【作者】 王明飞；

【导师】 倪斌；

【作者基本信息】 第二军医大学 ， 外科学， 2008， 博士

【摘要】 背景上颈椎是由寰枕、寰枢关节组成的复合体,是连接头颅和躯干的重要结构,其解剖结构与下位颈椎差异明显:寰枕关节与寰枢关节之间没有椎间盘,通过滑膜关节相连,靠强大的韧带结构维持稳定性;黄韧带在上颈椎节段移行为寰枢后膜和寰枕后膜;寰枢椎成骨过程比下位颈椎复杂。独特的解剖结构决定了上颈椎复杂的生理功能:寰枕关节是球窝关节,由枕骨髁关节面和寰椎侧块关节面组成,主要负责矢状面上屈伸运动,运动范围约13^?～25^?;寰枢关节包括外侧和中央两组,其中外侧关节由寰椎侧块下关节面和枢椎外侧上关节面组成,主要承载头颅重力;中央关节由齿状突和寰椎前弓及横韧带组成,承担约占整个颈椎50%的旋转功能。上颈椎韧带足够松弛以完成复杂的屈伸、旋转运动的同时,还要足够坚韧以保护脊髓和椎动脉、承载头颅和抵抗颈部强大的肌肉力量,所以临床上很容易发生不稳或脱位。创伤、炎症、肿瘤以及先天性畸形都能破坏上颈椎骨质、韧带、滑膜关节,导致其不稳或脱位,寰枢椎融合是治疗寰枢椎不稳或脱位的一种有效方法。寰枢椎融合一般分后路融合和前路融合,后路融合一方面显露容易,便于安装内固定;另一方面,颈椎生理性前凸,颈后部肌肉力量明显强于颈前方,头颅重心偏向寰枢椎前方,后路融合符合生物力学张力带原则,所以临床应用广泛。影响植骨融合的因素很多,除了年龄、体质、骨质状况外,主要与生物力学稳定性和植骨方式有关。即时稳定性是骨性融合的基础,坚强的内固定还可以缩短术后外固定的时间或减少外固定的使用,避免长期外固定导致的并发症。寰枢椎固定理念经历了从一点固定、两点固定、直至三点固定;从二维固定到三维固定。植骨方式现在多主张加压植骨,同时增加植骨接触面积。现在常用的寰枢椎固定融合技术主要有:Gallie技术和Brooks技术,Apofix椎板夹固定技术、经关节螺钉技术（Magerl技术）、钉棒和钉板固定技术（将寰椎椎弓根螺钉或侧块螺钉与枢椎椎弓根螺钉通过棒或钢板连接）、还有学者将两种内固定方式联合应用。每种内固定方式都各有其适应症和优缺点,生物力学稳定性最好的是Magerl技术联合后路钢丝或钛缆捆扎植骨块固定,属于三点固定,稳定性强,而且通过捆扎可以将植骨块加压,促进植骨融合,减少外固定时间及强度,但是此中术式操作复杂。倪斌等总结寰枢椎后路融合手术经验,发明了一种新型的寰枢椎后路固定融合方式——双侧经寰枢关节螺钉及寰椎椎板钩固定技术,此项技术结合了经关节螺钉技术和椎板钩技术的优点,操作相对简单,在同一系统内同时完成前后三点固定、加压植骨,充分体现了寰枢椎生物力学的三维固定理念。该内固定方式的生物力学稳定性与双侧经关节螺钉联合Gallie钛缆固定方式相似,但避免了钢丝或钛缆穿越椎板对脊髓的损伤风险。用此种内固定方式治疗寰枢椎不稳或脱位数十例,全部骨性融合,术后不需要坚强外固定,可早期活动,值得推广应用。但该术式所用内固定系统是采用普通颈胸椎挂钩与万向螺钉的组合,并非上颈椎专用,无法适应上颈椎特殊的解剖结构,使用中存在一定问题,比如寰椎椎板钩不贴附、安装程序繁琐、器械之间不匹配等,需要自主设计、研制一套与该术式相应的全新内固定系统。本课题通过干燥标本和影像学方法对国人寰枢椎解剖结构进行测量,并根据国人寰枢椎解剖学测量数据,以双侧经寰枢关节螺钉及寰椎椎板钩内固定技术为理论指导,设计并制作一种新型双侧经寰枢关节螺钉及寰椎椎板钩内固定系统。新型内固定系统其生物力学稳定性如何?本课题将通过离体标本的生物力学测试研究,与其他目前经典的三点固定方式进行各方向活动度的对比,对其生物力学稳定性等进行评估,以期对下一步的临床研究和应用进行理论支持。有限元分析方法引入生物力学领域以来的短短30几年时间里,取得了长足的发展。有限元方法可以弥补尸体生物力学实验的不足,可以定量表达人体系统内部的应力分部情况,同时具有节约成本、可重复性好、避免标本间个体差异等优点,尤其在分析器械生物力学性能方面更具有普通力学实验无法比拟的优越性。本课题在前期成功建立的上颈椎不稳模型基础上,将研制的新型内固定系统加载到寰枢椎不稳模型中进行研究,在接近人体真实的生理情况下评价双侧经寰枢关节螺钉及寰椎椎板钩内固定系统的生物力学特点。通过研究与离体生物力学研究结果进行对比验证,分析内固定系统各部位的应力情况,为新型内固定系统的应用与改进提供依据和指导。目的1.测量国人寰枢椎的相关径线及角度,为新型寰枢椎内固定器的设计及手术方式提供参考。以双侧经寰枢关节螺钉及寰椎椎板钩内固定技术为理论指导,以国人寰枢椎解剖学参数为基础,设计新型寰枢椎后路内固定系统。2.通过离体标本的生物力学测试研究,与其他目前常用的固定方式进行各方向活动度的对比,对其生物力学稳定性等进行评估。3.用有限单元法将双侧经寰枢关节螺钉及寰椎椎板钩固定系统加载至寰枢椎不稳模型中,分析不同工况下内固定的应力分布特点。方法1.对35套正常成人寰枢椎干燥骨标本以及40套正常成人上颈椎CT片进行测量,包括椎寰椎后弓高度、宽度,后结节高度、宽度,寰椎后弓内外侧半距,经关节螺钉钉道长度、上倾角、内倾角等。根据获得的解剖学参数及文献回顾,以双侧经寰枢关节螺钉及寰椎椎板钩内固定技术为指导,自主设计研制新型双侧经寰枢关节螺钉及寰椎椎板钩内固定系统。2.以新鲜冷冻尸体标本为实验对象进行新型颈椎内固定系统的生物力学研究。6具人体颈椎标本按照正常、破坏、TA+G（经寰枢关节螺钉+Gallie钛缆）、TA+H（本研究新型寰枢后路内固定系统）、C2+H（双侧枢椎椎弓根螺钉及寰椎椎板钩内固定系统）、C1+C2（寰枢椎椎弓根螺钉内固定）的顺序,分别进行前屈、后伸、左侧屈、右侧屈、左旋、右旋测试,结果进行统计学处理及分析。3.在前期研究已经建立的上颈椎不稳的三维有限元模型基础上,将本实验研制的新型双侧经寰枢关节螺钉及寰椎椎板钩内固定系统进行加载,分析内固定在前屈、后伸、侧屈和旋转方向上的应力分布情况,并与单纯经关节螺钉内固定进行比较。结果1.左右两侧对比无统计学差异。合并统计后,标本测量的寰椎后弓内侧半距11.74±2.47mm;外侧半距20.49±3.22mm。CT影像测量后弓高度9.5±1.6mm、宽度7.4±1.3mm。钉道长度为:39.6±3.4mm,上倾角为:52.0±4.4⁰,内倾角为9.1±4.0⁰。2.离体标本上生物力学测试显示新型双侧经寰枢关节螺钉及寰椎椎板钩内固定系统在前屈、后伸、侧屈、旋转方向测量中均获得最小的活动度,在后伸方向与经关节螺钉联合Gallie内固定有显著性差异,在旋转方向上与寰枢椎钉棒内固定有显著性差异;双侧枢椎椎弓根螺钉及寰椎椎板钩内固定在前屈、后伸和侧屈方向上的活动度与经关节螺钉联合Gallie内固定相似,无显著性差异,但在旋转方向上大于其他三点固定和钉棒内固定,有显著差异。3.新内固定系统在螺钉经过寰枢关节部位应力集中,前屈和侧屈工况下寰椎椎板钩应力增大;与单纯经关节螺钉内固定相比,新内固定系统中经关节螺钉承担应力在屈伸和侧屈方向明显减少。结论1.显露后弓并进入椎管或切除后弓时,不应超过内侧半距11.74±2.47mm。经关节螺钉置钉时的上倾角为52.0±4.4⁰左右,内倾角为9.1±4.0⁰左右,长度为39.6±3.4mm左右,枢椎椎弓根变异较大,应根据具体病情采取个体化治疗。2.新型寰枢椎内固定系统符合国人寰枢椎解剖要求,起到了三点固定的稳定效果,具有良好的生物力学性能,可以做为寰枢椎不稳治疗的首选。双侧枢椎椎弓根螺钉及寰椎椎板钩内固定器在前屈、后伸和侧屈方向上具有良好稳定性,可以作为寰枢椎不稳治疗的备选方式。3.寰椎椎板钩不但能起到后方固定、限制屈伸的作用,还能加压植骨块,促进植骨融合。寰椎椎板钩可以避免内固定系统中经关节螺钉的应力过于集中,减少了松动或断裂可能。更多还原

