寰枢侧块钉板固定术第1颈椎侧块螺钉置人准确性的分析

目的探讨在无法做正位透视监测的情况下,后路寰枢侧块钉板固定术中在寰椎侧块置钉的准确性。方法术中探查寰椎侧块内缘、间接确定寰椎侧块螺钉穿刺点。收集已行寰枢椎侧块钉板固定术的159例患者的术后CT,从冠状位和轴位CT,观察记录螺钉在寰椎侧块内的位置。在寰椎的CT轴位像上将侧块分为3个区域：A区相当于寰椎侧块上关节面投影区,螺钉在此区域内固定强度最可靠;B区位于上关节面投影区周缘的骨质内（B1内侧,B2外侧）,螺钉在此区域内固定强度不可靠;C区位于侧块以外（C1椎管内,C2横突孔内）,固定依赖于寰椎前弓或寰椎横突,稳定性较差,且有可能损伤脊髓或椎动脉。结果159例患者共置入螺钉318枚,其中308枚位于A区,占96．9％;3枚位于B1区,2枚位于B2区,占1．6％;5枚位于C1区,占1．6％。所有患者在术后4个月随访时寰枢椎后弓间植骨都已融合。结论术中通过探查寰椎侧块内缘、间接确定螺钉穿刺点的方法可准确地将螺钉置入寰椎侧块。     

寰椎侧块-枢椎椎板螺钉固定的有限元分析

目的:建立寰椎侧块-枢椎椎板螺钉固定的三维有限元模型并进行有限元分析,探讨其生物力学特性。方法:通过CT扫描获取1例健康成年男性寰枢椎图像信息,应用VTK软件及ABAQUS软件构建寰椎侧块-枢椎椎板螺钉固定的三维有限元模型,观察中立、前屈/后伸、侧弯、旋转、前后平移等载荷下固定系统的应力变化,分析寰枢侧块-枢椎椎板螺钉固定系统的生物力学特性。结果:所建立的有限元模型逼真地描绘了寰椎侧块-枢椎椎板螺钉固定系统的结构特点,共包含183363个节点(椎骨130982个,螺钉52381个),116082个单元(椎骨83776个,螺钉32306个)。在不同运动状态下,螺钉应力分布主要集中在螺钉置入骨质部分的根部周围和钉棒连接处。前屈载荷时,连接棒从头端至尾端的应力逐步减小,在寰椎侧块螺钉的钉棒连接处应力最大;其他载荷下连接棒应力分布从头端至尾端逐步增大,至枢椎椎板螺钉的钉棒连接处达到最大。后伸和旋转载荷下,螺钉存在明显的高应力区,各螺钉的应力最大值大于其他运动状态。结论:寰椎侧块-枢椎椎板螺钉固定系统固定时各螺钉在颈椎旋转及后伸时所受应力明显增加,术后应避免颈椎过度旋转及后伸,以减少螺钉松动和断裂的发生。     

枢椎椎板螺钉联合寰椎椎弓根螺钉固定治疗寰枢椎脱位

目的 评价枢椎椎板螺钉联合寰椎椎弓根螺钉固定融合治疗寰枢椎脱位的临床可行性.方法 对5例枢椎椎弓根细小的寰枢椎脱位患者,在气管插管全身麻醉下施行了枢椎椎板螺钉联合寰椎椎弓根螺钉固定术.枢椎椎板螺钉的进钉点位于棘突两侧椎板交界处,交叉置人对侧椎板内;寰椎椎弓根螺钉的进钉点位于枢椎侧块中线上,距寰椎后弓上缘最少3 mm,内斜10°,上斜5°.螺钉直径3.5 mm,枢椎椎板螺钉长26～32 mm,寰椎椎弓根螺钉长28～32 mm,结合自体髂骨植骨.结果 患者获得随访3～18个月,平均7.5个月.未发生椎动脉、脊髓损伤,术后临床症状得到不同程度的改善,X线、CT复查螺钉位置良好,无松动、断钉,植骨3个月后均达到满意融合.结论 枢椎椎板螺钉联合寰椎椎弓根螺钉固定治疗寰枢椎脱位效果满意,是又一可供选择的寰枢椎后路固定术式.     

