新型无尾帽自锁式椎弓根钉的设计与有限元力学分析
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摘要
目的设计新型无尾帽自锁式椎弓根钉,建立腰椎后路融合新型椎弓根钉内固定有限元模型并进行力学分析。方法在传统椎弓根钉设计基础上,对尾帽旋转锁定方式进行优化,无尾帽自锁式椎弓根钉锁紧部分设计为螺钉座及紧固座,在固定连接棒的操作中实现外力提拉一步锁定。建立L_(4、5)后路椎间融合新型椎弓根钉内固定有限元模型,分析腰椎前屈、后伸、侧弯、旋转时椎弓根钉的受力情况。结果新型椎弓根钉内固定最大应力值:前屈2.92×10~(7 )N/m~2,后伸2.97×10~7N/m~2,侧弯3.12×10~7N/m~2,旋转2.89×10~7N/m~2。在前屈、后伸、侧弯及旋转情况下应力集中在螺钉中部及钉棒交界处,以钉棒交界处最为显著。不同工况下腰椎各方向活动度均下降,以屈伸活动时最为显著。结论新型无尾帽自锁式椎弓根钉摒弃了传统椎弓根钉尾帽垂直加压锁定方式,零切迹、一体式锁定设计体现出良好的手术操作便利性,具有良好的临床应用前景。此外,有限元分析新型椎弓根钉受力特点可以为后期生物力学测试及疲劳试验提供数据支持。
ObjectiveTo design a new type of tail-capless self-locking pedicle screw,set up the finite element model of posterior lumbar integrating the new pedicle screw internal fixation and conduct the mechanical analysis.Methods Based on the traditional pedicle screw design,the rotation locking mode of the tail cap was optimized.The locking part of tail-capless self-locking pedicle screw was designed with screw seat and fastening seat,which achieved one-step locking by external lifting force in fixing the connecting rod.The finite element model of L_4and L_5posterior lumbar integrating the new pedicle screw internal fixation was established to analyze the stress of lumbar pedicle screw during anterior flexion,posterior extension,lateral flexion and rotation.ResultsThe maximum stress values of the new pedicle screw internal fixation were2.92×10~7N/m~2during anterior flexion,2.97×10~7N/m~2for posterior extension,3.12×10~7N/m~2for lateral flexion,and 2.89×10~7N/m~2during rotation respectively.In the cases of anterior flexion,posterior extension,lateral flexion and rotation,the stress was concentrated in the middle of the screw and the junction of the screw and rod,most concentrated in the junction of the screw rod.The activity of lumbar spine decreased in all directions under different operating conditions,demonstrating significant decrease shown during flexion and extension.Conclusion The new type of tail-capless self-locking pedicle screw no longer adopts the tail cap vertical condensation locking mode of traditional pedicle screw,and the zero-notch integrated locking design reflects good convenience for surgical operation and has a broad prospect of clinical application.In addition,finite element analysis about the stress characteristics of the new pedicle screw can provide data support for the later biomechanical test and fatigue test.
ObjectiveTo design a new type of tail-capless self-locking pedicle screw,set up the finite element model of posterior lumbar integrating the new pedicle screw internal fixation and conduct the mechanical analysis.Methods Based on the traditional pedicle screw design,the rotation locking mode of the tail cap was optimized.The locking part of tail-capless self-locking pedicle screw was designed with screw seat and fastening seat,which achieved one-step locking by external lifting force in fixing the connecting rod.The finite element model of L_4and L_5posterior lumbar integrating the new pedicle screw internal fixation was established to analyze the stress of lumbar pedicle screw during anterior flexion,posterior extension,lateral flexion and rotation.ResultsThe maximum stress values of the new pedicle screw internal fixation were2.92×10~7N/m~2during anterior flexion,2.97×10~7N/m~2for posterior extension,3.12×10~7N/m~2for lateral flexion,and 2.89×10~7N/m~2during rotation respectively.In the cases of anterior flexion,posterior extension,lateral flexion and rotation,the stress was concentrated in the middle of the screw and the junction of the screw and rod,most concentrated in the junction of the screw rod.The activity of lumbar spine decreased in all directions under different operating conditions,demonstrating significant decrease shown during flexion and extension.Conclusion The new type of tail-capless self-locking pedicle screw no longer adopts the tail cap vertical condensation locking mode of traditional pedicle screw,and the zero-notch integrated locking design reflects good convenience for surgical operation and has a broad prospect of clinical application.In addition,finite element analysis about the stress characteristics of the new pedicle screw can provide data support for the later biomechanical test and fatigue test.
