通用型脊柱内固定系统椎弓根螺钉的生物力学测试

目的测试自行设计的通用型脊柱内固定系统(generalspinesystem,GSS)椎弓根螺钉以及SOCON和CCD螺钉置入正常成人椎体标本的最大轴向拔出力及最大旋入力矩,评价GSS螺钉对椎弓根的锚固作用。方法将27个正常成人腰椎椎体标本随机分为3组,每组9个椎体(18侧椎弓根),分别置入GSS、SOCON和CCD椎弓根螺钉,行螺钉拔出试验,测试并记录螺钉的最大旋入力矩和最大轴向拔出力。结果三组螺钉的最大旋入力矩分别为(1.83±0.27)Nm、(2.09±0.51)Nm和(1.66±0.34)Nm,最大轴向拔出力分别为(1131.0±255.4)N、(1034.0±262.3)N和(886.1±152.9)N。GSS螺钉最大轴向拔出力最大,且与CCD螺钉相比差异有非常显著性意义(P<0.01)。结论GSS螺钉具有很强的椎弓根锚固作用。     

膨胀式椎弓根螺钉抗旋出性能的生物力学测试

目的:测试并比较自行设计的膨胀式椎弓根螺钉(Expansive Pedicle Screw,EPS)与USS,Tenor,CDH椎弓根螺钉植入椎体后的最大旋出力矩及旋出180°时能量吸收值,评价EPS螺钉脊柱固定稳定性.方法:30个新鲜小牛腰椎随机分成3组,每组10个椎体(20侧椎弓根),每组均随机在一侧拧入EPS螺钉,对侧分别拧入USS、Tenor,CDH螺钉,旋出螺钉,测试并记录最大旋出扭力矩及旋出180°时能量吸收值.结果:EPS,USS,Tenor,CDH螺钉的最大旋出力矩分别为(3.570±0.914)Nm,(1.607±0.300)Nm,(2.257±0.372)Nm,(2.371±0.348)Nm;能量吸收值分别为(8.277±2.108)J,(3.230±0.559)J,(4.475±0.602)J,(4.441±0.457)J.EPS螺钉的最大旋出力矩及能量吸收值显著大于其它三种螺钉(P值均小于0.01).结论:EPS螺钉较目前使用的USS,Tenor,CDH非膨胀椎弓根螺钉有更好的固定稳定性.     

钉道强化提高椎弓根螺钉固定强度的生物力学研究

目的 评价椎弓根钉道局部强化技术及其结合膨胀式椎弓根螺钉提高椎弓根螺钉固定强度的效果.方法 通过自行设计及加工的钉道局部强化装置,向钉道周壁点状注入CaSO4骨水泥以强化椎弓根钉道.5具新鲜冻存人体脊柱标本,每具随机选取4个腰椎共20个腰椎标本,采用随机区组设计方法分为10个区组.设计四种固定方法:A组(普通椎弓根螺钉)、B组(普通椎弓根螺钉+钉道局部强化)、C组(膨胀式椎弓根螺钉+钉道局部强化)、D组(普通椎弓根螺钉+钉道内灌注CaSO4骨水泥),随机应用在每个区组的2个椎体共4个椎弓根钉道.分别测试每个椎弓根螺钉的最大轴向拔出力及能量吸收值.从剩余腰椎标本中任意取两个腰椎,应用钉道局部强化技术后利用Micro-CT观察钉道周壁微观结构变化.结果 C、D两组的最大轴向拔出力均值及能量吸收值均值高于A组(P＜0.01)及B组(P＜0.05),B组最大轴向拔出力均值及能量吸收值均值高于A组(P＜0.01),C、D两组之间的差异无统计学意义(P＞0.05).结论 钉道局部强化技术可显著提高椎弓根螺钉的固定强度,结合使用膨胀式椎弓根螺钉可进一步提高螺钉的固定强度.     