人工寰齿关节置换后各寰枢椎部件生物力学性能的有限元分析

目的通过有限元分析方法评估人工寰齿关节置换后寰枢椎各部件的生物力学性能,以便对其结构优化提供理论依据。方法对人体正常新鲜寰枢椎尸体标本和人工寰齿关节行薄层CT扫描,利用Mimics软件、Freeform Plus软件及Ansys软件,模拟临床前路减压术,将人工寰齿关节模型装配于寰枢椎模型上,构建人工寰齿关节置换后寰枢关节几何模型。对实体模型进行网格划分,并在网格模型基础上添加相关韧带结构,最终建立人工寰齿关节置换后寰枢关节的有限元网格模型。给予模型分别施加前屈、后伸、侧屈、旋转4种生理载荷,计算分析不同载荷下人工寰齿关节置换后寰枢椎各部件的应力分布情况。结果在前屈和后伸状态下,枢椎螺钉钉尾处表现高应力,而寰椎螺钉钉尾未出现高应力;在各种运动状态下,应力集中区分别为人工寰齿关节钢板钉孔处和两部件接触处,枢椎钢板与椎骨接触处也出现应力集中。结论人工寰齿关节钢板钉孔处、枢椎螺钉钉尾和寰枢椎部件接触处容易出现应力集中,人工寰齿关节表面需要涂层处理及其材料硬度和耐磨性有待进一步优化。     

寰椎测量及其经后弓侧块螺钉固定通道的研究

目的：提供国人寰椎的数据，探讨经寰椎后弓侧块（类似椎弓根）螺钉固定的可行性。方法：用游标卡尺对50例干燥寰椎标本进行测量。在实验研究的基础上，对5例寰枢椎不稳患者采用经寰椎后弓侧块螺钉和枢椎椎弓根螺钉加钢板内固定，术中用卡尺和量角器测量寰椎后弓进钉点及进钉方向，术后在X光片和CT片上测量经寰椎后弓侧块螺钉通道。结果：测量得出寰椎后弓、侧块、椎动脉沟、后弓进钉点、后弓侧块螺钉通道的轴线长度及进钉方向等参数。临床5例10枚经寰椎后弓侧块螺钉均准确置入寰椎内，无穿破骨皮质或损伤神经血管病例。结论：寰椎具备行经后弓侧块螺钉内固定的条件。     

前路经寰枢关节螺钉内固定生物力学性能的有限元分析

目的:通过有限元分析的方法评估前路经寰枢关节螺钉内固定的生物力学性能。方法:选择一名21岁健康男性志愿者,采用螺旋CT对枕骨底到C3椎体进行层厚1mm的薄层扫描,利用MIMICS 13.0软件、Freeform Plus软件及ANSYS 9.0软件,建立正常上颈椎有限元模型。去除模型中横韧带的所有单元模拟寰枢关节不稳,以枢椎前弓下缘与枢椎椎体侧缘交界点上方4mm处为进钉点,经寰枢关节分别向两寰椎侧块外上角中部置钉,最终建立前路经寰枢关节螺钉内固定治疗寰枢关节不稳的有限元模型。给予模型分别施加前屈、后伸、侧屈、旋转四种生理载荷,观察不同载荷下螺钉的三维运动范围与应力变化,分析前路经寰枢关节螺钉内固定的生物力学性能。结果:前路经寰枢关节螺钉内固定在不同载荷下三维运动范围均较小,但前屈、后伸状态下三维运动范围(0.72°,1.08°)明显大于侧屈、旋转状态(0.39°,0.32°)。不同状态下应力集中区域均为螺钉经寰枢关节部位,最大应力值为10.58×107Pa,出现在后伸状态。结论:前路经寰枢关节螺钉内固定具有可靠的生物力学性能,在侧屈、旋转状态下的力学性能优于前屈后伸状态,螺钉经寰枢关节部位易产生应力集中,为可能的断钉部位,临床应用时应采取有效预防措施。     