【Abstract】 BackgroundThe upper cervical spine includes the occipitoatlantal and the atlantoaxial joint complexes.Anatomic characteristics include the absence of intervertebral discs,the absence of ligament flava,and the distinct shape of C1 and C2.The highly specialized anatomy of this region is designed to provide seemingly paradoxical attribute:loose enough to allow nearly 60%of the cervical spine axial rotation,sufficiently tight to protect the delicate structures of the spinal cord and vertebral arteries,and strong enough to resist muscle forces.Motion is coupled between the two joints which provides a relatively large range of motion between the head and the torso.Motion in the sagittal plane is the primary function at the occipitoatlantal junction and reported on average as being between 13 degrees and 25 degrees.The atlantoaxial complex is composed of two facet joints and the unique atlantodental articulation.Rotation in the atlantoaxial complex represents 50%of the entire cervical spine rotation.Articulation is provided by the synovial joints.The versatile function of the upper cervical spine necessitates numerous synovial joints,and this-together with the complexity of the region-makes it vulnerable.The instability of atlantoaxial complex can result from trauma,malformation, malignancy,or inflammatory diseases such as rheumatoid arthritis.The atlantoaxial fusion is a good choice to treat C1-C2 instability.There is no doubt that the initial strength of the construct is greatest at the time of the surgery and subsequently is reduced in the process of the host response until a final fusion is achieved.Atlantoaxial fusion can be accomplished with anterior approach or posterior approach.Most surgeons prefer posterior approach because of its easy exposure and fixation;for the other hand,the muscle bulk in the neck is notably more massive posteriorly and is related to the tendency of the head to be poisoned in such a way that a center of gravity is positioned anterior to the vertical support provided by the spinal column.Thus it can be seen that atlantoaxial fusions are best served with a dorsal fusion mass.Osseous fusion is due to many reasons including age,health,and the quality of bone, stability,the method of bone grafting,and so on.The most important of which is stability and method of bone grafting.The surgical intervention of atlantoaxial instability developed from one-point fixation,two-point,until to three-point fixation;from two dimensional fixation to three dimensional fixation,rigid internal fixation can reduce the time of adjunctive postoperative immobilization such as a halo vest,avoids complications of external orthosis.Recently studies have showed that the highest stability is provided by the three-point fixations of the atlantoaxial complex.Two main aims of internal stabilization are immediate postoperative stability and long-term stability.The immediate postoperative stability contributes to the duration and acceptability of the postoperative treatment.The long-term stability usually is achieved by bone fusion,for which a rigid internal fixation is considered a main factor for occurrence.The atlantoaxial fixation method includes:Gallie and Brooks technique,Apofix or Halifax lamina clamp,bilateral C1-C2 transarticular screw fixation,direct polyaxial screw fixation to the lateral masses of C1 or the pedicle of C2.To maximize stability,the transarticular screw fixation has to be combined either a Gallie or a Brooks fusion.More recently,Brooks combined with bilateral transarticular screw fixation has become the gold standard for achieving atlantoaxial arthrodesis.But this increase the risk of neural injury caused by the passage of sublaminar wires.A new fixation technique for C1-C2 arthrodesis is presented by NI-bin et al.It consists of a hook construct for the posterior arch of C1 that is rigidly attached to C1-C2 transarticular screws to form an instrument that combines anterior and posterior fixation in the same construct.This bilateral