颈椎椎间孔螺钉、侧块螺钉及椎弓根螺钉的生物力学强度比较

目的比较椎间孔螺钉(paravertebral foramen screws,PVFS)、侧块螺钉(lateral mass screws,LMS)与椎弓根螺钉(pedicle screws,PS)的生物力学强度。方法选取8具新鲜冰冻尸体,男4具、女4具,死亡时年龄(45.3±11.2)岁。CT检查排除骨折、畸形、感染、肿瘤等疾病引起的骨质破坏或其他异常,最终筛选出30个C3~C6颈椎脊椎。将制备完成的颈椎节段标本顺序编号,应用随机数字表法将其随机分为三组,每组10个标本,分别用于双侧置入椎间孔螺钉(4.5 mm×12 mm螺钉)、侧块螺钉(3.5 mm×14 mm)与椎弓根螺钉(3.5 mm×24 mm螺钉)。随机选取一侧进行直接拔出力测试(速度5 mm/min),另一侧进行疲劳测试(位移±1.0 mm,频率1 Hz,循环500次)及残余拔出力测试。结果椎间孔螺钉的直接拔出力为(327.10±17.07)N,侧块螺钉为(305.71±11.63)N,椎弓根螺钉为(635.67±22.82)N。椎间孔螺钉的残余拔出力为(265.62±18.19)N,侧块螺钉为(192.80±17.10)N,椎弓根螺钉为(494.89±41.79)N。椎间孔螺钉、侧块螺钉和椎弓根螺钉的残余拔出力较直接拔出力均有不同程度降低(tPVFS=7.795,tLMS=17.267,tPS=9.349,P<0.001),分别下降了18.8%、36.93%和22.15%。椎弓根螺钉的直接拔出力高于椎间孔螺钉和侧块螺钉(t=34.245,t=40.741,P<0.001),椎间孔螺钉略高于侧块螺钉(t=3.275,P=0.004)。残余拔出力椎弓根螺钉最高,椎间孔螺钉次之,侧块螺钉最小(F=314.619,P<0.001)。椎间孔螺钉的首次循环载荷和首次达到设定位置时载荷均高于侧块螺钉(t=3.625,P=0.002;t=5.388,P<0.001)和椎弓根螺钉(t=2.575,P=0.019;t=2.680,P=0.015),侧块螺钉与椎弓根螺钉的差异无统计学意义(t=0.609,P=0.550;t=1.953,P=0.067)。椎间孔螺钉与椎弓根螺钉的末次循环载荷均高于侧块螺钉(t=5.341,P<0.001;t=3.439,P=0.003),但椎间孔螺钉与椎弓根螺钉的差异无统计学意义(t=1.606,P=0.126)。结论椎间孔螺钉的直接拔出力略高于侧块螺钉,残余拔出力明显高于侧块螺钉,抗疲劳性能与椎弓根螺钉相近并明显优于侧块螺钉,因此,颈椎椎间孔螺钉具有作为侧块螺钉和椎弓根螺钉有效替代的潜能。     

可吸收陶瓷改善椎弓根螺钉稳定性的体外生物力学试验

目的探讨在椎弓根螺钉置入时添加可吸收陶瓷Biobon对椎弓根螺钉稳定性的影响。方法采用28个L3～L5椎体标本,将椎弓根螺钉按标准操作分别置入两侧椎弓根,随机在其中一侧加Biobon。对其中16个椎体测试螺钉最大轴向拔出力F-max和螺钉拔出过程中达到最大轴向拔出力时的能量吸收值E-F-max及螺钉拔出一个螺距2.0mm时的能量吸收值E-2mm。另外12个椎体作梯增负荷的周期抗屈试验。结果同未加Biobon组比较,加入Biobon组的F-max增加了79.7%。E-F-max和E-2mm也分别增加了83.1%和68.2%,两组差异有非常显著性意义Wilcoxon检验,P<0.01。周期抗屈试验中,添加Biobon可使螺钉耐受更强的负荷或在同等负荷下仅产生较小的位移。结论在椎弓根螺钉置入时添加Biobon能显著提高其初始稳定性。     

经皮椎弓根螺钉内固定治疗胸腰椎骨折的生物力学及临床研究

 目的 通过生物力学测试及临床应用对经皮跨伤椎四钉内固定(万向钉固定)与开放手术四钉内固定(单向钉固定)进行比较。方法 取 12具新鲜冰冻小牛腰椎标本 L1~L5节段,随机分为单向钉固定组与万向钉固定组。制备腰椎前中柱损伤模型,比较两组在模型上的运动范围。分别应用 Sextant经皮跨伤椎四钉内固定与开放跨伤椎四钉内固定治疗无神经功能损伤的胸腰椎骨折 25例和 35例,观察其中随访超过 12个月的 11例和 18例的即时复位效果、矫正度丢失情况。结果 (1)生物力学试验院万向钉固定组在各个方向的运动范围均大于单向钉固定组,其中在前屈、后伸方向的差异有统计学意义; 单向钉固定组在前屈、后伸、侧屈方向上的稳定性较完整标本大,差异有统计学意义; 万向钉固定组在前屈、后伸方向上的稳定性与完整标本比较差异无统计学意义。(2)临床应用院两组术前、术后伤椎前缘高度、矢状位 Cobb角的组间差异均无统计学意义; 两组术后伤椎前缘高度、矢状面 Cobb角与术前比较差异均有统计学意义; 末次随访时经皮跨伤椎四钉内固定组伤椎前缘高度丢失(9.9%±5.1%)大于开放跨伤椎四钉内固定组(5.3%±6.8%)。结论 应用 Sextant系统经皮椎弓根螺钉内固定治疗无须神经减压的胸腰椎骨折较开放手术创伤小,但随访中伤椎前缘高度丢失明显。生物力学试验显示其在前屈、后伸运动方向上的强度较弱。     

