枢椎椎板螺钉与椎弓根螺钉抗拔出强度的比较

目的:比较枢椎椎板螺钉与枢椎椎弓根螺钉的抗拔出强度,为临床应用枢椎椎板螺钉固定提供生物力学依据。方法:在7具成年男性新鲜尸体枢椎标本上进行枢椎单皮质椎弓根螺钉和双皮质椎板螺钉固定,测试螺钉拔出力。结果:单皮质枢椎椎弓根螺钉的最大拔出力平均为875.3±403.2N,双皮质枢椎椎板螺钉的最大拔出力平均为679.5±308.2N;椎弓根螺钉的最大拔出力大于椎板螺钉,但二者之间无统计学差异。结论:枢椎椎板螺钉进行双皮质固定具有可靠的力学固定强度,可作为枢椎椎弓根螺钉的补充固定技术。     

寰椎后路单或双层皮质骨螺钉固定强度的生物力学评价

目的:测量单层皮质骨和双层皮质骨寰椎侧块螺钉固定与寰椎椎弓根螺钉固定的强度,为临床选择寰椎后路螺钉固定的方式提供生物力学依据。方法:利用12例新鲜的寰椎和第三颈椎标本,进行单层皮质骨和双层皮质骨的椎弓根螺钉或侧块螺钉固定,测试并比较其螺钉拔出强度。结果:双层皮质骨寰椎椎弓根螺钉固定的拔出力最大,为1757.0±318.7N;单层皮质骨寰椎椎弓根螺钉固定(1192.5±172.6N)与双层皮质骨寰椎侧块螺钉固定(1243.8±350.0N)及单层皮质骨C3椎弓根螺钉固定(1121.6±224.6N)的拔出力之间均无明显差异。结论:应用寰椎侧块螺钉固定时宜选用双层皮质骨螺钉固定,而寰椎椎弓根螺钉固定选用单层皮质骨螺钉即可。     

枢椎棘突螺钉与椎弓根螺钉固定的生物力学拔出力比较

目的 比较枢椎棘突螺钉和椎弓根螺钉的生物力学拔出力强度.方法 取8具新鲜尸体枢椎标本(C2).于椎体两侧随机进行枢椎棘突螺钉和椎弓根螺钉固定,置入直径为4.0 mm的皮质骨螺钉.枢椎棘突螺钉进钉点选择为棘突的基底部、棘突及椎板的交界处,进钉角度为水平置钉,螺钉由对侧棘突基底部穿出,形成双层皮质固定;枢椎椎弓根螺钉在直视椎弓根下置钉.置钉后行拔出强度实验,比较2种螺钉的最大轴向拔出力强度.结果 枢椎棘突螺钉的平均拔出力强度为(387.56±137.73)N,稍小于枢椎椎弓根螺钉的平均拔出强度(465.25±214.32)N,差异无统计学意义(t=-0.862,P =0.403);枢椎棘突螺钉的平均钉道长度为(21.42±1.14) mm,稍短于枢椎椎弓根螺钉的(23.16±1.01) mm,差异有统计学意义(t=4.368,P ＜0.05). 结论 枢椎棘突螺钉具有椎弓根螺钉相近的生物力学拔出力强度,枢椎棘突螺钉在生物力学上具有应用可行性.     

寰椎侧块螺钉与寰椎椎弓根螺钉的解剖与生物力学对比研究

目的对寰椎侧块螺钉和寰椎椎弓根螺钉进行解剖和生物力学研究,为临床选择寰椎螺钉的固定方式提供依据。方法利用12例新鲜标本的寰椎进行单皮质和双皮质的椎弓根螺钉或侧块螺钉固定,测试比较其螺钉拔出强度和钉道长度。结果寰椎椎弓根螺钉的最大进钉长度为29·79mm±1·68mm,其中10·15mm在寰椎后弓内,19·65mm在寰椎侧块内。寰椎侧块螺钉的最大进钉长度为24·88mm±0·41mm,其进钉点与寰椎后弓后缘的平均距离为9·93mm±1·35mm。双皮质寰椎椎弓根螺钉的拔出力量最大,平均1757·0N±318·7N;单皮质寰椎椎弓根螺钉(1192·5N±172·6N)与双皮质寰椎侧块螺钉(1243·8N±350·0N)无明显差异,单皮质寰椎侧块螺钉最小(794·5N±314·8N)。结论在同时适用寰椎椎弓根螺钉和寰椎侧块螺钉固定的患者,宜首先选择寰椎椎弓根螺钉固定,次选寰椎侧块螺钉固定。     