后路寰枢椎侧块钉板固定植骨融合术的临床初探

目的：初步报告后路寰枢椎侧块钉板固定植骨融合术治疗寰枢椎不稳定的近期疗效。方法：用特制螺钉经寰椎后弓根部沿寰椎侧块纵轴置入，固定枢椎的螺钉沿枢椎椎弓峡部进入椎弓根，用连接板将寰枢椎固定螺钉的尾端相连接，用螺母锁定，使寰枢椎得到稳定。在寰枢椎后弓间植入松质骨颗粒。结果：治疗10例因齿状突不连而寰枢不稳定的患者，平均随访194个月，1例固定失败而改用枕颈固定，其余9例均获得了骨性融合。1例术后8个月出现了连接板断裂。6例脊髓功能明显改善，3例略有改善，1例无变化。结论：利用寰椎侧块螺钉和枢椎椎弓根螺钉通过连接板锁定可以使寰枢椎得到坚强的三维固定。此方法更适用于因鹅颈畸形而难以施行Magerl术的病例。     

经口咽前路寰枢椎复位钢板的生物力学评价

目的 对经口咽前路寰枢椎复位钢板(Transoralpharyngeal Atlantoaxial Reduction Plate，TARP)。进行生物力学评价。方法 6例寰枢椎新鲜标本，在脊柱三维运动试验机上将四种常用的寰枢前后路融合术与我们自行设计的经口咽前路寰枢椎复位钢板进行对比，分7组：①对照组(完整标本)；②损伤组；③前路寰枢椎复位钢板组；④后路Brooks钢丝组；⑤Magerl Brooks组；⑥Magerl组；⑦前路经枢椎体寰椎侧块螺钉组(ATS)。分别测量其三维运动范围(ROM)。结果 TARP和Magerl Brooks在各个方向上均无显著性差异，ROM值略大于后者，除在侧屈时和旋转与Magerl无显著差异外，二者抗屈伸、侧屈和旋转均强于其它内固定方法。Magerl除在侧屈和旋转范围与Brooks、前路经枢椎体寰椎侧块螺钉的旋转范围无显著差异外，与Brooks和前路经枢椎体寰椎侧块螺钉在其它运动有显著差异，ROM值小于Brooks和前路经枢椎体寰椎侧块螺钉。Brooks和前路经枢椎体寰椎侧块螺钉在各向上均无显著差异。结论 TARP与Magerl Brooks较其它三种临床上常用的前后路寰枢融合手术固定更牢靠，TARP具有良好的生物力学性能。联合后路Magerl Brooks较单用后路Magerl更牢固。前路经枢椎体寰椎侧块螺钉固定与Brooks钢丝效果相当。     

经口咽前路寰枢椎复位钢板的生物力学评价

目的　对经口咽前路寰枢椎复位钢板 (TransoralpharyngealAtlantoaxialReductionPlate ,TARP)。进行生物力学评价。 方法　 6例寰枢椎新鲜标本 ,在脊柱三维运动试验机上将四种常用的寰枢前后路融合术与我们自行设计的经口咽前路寰枢椎复位钢板进行对比 ,分 7组 :①对照组 (完整标本 ) ;②损伤组 ;③前路寰枢椎复位钢板组 ;④后路Brooks钢丝组 ;⑤Magerl +Brooks组 ;⑥Magerl组 ;⑦前路经枢椎体寰椎侧块螺钉组 (ATS)。分别测量其三维运动范围 (ROM)。 结果　TARP和Magerl+Brooks在各个方向上均无显著性差异 ,ROM值略大于后者 ,除在侧屈时和旋转与Magerl无显著差异外 ,二者抗屈伸、侧屈和旋转均强于其它内固定方法。Magerl除在侧屈和旋转范围与Brooks、前路经枢椎体寰椎侧块螺钉的旋转范围无显著差异外 ,与Brooks和前路经枢椎体寰椎侧块螺钉在其它运动有显著差异 ,ROM值小于Brooks和前路经枢椎体寰椎侧块螺钉。Brooks和前路经枢椎体寰椎侧块螺钉在各向上均无显著差异。结论　TARP与Magerl+Brooks较其它三种临床上常用的前后路寰枢融合手术固定更牢靠 ,TARP具有良好的生物力学性能。联合后路Magerl+Brooks较单用后路Magerl更牢固。前路经枢椎体寰椎侧块螺钉固定与Brooks钢丝效果相当     