新型和传统寰椎椎弓根螺钉生物力学稳定性的有限元分析

目的验证新型寰椎椎弓根螺钉离体生物力学稳定性。方法通过CT扫描获取1名健康成年男性志愿者C_(0~3)图像信息,应用Hypermesh 12.0等图像处理软件构建C_(0~3)三维有限元模型并验证其有效性。置入新型寰椎椎弓根螺钉并枢椎椎弓根螺钉或传统寰椎椎弓根螺钉并枢椎椎弓根螺钉建立2种内固定模型,观察其前屈、后伸、侧曲、扭转等加载条件下C_0/C_1、C_1/C_2、C_2/C_3的活动度及内固定的应力分布,比较2种内固定的生物力学特性。结果置入新型螺钉后C_1/C_2扭转活动度比传统螺钉减少20.331 8%,其他加载条件下活动度基本等同。在侧曲与扭转状态下,新型螺钉最大应力均小于传统螺钉,在前屈、后伸时最大应力相当。结论新型螺钉的生物力学稳定性与传统螺钉相当,在对抗扭转活动方面优于传统螺钉;新型螺钉使应力更加合理分散,最大应力减小,有助于降低内固定失效风险。     

椎弓根螺钉设计与其生物力学稳定性的研究进展

<正>椎弓根螺钉内固定术是治疗脊柱疾病的主要方式之一[1],而螺钉松动是椎弓根螺钉内固定术的常见并发症[2],骨质疏松是引起螺钉松动的重要因素之一,其发生率高达60%[3]。有研究报道,当胸腰椎的骨密度时,椎弓根螺钉的生物力学稳定性明显下降[4]。测试椎弓根螺钉的生物力学稳定性指标主要有抗拔出力、疲劳强度、刚度、拧入扭矩[5-9]等。有研究表明,用聚甲基丙     

膨胀式脊柱椎弓根螺钉固定的生物力学研究

目的:测试膨胀式椎弓根螺钉(expansivepediclescrew,EPS)的骨-器械界面强度及耐疲劳强度,评价EPS的脊柱后路固定强度。方法:100个新鲜小牛腰椎随机分成A、B、C三组,以USS,Tenor,CDH螺钉为对照螺钉,分别对EPS进行最大旋出力矩实验、轴向拔出实验和翻修实验,记录最大旋出力矩(Tmax)、最大轴向拔出力(Fmax)和翻修后最大轴向拔出力。并在超高分子聚乙烯材料上对螺钉进行150万次的周期载荷疲劳实验。结果:EPS的Tmax、Famx显著大于三种对照螺钉(P<0.01)。EPS翻修时的Fmax亦显著高于对照螺钉(P<0.05)。150万次周期载荷疲劳实验完成后,四种螺钉均未出现疲劳折断现象。结论:EPS较目前常使用的非膨胀椎弓根螺钉有更好的脊柱固定作用及翻修性能,其耐疲劳强度与其它三种螺钉相当。     