单侧枢椎椎板螺钉在椎动脉变异的上颈椎不稳中的临床应用

目的：探讨后路寰椎侧块螺钉联合单侧枢椎椎板螺钉＋对侧枢椎椎弓根螺钉固定、自体双皮质骨加压植骨融合术治疗上颈椎不稳伴椎动脉变异的临床疗效。方法：2008年6月至2012年12月,行后路寰椎侧块螺钉联合单侧枢椎椎板螺钉＋对侧枢椎椎弓根螺钉固定、自体双皮质骨加压植骨融合术12例,男8例,女4例,年龄16—77岁,平均47．5岁。术前患者枕颈部活动受限伴或不伴疼痛,VAS评分0-7分,平均3．50±2．71;椎动脉造影或颈椎CTA示单侧椎动脉明显狭窄。观察术中有无神经及血管损伤;术后7d内行X线和CT检查,了解内固定位置;术后随访观察有无内固定松动、断裂失败并发症、复位丢失,以及植骨融合率等。结果：12例单侧枢椎椎板螺钉固定,术中未发生神经和椎动脉损伤。患者颈部VAS评分0．92±0．90,较术前明显减轻（P=0．01）。术后x线示12例患者颈椎序列恢复良好,CT示1例枢椎椎板腹侧皮质侵犯,余位置均良好。12例患者均获得随访,时间6个月～3年;未见内固定松动、断裂和复位丢失等并发症;术后6个月12例均骨性融合。结论：后路寰椎侧块螺钉联合单侧枢椎椎板螺钉＋对侧枢椎椎弓根螺钉固定、自体双皮质骨加压植骨融合术,既避免了传统螺钉固定椎动脉损伤的同时,又克服了部分病例双侧枢椎椎板螺钉时植骨床的不足,在保证良好力学稳定的情况下,可以取得良好的骨性融合率。单侧枢椎椎板螺钉可以作为一种安全有效的补充固定措施应用于椎动脉变异的上颈椎不稳患者中。     

骨科：脊柱

20060305寰椎侧块螺钉与寰椎椎弓根螺钉的解剖与生物力学对比研究，20060306后路寰枢椎经关节螺钉内固定治疗陈旧性齿状突骨折，20060307后路寰椎侧块螺钉结合枢椎椎弓根螺钉固定治疗寰枢椎不稳，20060308手术治疗寰枢椎不稳，20060309颈枕区融合术后并发症的防治。[编者按]     

寰椎椎弓根螺钉置入技术的研究进展

目前寰枢椎后路固定常用的技术有Gallie钢丝、Brooks钢丝、Halifix椎板夹、Apofix椎板钩、Magerl经侧块关节螺钉等方法固定。钢丝联合经关节螺钉（Brook+Magerl术）方法固定能提供坚强的固定和较高的融合率,也有助于通过维持脊柱的力线而使脊髓得到间接减压,但经关节螺钉固定有并发椎动脉损伤的可能,而且不管采用哪种置钉技术,均需处理寰枢椎侧块关节后方的椎静脉丛方可显露进钉点。自从谭明生创造性应用寰椎椎弓根螺钉技术以来,该项技术得到了广泛的应用[1]。Tan等[2]在对50具亚洲裔人寰椎标本进行形态学研究后提出,螺钉的进钉点应位于后弓的背侧,而不是从后弓的下方进入寰椎侧块,螺钉经寰椎后弓、峡部至侧块内,Resnick等[3]称之为寰椎的椎弓根螺钉。寰椎椎弓根螺钉固定技术,即通常所说的经寰椎后弓侧块螺钉固定技术,与寰椎侧块螺钉固定技术不是等同的概念。近年来在寰枢椎后路内固定术中寰枢椎椎弓根螺钉固定技术发展越来越快,显示出其他固定方法无可比拟的优越性。国内外关于寰枢椎椎弓根螺钉固定技术的应用解剖学研究、生物力学研究及临床应用研究的报道屡见不鲜,现综述如下。     