atlantoaxial transarticular screws and atlas laminar hooks technique has the advantage over C1-C2 transarticular screw and Halifax which allows reliable stabilization against motion in six degrees of freedom:anterior-posterior slip as well as extension- flexion,lateral slip as well as lateral bending,and axial translation as well as rotation.Furthermore,bone graft can be compressed tightly between the posterior arch of C1 and lamina of C2 by rod between the hook and screw.The novel technique provides excellent atlantoaxial stability that is equivalent to the Magerl-Brooks construct, but it can avoid risky to place cerclage wire under the C1-C2 lamina.The NI-bin technique obtained satisfied treatment effectiveness in clinical application. But the now available instruments have some problems and are not suitable for Chinese population.For example,the now available laminar hooks are made for thoracic laminar originally and not suitable for atlas posterior arch,the hook and the screw are very difficult to connect,et al.A novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks needs to be designed to meet the technique and anatomy property of Chinese population.The study measured linear and angular parameters of atlas and axis in Chinese population and provide morphological basisi for the fixator design.A novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks was designed and manufactured.An in vitro biomechanical study using cadaveric model were performed to investigate the novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks by comparing with other three different contemporary posterior atlantoxial fixations.Finite element method grown greatly since it was first used for biomechanics study more than 30 years before.It’s an invaluable tool that can supplement experimental research in understanding the clinical biomechanics of the upper cervical spine. Furthermore,because of its reproducibility and repeatability,a fully validated model can be used to analyze detailed parametric studies of novel instrumentation,allowing for the avoidance of otherwise costly experimentation.The destabilized three-dimensional finite element model of the upper cervical spine (C0-C3) established by Doctor Ren is available.The novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks were solid modeled, using commercially available design software,imported to the destabilized model and meshed.The instrumented models were run in flexion,extension,and lateral bending and axial rotation for evaluating the biomechanical properties and the stress of transarticular screw and hook.Objectives1.To measure linear and angular parameters of atlas and axis in Chinese population and provide morphological basisi for the design of the novel posterior atlantoaxial fixator. To design a novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks.2.To investigate the acute stability afforded by the novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks by comparing with other three different contemporary posterior atlantoxial fixations.3.To investigate the stress distributions of the destabilized models with the novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks under quasistatic loading in flexion,extension,lateral bending and rotation. Materials and Methods1.Thirty-five sets of normal adult dry atlas and axis vertebral samples and 40 sets of normal adult CT images of the upper cervical spine were measured.The parameters include posterior atlantal arch width,height,length,inside semi-diameter,outside semi-diameter,the transarticular screw path length,the transarticular screw path angle in the transverse plane