颈椎经关节椎弓根螺钉固定与标准椎弓根螺钉固定的生物力学比较

目的 比较颈椎经关节椎弓根螺钉固定和标准椎弓根螺钉固定的拔出强度.方法 取10具新鲜尸体颈椎标本(C_3～T_1),游离成三个颈椎运动节段(C_(3,4),C_(5,6),C_7T_1).在椎体两侧随机进行经关节椎弓根螺钉固定或标准椎弓根螺钉固定,置入直径3.5 mm皮质骨螺钉.经关节椎弓根螺钉固定以上位椎骨侧块外下象限中点为进钉点,在直视椎弓根下,螺钉在冠状面内倾约45°、矢状面尾倾约50°.由上位椎骨下关节突经关节突关节、下位椎骨的椎弓根,进入下位椎骨的椎体内.标准椎弓根螺钉固定以侧块外上象限中点为进钉点,在直视椎弓根下,螺钉方向参考CT测量结果 ,尽量与椎弓根倾斜角度保持一致,在横断面上内倾约45°、矢状面上螺钉指向椎体的上1/3.在生物力学试验机上行拔出强度试验,比较两种螺钉固定的最大轴向拔出力.结果 颈椎经关节椎弓根螺钉固定平均最大轴向拨出力为(694±42)N,标准椎弓根螺钉固定为(670±36)N,两者比较差异有统计学意义(P<0.05).结论 颈椎后路经关节椎弓根螺钉固定的拔出强度大干标准椎弓根螺钉固定,从生物力学强度方面考虑经关节椎弓根螺钉固定可以作为标准椎弓根螺钉固定的一种补充方法.     

Design and biomechanical study of a modified pedicle screw

Objective： In pedicle screw fixation, the heads of monoaxial screws need to be directed in the same straight line to accommodate the rod placement by backing out during operation, which decreases the insertional torque and internal fixation strength. While polyaxial screws facilitate the assembly of the connecting rod, but its ball-in-cup locking mechanism reduces the static compressive bending yield strength as compared with monoaxial screws. Our study aimed to assess the mechanical performance of a modified pedicle screw.
Methods： In this study, the tail of the screw body of the modified pedicle screw was designed to be a cylindershaped structure that well matched the inner wall of the screw head and the screw head only rotated around the cyclinder. Monoaxial screws, modified screws and polyaxial screws were respectively assembled into 3 groups ofvertebrectomy models simulated by ultra high molecular weight polyethylene （UHMWPE） blocks. This model was developed according to a standard for destructive mechanical testing published by the American Society for Testing Materials （ASTM F1717-04）. Each screw design had 6 subgroups, including 3 for static tension, load compression and torsion tests, and the rest for dynamic compression tests. In dynamic tests, the cyclic loads were 25%, 50%, and 75% of the compressive bending ultimate loads respectively. Yield load, yield ultimate load, yield stiffness, torsional stiffness, cycles to failure and modes of failure for the 3 types of screws were recorded. The results of modified screws were compared with those ofmonoaxial and polyaxial screws.
Results： In static tests, results of bending stiffness, yield load, yield torque and torsional stiffness indicated no significant differences between the modified and monoaxial screws （P〉0.05）, but both differed significantly from those ofpolyaxial screws （P〈0.05）. In dynamic compression tests, both modified and monoaxial screws showed failures that occurred at the insertion point of screw body into the UHMWPE block, while the polyaxial screw group showed screw body swung up and down the screw head because of loosening of the ball-in-cup mechanism.
Conclusions： The modified screw is well-designed and biomechanically improved. And it can provide sufficient stability for segment fixation as monoaxial screws.     

Biomechanical evaluation of an expansive pedicle screw in calf vertebrae

incetheintroductionofthetranspedicularscrewsystembyBoucher ,1theapplicationofthissysteminthetreatmentofdegenerativedisordersandunstablefractures ,tumorsofthespinehasbecomeverypopularinthelasttwodecades.2 Looseningandfailureofthescrewsareamongthemostcommoncomplicationsreported ,especiallyforosteoporosis .3Thesefailuresoftenleadtonon union ,sagittalcollapseoftheconstructandpainfulkyphosis .Revisionisoftennecessary .Increasingthediameterand/orlengthofthepediclescrewseemstobethebestsolution .Howe…     

下颈椎经关节突关节椎弓根螺钉固定的可行性

目的:探讨下颈椎后路经关节突关节椎弓根螺钉固定的可行性和技术参数,为临床应用提供参考。方法:取20具颈椎标本,仔细解剖颈部的后侧和前侧方,清楚显露颈椎侧块和椎弓根。以侧块外下象限的中心点为进钉点,从C3/4～C6/7直视下经关节突关节置入椎弓根螺钉,通过CT重建,测量经关节突关节椎弓根螺钉内固定进钉角度和钉道长度。结果:经关节突关节椎弓根螺钉均成功置入,螺钉固定方向在矢状面呈尾倾,冠状面呈内倾,理想角度为在矢状面尾倾50.3°±4.9°,在冠状面内倾42.8°±4.0°。螺钉钉道长度为(34.1±1.4)mm,各固定节段间略有不同,但差异无统计学意义(P>0.05)。结论:下颈椎后路经关节突关节椎弓根螺钉固定是可行的,但置钉时要求较高的准确性,可以作为颈椎侧块螺钉和椎弓根螺钉固定的一种补充方法。     