前路经寰枢关节锁定钛板螺钉内固定系统三维稳定性的实验研究

[目的]评价前路经寰枢关节锁定钛板螺钉内固定系统治疗寰枢椎不稳的三维稳定性。[方法]8例颈椎新鲜标本,对每一标本分别测定完整状态、齿状突Ⅱ型骨折、前路经寰枢关节锁定钛板螺钉内固定和后路椎弓根螺钉内固定的三维运动范围,并对结果进行统计学分析。[结果]前路固定的前屈为(1.39±0.26)°,后伸为(1.40±0.22)°,侧屈为(1.43±0.23)°,旋转为(1.77±0.34)°。后路固定的前屈为(1.37±0.23)°,后伸为(1.39±0.20)°,侧屈为(1.41±0.22)°,旋转为(1.77±0.33)°,前路经寰枢关节锁定钛板螺钉固定和后路椎弓根螺钉固定的寰枢椎三维运动范围无显著统计学差异(前屈P=0.930,后伸P=0.952,左右侧屈P=0.947,左右旋转P=0.950)。[结论]前路经寰枢关节锁定钛板螺钉固定术的三维稳定性与后路椎弓根螺钉固定术相当,为寰枢椎不稳患者提供了一种手术治疗选择。     

多种寰枢椎后路钉棒固定技术的临床组合应用

目的评价3种寰椎后路螺钉固定方法和2种枢椎后路螺钉固定方法构成的钉棒组合治疗上颈椎不稳的可行性和临床效果。方法在气管插管全麻下对132例患者施行了寰枢椎后路钉棒固定技术,寰椎进行椎弓根螺钉、部分经椎弓根螺钉或侧块螺钉固定;枢椎进行椎弓根螺钉或交叉椎板螺钉固定。结果全组病例获钉棒固定,其中寰椎螺钉固定采用椎弓根螺钉224枚,部分经椎弓根螺钉36枚,侧块螺钉4枚;枢椎螺钉固定采用椎弓根螺钉240枚,椎板螺钉24枚。术中未发生椎动脉、脊髓损伤。120例患者术后获得随访3～22个月,平均8个月,临床症状得到不同程度的改善;X线片、CT复查螺钉位置良好,无松动、断钉,植骨3～6个月后均达到满意融合。结论寰椎和枢椎螺钉可进行多重组合,为上颈椎后路提供灵活多变的短节段固定,增加了钉棒固定技术的临床适用范围。     

后路侧块和椎弓根螺钉技术治疗寰枢椎不稳

目的:评价寰枢椎后路侧块和椎弓根螺钉徒手置入技术(无须术中影像技术引导)的安全性和可靠性。方法:应用AXIS和VERTEX内固定系统(美国枢法模公司)对17例寰枢椎不稳患者进行后路侧块(椎弓根)螺钉内固定,共置入螺钉68枚。其中男11例,女6例,年龄17～71岁,平均43.5岁。AndersonⅡ型11例(陈旧性骨折4例,新鲜骨折7例),Ⅲ型5例(陈旧性骨折1例,新鲜骨折4例);上颈椎肿瘤1例。AXIS治疗15例,VERTEX治疗2例。结果:术后X线片及CT显示寰枢椎侧块和椎弓根螺钉位置良好,2枚螺钉螺纹轻微穿破寰枢椎侧块(椎弓根)外侧皮质,3枚螺钉螺纹轻微穿破寰椎后弓上侧皮质,但不影响固定强度,也未发现与螺钉相关的神经血管并发症。结论:对寰枢椎X线和CT解剖结构了解的情况下,徒手置入寰枢椎侧块(椎弓根)螺钉行内固定手术是安全可行的。     

The effects of cyclic loading on pull-out strength of sacral screw fixation: an in vitro biomechanical study