引文
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[11]刘伟,杨康胜,杨文娜,等.经皮骨水泥螺钉内固定结合PVP治疗老年骨质疏松性椎体压缩骨折[J].中国骨与关节损伤杂志,2017,32(9):958-960.
[12]石磊,王陵,雷伟,等.低弹性模量膨胀螺钉在骨质疏松绵羊的体内研究[J].中国骨质疏松杂志,2011,17(9):761-765.
[13]Kim Y,Kim TW.Finite element analysis of the effects of pedicle screw fixation nut loosening on lumbar interbody fusion based on the elasto-plateau plasticity of bone characteristics[J].Spine(Phila Pa 1976),2010,35(6):599-606.
[14]万磊,李义凯.有限元方法在腰椎研究中的应用[J].中国骨与关节损伤杂志,2006,21(2):158-160.
[15]Ivanov AA,Kiapour A,Ebraheim NA,et al.Lumbar fusion leads to increases in angular motion and stress across sacroiliac joint:a finite element study[J].Spine(Phila Pa 1976),2009,34(5):E162-169.
[2]赵磊.脊柱胸腰段骨折术后椎弓根螺钉断裂及弯曲松动的原因分析[J/CD].世界最新医学信息文摘:电子版,2015,15(14):63.
[3]Rohlmann A,Boustani HN,Bergmann G,et al.A probabilistic finite element analysis of the stresses in the augmented vertebral body after vertebroplasty[J].Eur Spine J,2010,19(9):1585-1595.
[4]Guo LX,Zhang YM,Zhang M.Finite element modeling and moda analysis of the human spine vibration configuration[J].IEEE Trans Biomed Eng,2011,58(10):2987-2990.
[5]Mas Y,Gracia L,Ibarz E,et al.Finite element simulation and clinical follow-up of lumbar spine biomechanics with dynamic fixations[J].PLoS One,2017,29,12(11):e0188328.
[6]Henao J,Labelle H,Arnoux PJ,et al.Biomechanical simulation of stresses and strains exerted on the spinal cord and nerves during scoliosis correction maneuvers[J].Spine Deform,2018,6(1):12-19.
[7]Carpenter RD.Finite element analysis of the hip and spine based on quantitative computed tomography[J].Curr Osteoporos Rep,2013,11(2):156-162.
[8]Chen HC,Wu JL,Huang SC,et al.Biomechanical evaluation of a novel pedicle screw-based interspinous spacer:a finite element analysis[J].Med Eng Phys,2017,46:27-32.
[9]Zhou Z,Wei F,Huang S,et al.In vivo magnetic resonance imaging evaluation of porous tantalum interbody fusion devices in a porcine spinal arthrodesis model[J].Spine(Phila Pa 1976),2015,40(19):1471-1478.
[10]Chang CM,Lai YS,Cheng CK.Effect of different inner core diameters on structural strength of cannulated pedicle screws under various lumbar spine movements[J].Biomed Eng Online,2017,16(1):105.
[11]刘伟,杨康胜,杨文娜,等.经皮骨水泥螺钉内固定结合PVP治疗老年骨质疏松性椎体压缩骨折[J].中国骨与关节损伤杂志,2017,32(9):958-960.
[12]石磊,王陵,雷伟,等.低弹性模量膨胀螺钉在骨质疏松绵羊的体内研究[J].中国骨质疏松杂志,2011,17(9):761-765.
[13]Kim Y,Kim TW.Finite element analysis of the effects of pedicle screw fixation nut loosening on lumbar interbody fusion based on the elasto-plateau plasticity of bone characteristics[J].Spine(Phila Pa 1976),2010,35(6):599-606.
[14]万磊,李义凯.有限元方法在腰椎研究中的应用[J].中国骨与关节损伤杂志,2006,21(2):158-160.
[15]Ivanov AA,Kiapour A,Ebraheim NA,et al.Lumbar fusion leads to increases in angular motion and stress across sacroiliac joint:a finite element study[J].Spine(Phila Pa 1976),2009,34(5):E162-169.