Biomechanical evaluation of an expansive pedicle screw in calf vertebrae

The main objective of the present study is to evaluate biomechanically a newly designed expansive pedicle screw (EPS) using fresh pedicles from calf lumber vertebrae in comparison with conventional pedicle screws, (CDH) CD Horizon, Universal Spine System pedicle screw (USS) and Tenor (Sofamor Denek). Pull-out and turning-back tests were performed on these pedicle screws to compare their holding strength. Additionally, revision tests were undertaken to evaluate the mechanical properties of EPS as a rescue revision screw. A fatigue simulation test using a perpendicular load up to 1,500,000 cycles was also carried out. The results showed that the turning back torque (Tmax) and pull-out force (Fmax) of EPS screws were significantly greater than those of USS, Tenor and CDH screws (6.5×40 mm). In revision tests, the Fmax of both types of EPS screws (6.5×40 mm; 7.0×40 mm) were significantly greater than that of CDH, USS, and Tenor screws (P<0.05). Furthermore, no screws were broken or bent at the end of fatigue tests. The findings from the current study suggest that expansive pedicle screws can significantly improve the bone purchase and the pull-out strength compared to USS, Tenor and CDH screws of similar dimensions before and after a failure simulation.     

Comparison of therapeutic effect between percutaneous kyphoplasty and pedicle screw system on vertebral compression fracture

Objective: To compare the clinical efficacy of percutaneous kyphoplasty ( PKP) with pedicle screw system (PS) in the treatment of vertebral compression fracture (VCF). Methods: Eighty-six patients with VCF were treated either by PKP (Group A, n = 30)) or PS ( Group B, n = 56). The anterior, intermediate, and posterior heights of the vertebrae body , visual analogue pain scale( VAS) before and after operation, the duration of operation, and amount of blood loss between two groups were compared. Results: No statistical difference was noted regarding the vertebral height between two groups. Significant difference was seen in VAS, duration of operation and amount of blood loss between the two groups (P<0.0l ). Conclusions: Percutaneous kyphoplasty has the similar therapeutic efficacy with pedicle screw system in treatment of VCF with a minimal invasion, less operation time and blood loss. For those with posterior wall destruction, PS is deemed favorable.     

椎弓根内固定技术的远期疗效评价

目的评价椎弓根内固定技术治疗不同类型脊柱疾患的临床效果及安全性.方法回顾分析475例各种脊柱疾患经椎弓根内固定手术的临床资料,其中男216例,平均年龄(49.1±16.5)岁;女259例,平均年龄(48.7±13.9)岁.包括腰椎滑脱217例,腰椎管狭窄76例,退变性腰椎不稳32例,胸腰椎骨折72例,脊柱侧凸60例,其他18例.采用椎弓根内固定技术包括Dick 55例,Steffee79例,CD 54例,RF 82例,DRFS 59例,TSRH 29例,USS 19例,SOCON 44例,Dynalock 24例,Diapson22例,Tenor 5例,CDH 3例.融合范围一个节段310例,二个节段96例,三个节段9例,与钩合用60例.结果428例(占90.1%)获(6.0±3.7)年随访.退变性腰椎滑脱、峡部裂性腰椎滑脱、腰椎管狭窄、退变性腰椎不稳及胸腰椎骨折患者术后的神经功能改善率分别为79.9%、87.9%、77.0%、89.3%和62 7%;脊柱活动改善率分别为90.5%、90.9%、83.6%、92.9%和52.5%;腰背痛改善率分别为89 9%、87.9%、85.2%、89.3%和84.8%;下肢疼痛改善率分别为93 9%、90 9%、93.4%、92.9%和79 7%.退变性腰椎滑脱、峡部裂性腰椎滑脱及胸腰椎骨折的椎体复位满意率分别为90.5%、87 9%和91 5%.SOCON技术对滑脱椎体复位满意率最高,为92.3%;其次是RF,为90.8%;Dick、Steffee及DRFS技术复位满意率为81.2%;其余内固定技术对滑脱椎体的复位均不满意.并发症共90例,其中术中并发症26例,发生率为6.1%;术后并发症64例,发生率为1 5 0%.结论椎弓根内固定技术可提供短节段脊柱内固定,临床效果满意,脊柱融合率高,并发症的发生与掌握椎弓根内固定技术的熟练程度有关.