寰椎一体式椎板钩与枢椎椎板钉组合应用于非对称内固定生物力学研究

目的本文报道设计一新型寰枢椎内固定组合,并在尸体标本进行生物力学试验,有一定的临床指导意义。方法将6具新鲜尸体颈椎标本置于2Nm载荷下,运用脊柱三维运动测量系统测量C1-2节段的三维运动范围(Range Of Motion,ROM),并将之进行两两对比。实验依完整组、失稳组、双侧寰椎侧块螺钉联合枢椎椎弓根螺钉内固定(Harms技术)组、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组、一侧寰椎一体式椎板钩+枢椎椎板钉联合对侧寰椎侧块螺钉+枢椎椎弓根螺钉内固定组的顺序进行。结果失稳组ROM较完整组显著增加,内固定后ROM显著减小,三种内固定组中: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组在旋转和侧屈方向上具有最小的ROM,双侧寰椎侧块螺钉联合枢椎椎弓根螺钉内固定组在屈伸运动方向上有最小的R0M。一侧寰椎一体式椎板钩+枢椎椎板钉联合对侧寰椎侧块螺钉+枢椎椎弓根螺钉内固定组ROM在旋转、侧屈以及屈伸方向上均较另外两组大,但差异均无统计学意义。结论寰椎一体式椎板钩与枢椎椎板钉组合非对称内固定可提供良好的生物力学稳定性。     

经口咽前路寰枢椎蝶形钢板系统的设计及生物力学评估

目的　设计经口咽前路寰枢椎蝶形钢板内固定系统 ,评价其生物力学性能。方法　设计研制各种型号经口咽前路寰枢椎蝶形钢板、自锁螺钉和复位器等配套器械。选 12具新鲜成年颈椎标本 ,分别进行三维运动范围实验和螺钉拔出力实验。与其他内固定方法作比较分析。结果三维运动范围 ,TARP、Brooks、Magerl、前路经枢椎体寰椎侧块螺钉和Magerl Brooks组的屈伸方向的运动范围分别为平均 4.0、6.2、5 .1、6.6和 3 .7度 ;在侧屈方向的活动范围分别为平均 2 .3、3 .6、2 .7、4.2和 1.8度 ;在旋转活动范围分别为平均 7.4、8.9、8.6、10 .7和 6.0度。结果显示该蝶形钢板固定和Magerl Brooks固定在各个方向上差异均无显著性 (P >0 .0 5 )。其抗屈伸、侧屈和旋转均强于其他 3种内固定方法。寰椎、枢椎和第 3颈椎组的螺钉固定的最大拔出力分别为平均491.5 8、3 96.73和 3 85 .5 3N。结果显示寰椎螺钉的最大拔出力显著高于枢椎和C3 椎体固定螺钉 ,枢椎螺钉与C2 螺钉等效。结论　经口咽前路蝶形钢板系统设计新颖、独特 ,具有良好的生物力学性能。为临床应用提供了生物力学依据。     

