the risk of screw and rod breakage, and ensure stability of spinal fixation.
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spelling doaj-art-d7a5025314844fe5be7365bdf01a7ba02025-08-20T03:27:11ZengBMCEuropean Journal of Medical Research2047-783X2025-06-013011910.1186/s40001-025-02785-zFinite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fracturesShen Cao0Tao Xuan1Chengbao Zhang2Yubing Zhang3Department of Spine Surgery, Anhui No. 2 Provincial People’s HospitalDepartment of Spine Surgery, Anhui No. 2 Provincial People’s HospitalDepartment of Spine Surgery, Anhui No. 2 Provincial People’s HospitalDepartment of Spine Surgery, Anhui No. 2 Provincial People’s HospitalAbstract Objective To compare the biomechanical characteristics of thoracolumbar fractures treated with uniplanar screws, monoaxial screws, and polyaxial screws using finite element analysis. Methods CT data of the thoracolumbar spine T12–L2 from a healthy volunteer were collected, and using finite element software, models of both normal and fractured spines were created. Three different fixation models were constructed with monoaxial screws (Mps group), polyaxial screws (Pps group), and uniplanar screws (Ups group), respectively. The L2 vertebra was fixed and a compressive load of 150 N and a torque of 10 N•m were applied at the T12 end to simulate flexion, extension, lateral bending, and rotation movements of the spine. The range of motion (ROM) and internal fixation stress within the screws and rods were recorded for each movement direction. Results A finite element model of the healthy human spine T12–L2 was established and validated for accuracy. All three fixation models demonstrated decreased ROM in all tested movements. The UPS group showed the lowest percentage of ROM in flexion, extension, and lateral bending movements, with a mid-range percentage of ROM in rotation, and relatively the best stability. The PPS group had the highest ROM percentages in all directions of movement, with the worst relative stability. The maximum von Mises stress for pedicle screws and rods in all fixation modes occurred in flexion, with the MPS group’s screws showing significantly higher stress peaks in flexion and both rotations than those of the PPS and UPS groups. The rods of the PPS group had significantly lower stress peaks in all motion states compared to those of the MPS and UPS groups. Conclusions Uniplanar screws can effectively distribute stress, reduce the risk of screw and rod breakage, and ensure stability of spinal fixation.https://doi.org/10.1186/s40001-025-02785-zFinite element analysisUniplanar screwMinimally invasive percutaneous fixationThoracolumbar fracture
spellingShingle Shen Cao
Tao Xuan
Chengbao Zhang
Yubing Zhang
Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
European Journal of Medical Research
Finite element analysis
Uniplanar screw
Minimally invasive percutaneous fixation
Thoracolumbar fracture
title Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
title_full Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
title_fullStr Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
title_full_unstemmed Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
title_short Finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
title_sort finite element analysis of percutaneous uniplanar screw fixation in the treatment of thoracolumbar fractures
topic Finite element analysis
Uniplanar screw
Minimally invasive percutaneous fixation
Thoracolumbar fracture
url https://doi.org/10.1186/s40001-025-02785-z
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AT chengbaozhang finiteelementanalysisofpercutaneousuniplanarscrewfixationinthetreatmentofthoracolumbarfractures
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