STUDY DESIGN: The pull-out strength of sacral screw fixation after cyclic loading was tested using young human cadaveric specimens. OBJECTIVES: To evaluate the effects of fatigue loading on the pull-out strength of medial and lateral unicortical and bicortical sacral screws and to correlate the pull-out strength with sacral bone density and the screw insertion torque. SUMMARY OF BACKGROUND DATA: The immediate biomechanical effects of depth of penetration, screw orientation, and bone density on sacral screw fixation have been studied in aged cadaveric specimens. The effect of cyclic loading on the pull-out strength of sacral screw fixation is unknown, however, and data from young specimens is rare. METHODS: Eleven fresh specimens of human sacrum were used in this study. Bone mineral density at the vertebral body and the ala were determined by peripheral quantitative computed tomography. Seven-millimeter compact Cotrel-Dubousset sacral screws were inserted into the sacrum anteromedially and anterolaterally, both unicortically and bicortically, and the insertion torque for each screw was measured. Cyclic loading from 40 to 400 N was applied to each screw at a frequency of 2 Hz up to 20,000 cycles. Pull-out tests were conducted after completion of the fatigue tests. RESULTS: The average bone density was 0.38 +/- 0.08 g/mL at the S1 body and 0.24 +/- 0.05 g/mL at the S1 ala. The insertion torque and average pull-out force after cyclic loading were significantly higher for bicortical fixation than for unicortical fixation for a particular screw alignment. The pull-out strength and insertion torque of medially oriented fixation was always higher than that for lateral fixation, however, regardless of whether the insertion was unicortical or bicortical. The pull-out force of unicortical and bicortical medial screw fixations after cyclic loading showed significant linear correlations with both the insertion torque and the bone mineral density of the S1 body. CONCLUSIONS: In a young population, screw orientation (anterolateral or anteromedial) was more important in determining pull-out strength than screw depth (unicortical or bicortical) after fatigue loading, anteromedially directed screws being significantly stronger than laterallyplaced screws. Bone mineral density of the S1 body andinsertion torque were good preoperative and intraoperative indicators of screw pull-out strength.     

不同椎弓根螺钉固定及骨水泥强化方法在骨质疏松骶骨上锚定强度的比较

目的:通过比较不同椎弓根螺钉固定及骨水泥强化方法在骨质疏松骶骨上的锚定强度,探讨骶骨椎弓根螺钉松动后的理想补救技术.方法:应用11具成人新鲜骶骨标本,经骨密度测试确认为骨质疏松后,在同一骶骨标本上,依次建立5种骶骨螺钉固定模型,A组,单皮质椎弓根螺钉固定(左侧):B组,双皮质椎弓根螺钉固定(右侧);C组,PMMA钉道强化后单皮质椎弓根螺钉固定(建立于A组螺钉拔出后);D组,PMMA钉道强化后侧翼钉固定(右侧);E组,后凸成形技术支持下的PMMA强化后侧翼钉固定(左侧).应用MTS材料测试机进行轴向拔出测试,记录各种骶骨螺钉固定技术的最大拔出力并进行比较.结果:11具标本的骨密度为0.55～0.79g,cm~2,平均0.71±0.08g/cm~2.A～E组最大拔出力分别为508±128N、685±126N、846±230N、543±121N和702±144N.A组与D组间无显著性差异(P>0.05),且均显著低于B、C和E组(P<0.05);B组与E组间无显著性差异(P>0.05),但两组的拔出力均显著低于C组(P<0.05).结论:在骨质疏松患者的骶骨固定中,双皮质骶骨椎弓根钉较单皮质具有更高的锚定强度.骶骨椎弓根钉一旦发生松动,PMMA钉道强化和后凸成形技术支持下的PMMA强化后的侧翼钉固定均可成为理想的补救手段.     

下颈椎后路3种固定技术的拔出强度研究

目的评价下颈椎后路侧块螺钉、椎弓根螺钉、经关节螺钉3种固定方法的拔出强度。方法6具新鲜颈椎尸体标本（C3～C7）,分别用侧块螺钉Roy-Camille法（LMS）、椎弓根螺钉（TPS）和经关节螺钉植入法（TAS）拧入螺钉,使用万能材料实验机,以100、200、300、400、500、600N分级加载,以18mm/min加载速度进行螺钉拔出实验,测试其最大拔出力、最大拔出能量。结果LMS最大拔出力为（426±38）N,最大拔出能量为（5.26±0.39）J;TPS最大拔出力为（502±42）N,最大拔出能量为（7.18±0.67）J;TAS最大拔出力为（482±40）N,最大拔出能量为（6.68±0.47）J。LMS的最大拔出力和最大拔出能量均小于TPS和TAS（P〈0.05）,而TPS和TAS之间相近,差异无统计学意义（P〉0.05）。结论经关节螺钉拔出强度优于侧块螺钉,而椎弓根螺钉拔出强度最大。     