异体骨接骨板联合不同螺钉治疗股骨干骨折有限元分析

目的对比分析异体骨接骨板分别联合可吸收螺钉(聚-DL-乳酸)和钛合金螺钉(Ti-6Al-4V)治疗股骨干骨折的应力分布情况,验证可吸收螺钉的强度,为临床提供力学依据。方法利用螺旋CT扫描股骨,将扫描数据以DICOM格式导入mimics软件中,建立股骨三维模型。在proe5.0中建立接骨板模型和螺钉模型(简化为圆柱),装配完成后,导入ansys12.0划分网格、材料赋值,并施加700 N轴向载荷、15 N·m弯曲载荷、15 N·m扭转载荷。结果在三种载荷下6根可吸收螺钉最大主应力的最大值为5.75 Mpa、6根钛合金螺钉最大主应力的最大值为24.9 Mpa;两种不同螺钉固定下,股骨和接骨板的应力分布基本相同。结论可吸收螺钉适应于同种异体骨接骨板的固定,与钛合金螺钉相比,具有减少骨头螺钉孔处的应力遮挡的优点。     

Fixation of diaphyseal fractures with a segmental defect: a biomechanical comparison of locked and conventional plating techniques

BACKGROUND: Locking plates are an alternative to conventional compression plate fixation for diaphyseal fractures. The objective of this study was to compare the stability of various plating with locked screw constructs to conventional nonlocked screws for fixation of a comminuted diaphyseal fracture model using a uniform, synthetic ulna. Locked screw construct variables were the use of unicortical or bicortical screws, and increasing bone to plate distance. METHODS: This biomechanical study compared various construct groups after cyclic axial loading and three-point bending. Results were analyzed via one-way analysis of variance. Displacements after cyclical axial loading and number of cycles to failure in cyclic bending were used to assess construct stability. RESULTS: The constructs fixed by plates with bicortical locked screws withstood significantly more cycles to failure than the other constructs (p < 0.001). Significantly less displacement occurred after axial loading with bicortical locked screws than with bicortical nonlocked screws. Increased distance of the plate from the bone surface, and use of unicortical locked screws led to early failure with cyclic loading for constructs with locked screws. CONCLUSIONS: These results support the use of plating with bicortical locked screws as an alternative to conventional plating for comminuted diaphyseal fractures in osteoporotic bone. Bicortical locked screws with minimal displacement from the bone surface provide the most stable construct in the tested synthetic comminuted diaphyseal fracture model. The results of this study suggest use of plates with unicortical screws for the described fracture is not recommended.     

Accuracy of atlantoaxial transarticular screw insertion

STUDY DESIGN: The accuracy and safety of atlantoaxial transarticular screw insertion were evaluated in clinical cases. OBJECTIVES: To evaluate the accuracy and safety of atlantoaxial transarticular screw insertion under lateral fluoroscopic monitoring without opening the joint. SUMMARY OF BACKGROUND DATA: Atlantoaxial transarticular screw fixation has been reported to be biomechanically superior to posterior atlantoaxial wiring techniques. Several clinical series have been reported in the literature. In some reports, the risk of screw insertion in this technique has been pointed out. MATERIALS AND METHODS: Fifty-six consecutive patients with atlantoaxial instability were treated by transarticular screw fixation. One hundred twelve screw insertions in these 56 patients were assessed by surgical record and computed tomographic examination. One screw could not be inserted because of the difficulty of adequate placement during operation; 111 screws were therefore inserted. Adequate position was defined as when the screw perforated the lateral atlantoaxial joint. RESULTS: In this series, neither vertebral artery injury nor spinal cord injury was experienced clinically. One guide wire was broken during drilling with a cannulated drill. Computed tomographic examination demonstrated that 106 screws perforated the atlantoaxial joint. Therefore, 95.5% of screws were adequately positioned. There were two screws positioned lateral to the joint, two medially, and one anteroinferiorly to the joint. CONCLUSIONS: Atlantoaxial transarticular screw insertion using image intensifier without opening the lateral joint was performed safely, but not accurately, in all cases.     