and in the sagittal plane.A novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks was designed.2.In this study,6 fresh-frozen human candaveric cervical spines with occiput(C0-C5) were used.Osteoligamentous specimens were tested in their intact condition and destabilizetion via transverse-alar-apical ligament disruptions and were analyzed by the three dimensional motion testing system.The reconstructions tested were TA+G(the transarticular screw-wiring fixations),TA+H(the transarticular screw-C1 hooks fixations), C2+H(the C2 Pedicle screws-C1 hooks fixations),C1+C2(C1-C2 screw and rod fixations).3.The novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks were solid modeled,using commercially available design software, imported to the destabilized three-dimensional finite element model of the upper cervical spine(C0-C3) and meshed.The instrumented models were run in flexion,extension,and lateral bending and axial rotation for evaluating the biomechanical properties and the stress of transarticular screw and hook.The study also evaluated the change of stress of transarticular screws after the atlas laminar hooks were imported.Results1.There was no statistical significance between the left and right side data.The outside semi-diameter was(20.49±3.22)mm.The inside semi-diameter was (11.74±2.47)mm.The image measurements show the posterior atlantal arch width was (7.4±1.3)mm.The transarticular screw path length was(39.6±3.4)mm.The transarticular screw path angle in the transverse plane was(52.0±4.4)~0.The transarticular screw path angle in the sagittal plane was(9.1±4.0)~0.2.The data indicate that destabilization via transverse-alar-apical ligament disruptions significantly increase C1-C2 motion.The ROM values of TA+H were lower than other fixations in all directions.The p values were less than 0.05 for TA+H versus TA+G in extension and for TA+H versus C1+C2 in axial rotation.The ROM values of C2+H were higher than other fixations in al directions.There were no p values less than 0.05 for C2+H versus TA+G in flexion,extension and lateral bending.But the P values were less than 0.05 for C2+H versus TA+H,TA+G and C1+C2 in axial rotation.3.The finite element model predicted that the maximum von Mises stress was in the region where screws penetrated the atlantoaxial facet joints,and the second was located at the junction of the rod and screw.The stress of C1 hook increased in flexion and lateral bending.The stress of transarticular screws decreased in flexion/extension and lateral bending after the atlas laminar hooks were imported.Conclusions1.Exposure range during operation is limited in order to avoid damage of vertebral artery.The transarticular screw should be(39.6±3.4)mm long and be inserted(52.0±4.4)~0 cephalad and(9.1±4.0)~0 lateral.The axis pedicle varied largely and therapy should be individualized treatment.2.The novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks provides the best biomechanical stability.Although the the fixator composed of bilateral C2 Pedicle screws and C1 hooks is not as stable as traditional three-point fixtions,it provides the similar stability with other fixations in flexion, extension and lateral bending.3.The atlas laminar hook add a posterior fixation point,and at the same time which can compress bone graft between the C1 posterior arch and C2 lamina.The atlas laminar hooks fixation can reduce the stress of the transarticular screws.The novel posterior atlantoaxial fixator composed of bilateral transarticular screws and C1 laminar hooks is consistent with the three-dimensional fixation theory and provides excellent atlantoaxial stability.更多还原