后凸成形骨水泥强化技术对骶骨钉固定强度的生物力学影响

目的评价后凸成形骨水泥(Polymethylmethacrylate,PMMA)强化技术对骨质疏松情况下骶骨钉固定强度的生物力学影响,为骶骨钉松动选择坚强的补救技术提供依据。方法11具新鲜骶骨标本用于实验,并采用DEXA评价标本骨密度。在同一骶骨标本上,依次建立非PMMA强化和PMMA强化骶骨钉的固定模型如下,A组:单皮质椎弓根钉;B组:双皮质椎弓根钉;C组:传统PMMA强化单皮质椎弓根钉;D组:后凸成形PMMA强化椎弓根钉;E组:后凸成形PMMA强化侧翼钉。在MTS试验机上对五种骶骨钉依次进行轴向拔出测试,记录最大拔出力并比较。结果11具标本的平均骨密度为0.71±0.08g/cm2。A组的螺钉拔出力(508N)显著低于其他4种固定组(P0.05)。B组的螺钉拔出力(685N)与E组(702N)无显著差异(P0.05),但是,两者的拔出力均显著低于C和D组(P0.05)。重要的是,D组(986N)的拔出力显著高于C组(846N)。结论在骨质疏松患者的骶骨固定中,双皮质骶骨椎弓根钉较单皮质具有显著的力学优势。骶骨椎弓根钉一旦发生松动,传统的和后凸成形PMMA强化技术均可成为补救手段,并且后凸成形PMMA强化骶骨椎弓根钉可获得最坚强的锚定。     

A biomechanical analysis of the self-retaining pedicle hook device in posterior spinal fixation

Regular hooks lack initial fixation to the spine during spinal deformity surgery. This runs the risk of posterior hook dislodgement during manipulation and correction of the spinal deformity, that may lead to loss of correction, hook migration, and post-operative junctional kyphosis. To prevent hook dislodgement during surgery, a self-retaining pedicle hook device (SPHD) is available that is made up of two counter-positioned hooks forming a monoblock posterior claw device. The initial segmental posterior fixation strength of a SPHD, however, is unknown. A biomechanical pull-out study of posterior segmental spinal fixation in a cadaver vertebral model was designed to investigate the axial pull-out strength for a SPHD, and compared to the pull-out strength of a pedicle screw. Ten porcine lumbar vertebral bodies were instrumented in pairs with two different instrumentation constructs after measuring the bone mineral density of each individual vertebra. The instrumentation constructs were extracted employing a material testing system using axial forces. The maximum pull-out forces were recorded at the time of the construct failure. Failure of the SPHD appeared in rotation and lateral displacement, without fracturing of the posterior structures. The average pull-out strength of the SPHD was 236 N versus 1,047 N in the pedicle screws (P < 0.001). The pull-out strength of the pedicle screws showed greater correlation with the BMC compared to the SPHD (P < 0.005). The SPHD showed to provide a significant inferior segmental fixation to the posterior spine in comparison to pedicle screw fixation. Despite the beneficial characteristics of the monoblock claw construct in a SPHD, that decreases the risk of posterior hook dislodgement during surgery compared to regular hooks, the SPHD does not improve the pull-out strength in such a way that it may provide a biomechanically solid alternative to pedicle screw fixation in the posterior spine.     

两种长度的颈椎椎弓根螺钉与侧块螺钉拔出试验比较

目的:比较两种长度的颈椎椎弓根螺钉和侧块螺钉的抗拔出力,探讨颈椎经椎弓根短螺钉固定的可行性。方法:5具C3~C5共15节新鲜颈椎标本,用长度为28mm和20mm的皮质骨螺钉分别置入椎弓根,并用20mm的螺钉行侧块双皮质固定,螺钉进入侧块深度约14mm。行拔出试验,比较螺钉的最大轴向拔出力。结果:椎弓根长螺钉的最大拔出力为650N,椎弓根短螺钉为585N,两者比较无显著性差异(P>0.01);侧块螺钉的最大拔出力为360N,与椎弓根短螺钉比较有显著性差异(P<0.0001)。结论:颈椎椎弓根短螺钉固定可提供足够的稳定性,其安全性相对较高。     