数字化“定点-定向”双导航模板辅助椎弓根螺钉置钉治疗寰枢椎不稳

目的评价数字化"定点-定向"双导航模板辅助椎弓根螺钉置钉治疗寰枢椎不稳的临床效果。方法回顾性分析2013年9月—2016年12月收治的24例采用数字化"定点-定向"双导航模板辅助行颈椎后路椎弓根螺钉置钉的寰枢椎不稳患者的临床资料。术前CT扫描获取数据经Mimics 10.0软件三维重建后进行寰枢椎后路椎弓根螺钉置钉理想钉道的计算机辅助规划,并根据寰枢椎后方骨性结构表面数据设计个性化"定点-定向"双导航模板。在3D打印机上制作"定点-定向"双导航模板,高温消毒后应用于临床手术辅助置钉。术后根据颈椎X线和CT检查结果评价椎弓根螺钉的位置,并观察植骨融合情况及颈椎稳定性。采用颈部和/或枕骨下疼痛视觉模拟量表(VAS)评分评估患者的临床疗效。结果应用数字化双导航模板为24例患者置入椎弓根螺钉,22例行寰枢椎后路椎弓根螺钉固定,2例行寰枢椎后路椎弓根螺钉并椎板螺钉固定。共置入寰椎椎弓根螺钉48枚,枢椎椎弓根螺钉46枚,枢椎椎板螺钉2枚。术后CT检查示所有螺钉均未穿破钉道骨皮质。所有患者随访6个月,大部分患者颈部疼痛明显缓解,VAS评分由术前(7.78±1.12)分降至术后(2.48±0.55)分,差异有统计学意义(P0.05)。术前肌力下降者术后均不同程度恢复。所有患者均未发生神经、血管损伤等置钉相关并发症。结论数字化"定点-定向"双导航模板不仅能够提高手术置钉的准确性和安全性,还能针对不同类型的寰枢椎不稳提供更合理的置钉方式。     

经口咽前路寰枢椎复位钢板系统的研制与初步临床应用

目的 研制经口咽前路寰枢椎复位钢板系统(TARP),评价其生物力学性能,并进行初步的临床应用观察。方法研制设计一种新型的经口咽前路寰枢椎复位钢板系统,该系统包括蝶形钛合金钢板、自锁螺钉和寰枢椎复位器等配套安装器械。将此系统在12具枕骨～C3新鲜标本卜分别进行了三维运动测试(n=6)和拔出力实验(n=12),比较其生物力学性能,并初步临床应用3例。结果TARP系统设计有巧妙的即时复位饥制。 TARP、Brooks钢丝、Magerl经关节螺钉、前路螺钉以及Brooks钢丝 Magerl经关节螺钉等5组在屈伸方向的平均活动范同分别为4．0、6．2、5．1、6．6、3．7度;在侧屈方向的平均活动范围分别为2．3、3．6、2．7、4．2、1．8度;平均旋转活动范围分别为7．4、8．9、8．6、10．7、6．0度。结果显示TARP的生物力学性能与Brooks钢丝 Magerl经关节螺钉固定等效,较其他3种方法具有更坚强的固定作用。临床应用术后随访平均8．3个月,3例寰椎完全复位,伤口愈合良好,无感染,四肢麻痹消失,肌力恢复,病理反射消失?钢板螺钉未松动。结论TARP设计新颖独到,具有良好的生物力学性能,手术操作简便易行,能达到即时复位,固定效果好,具有良好的应用前景。     

Oblique screws at the plate ends increase the fixation strength in synthetic bone test medium