寰椎椎弓根显露置钉技术的影像学测量研究

目的 :利用CT三维重建对椎动脉沟后弓高度4 mm的寰椎进行置钉通道相关参数测量,探讨椎弓根显露置钉技术的意义。方法:回顾性分析2015年4月至2015年6月行颈椎CT三维重建检查且排除上颈椎畸形、手术的患者90例,其中单侧或双侧椎动脉沟后弓高度4 mm的51例,共84侧。利用其图像数据行寰椎三维数字化重建,并分别测量置钉通道相关数据。结果:51例患者中,椎动脉沟处后弓最低高度为(3.28±0.51)mm,侧块高度、宽度、与后弓移行处高度均可容纳3.5 mm直径螺钉置入。0°~15°(0°、5°、10°、15°)理想椎弓根螺钉钉道长度依次为(27.36±1.81)、(27.01±1.68)、(27.07±1.75)、(27.48±1.72)mm,椎弓根显露置钉技术钉道长度依次为(23.44±1.79)、(23.87±1.84)、(24.58±1.89)、(25.56±2.01)mm,侧块螺钉钉道长度为(20.78±2.05)mm。螺钉通道5个截面的CT值均值分别为椎弓根螺钉(701.89±141.48)HU、侧块螺钉(599.11±137.33)HU。0°~15°理想椎弓根螺钉通道长度之间差异无统计学意义(P0.05),0°~15°椎弓根显露置钉法钉道长度随内倾角增加而增长(P0.05),且均比侧块螺钉钉道长(P0.05),椎弓根螺钉通道穿过骨质CT值均值高于侧块螺钉通道(P0.01)。结论:利用椎弓根显露置钉技术可完成椎动脉沟处后弓高度4 mm的寰椎置钉,且钉道长度损失不多,穿行骨量较大,预期把持力良好。     

骶骨螺钉四种固定方式的生物力学分析

目的 研究骶骨螺钉固定在承受周期性载荷后的拔出强度,评价前内、前外侧和单、双边皮累钉固定的生物力学作用。方法 对１１具新鲜成人尸体的骶骨行定量ＣＴ（ＱＣＴ）扫描以确定Ｓ１椎体和骶骨翼的骨矿物质密度。ＣＣＤ骶骨螺钉分别放置在骶骨的前内、前是和单、双边皮质等四个位置上,测量螺钉固定时旋入的力矩。对螺钉施加４０～４００Ｎ的垂直周期载荷、载荷频率为２Ｈｚ,加载桨数为２００００次。然后行螺钉拔出试验,获得螺     

Biomechanical advantage of C1 pedicle screws over C1 lateral mass screws: a cadaveric study

Purpose

The established technique for posterior C1 screw placement is via the lateral mass. Use of C1 monocortical pedicle screws is an emerging technique which utilizes the bone of the posterior arch while avoiding the paravertebral venous plexus and the C2 nerve root. This study compared the relative biomechanical fixation strengths of C1 pedicle screws with C1 lateral mass screws.

Methods

Nine human C1 vertebrae were instrumented with one lateral mass screw and one pedicle screw. The specimens were subjected to sinusoidal, cyclic (0.5 Hz) fatigue loading. Peak compressive and tensile forces started from ±25 N and constantly increased by 0.05 N every cycle. Testing was stopped at 5 mm displacement. Cycles to failure, displacement, and initial and end stiffness were measured. Finally, CT scans were taken and the removal torque measured.

Results

The pedicle screw technique consistently and significantly outperformed the lateral mass technique in cycles to failure (1,083 ± 166 vs. 689 ± 240 cycles), initial stiffness (24.6 ± 3.9 vs. 19.9 ± 3.2 N/mm), end stiffness (16.6 ± 2.7 vs. 11.6 ± 3.6 N/mm) and removal torque (0.70 ± 0.78 vs. 0.13 ± 0.09 N m). Only 33 % of pedicle screws were loose after testing compared to 100 % of lateral mass screws.

Conclusions

C1 pedicle screws were able to withstand higher toggle forces than lateral mass screws while maintaining a higher stiffness throughout and after testing. From a biomechanical point of view, the clinical use of pedicle screws in C1 is a promising alternative to lateral mass screws.