OBJECTIVE: To test the hypothesis that oblique screws at the ends of a plate provide increased strength of fixation as compared to standard screw insertion. DESIGN: Biomechanical laboratory study in synthetic bone test medium. METHODS: Narrow 4.5-mm stainless steel low-contoured dynamic compression plates were anchored with cortical screws to blocks of polyurethane foam. The fixation strength in cantilever bending (gap closing mode) and torsion was quantified using a material testing system. Different constructs were tested to investigate the effect of the screw orientation at the end of the plate (straight versus oblique at 30 degrees), the plate, and bridging length as well as the number of screws. RESULTS: An oblique screw at the plate end produced an increased strength of fixation in all tests; however, the difference was more significant in shorter plates and in constructs with no screw omission adjacent to the fracture site. Both longer plates and increased bridging length produced a significantly stronger construct able to withstand higher compression loads. Under torsional loading, the fixation strength was mainly dependent on the number of screws. CONCLUSIONS: The current data suggest that when using a conventional plating technique, plate length is the most important factor in withstanding forces in cantilever bending. With regard to resisting torsional load, the number of screws is the most important factor. Furthermore, oblique screws at the ends of a plate increase fixation strength.     

寰枢椎后路经关节螺钉固定术

目的评价参照枢椎椎管内壁行寰枢椎后路经关节螺钉固定（Naged技术）的可行性。方法2002年1月～2005年1月，对31例寰枢椎不稳患者行后路经关节螺钉内固定术，男18例，女13例；平均年龄36．8岁。螺钉置入方法：紧贴枢椎椎管内壁确定距离中线的距离，以枢椎椎板下缘上2帅为进针高度，两线交叉点即为螺钉进针点。螺钉平行矢状面，指向寰枢关节面后缘高度，通过C型臂机侧位像确认螺钉向上倾斜角度。术后结合正、侧位x线片、螺旋CT三维重建及断层扫描图像，评价螺钉置入准确程度。根据螺钉与寰枢椎关节面的位置关系分为A、B、C三区，A区螺钉通过寰椎下关节面；B区螺钉在关节面的前方或后方（前方为B1，后方为B2）；C区为螺钉在关节面的内侧或外侧（内侧为C1，外侧为C2）。结果共置入60枚螺钉。术中无椎动脉、颈脊髓、颈神经根及颅神经损伤。所有患者获得6～18个月（平均9个月）的随访，植骨融合时间为3～12个月，平均5个月，颈脊髓及神经根症状改善明显者3例，部分改善者5例，无改善者1例，无神经症状加重患者。枕颈部疼痛完全缓解者8例，部分缓解者6例，无缓解者2例。60枚螺钉中，A区58枚（96．7％），B1区2枚（3．3％），无B2及C区螺钉。结论参照枢椎椎管壁行寰枢椎后路经关节螺钉固定是安全可靠的。     

The effect of end screw orientation on the stability of anterior instrumentation in cyclic lateral bending.

BACKGROUND CONTEXT: Screw pullout at the proximal or distal end of multilevel anterior instrumentation can occur clinically. Previous laboratory studies have shown that angulation of vertebral body screws increases screw pullout strength and stability in toggling. PURPOSE: To determine the effect of end screw angulation on instrumentation construct stability after cyclic, lateral bending. STUDY DESIGN: A biomechanical study in calf spines comparing two anterior spinal instrumentation constructs, one with parallel polyaxial screws and the other with angled polyaxial end screws. METHODS: Sixteen instrumented constructs were made from eight thoracic (T8-T12) and eight lumbar calf spines (L1-L5). Eight (four lumbar specimens and four thoracic specimens) had five bicortical screws inserted mid-body and parallel to the end plates. The other eight specimens had two screws angled toward the superior end plates of the top two vertebrae; the middle vertebra had a mid-body screw parallel to the end plate, and the bottom two vertebrae had screws angled towards their inferior end plates. The constructs were then cycled in lateral bending, and the displacements of the two instrumentations with a 10 N-m bending load were compared. RESULTS: After 10,000 cycles, constructs with parallel end screws exhibited twice the average displacement than those with angled screws: 5.4 mm versus 2.9 mm (p=.031). CONCLUSION: The use of angled screws at the ends of anterior constructs demonstrated increased construct stability after cycling compared with traditional transverse screws. Although angled screw insertion is technically more difficult and is possible only with specific screw designs, its use might increase instrumentation longevity.