Atlantoaxial vertebral posterior fixation of short-segment graft: increased intensity has few impact on the rotation and flexion-extension movement

doi:10.3969/j.issn.2095-4344.2014.48.025

Abstract

Abstract:

BACKGROUND: Atlantoaxial vertebra is the central region of the life. Due to the unique anatomical structures, the operation in this region is difficult and has high risk. Posterior approach is a commonly used surgical reconstruction on the stability of the upper cervical spine. The best way to fix is short and strong internal fixation, which has strong fixation and causes less affect on the rotation and flexion-extension movement.
OBJECTIVE: To review the technology of atlantoaxial vertebral posterior internal fixation.
METHODS: The first author retrieved articles published until May 2014 on PubMed
(http://www.ncbi.nlm.nih.gov/PubMed) and Wanfang (http://med.wanfangdata.com.cn/) databases, with “upper cervical, internal fixation, atlas and axis, posterior approach” as the key words in English and Chinese. Using different combinations of the key words, a total of 267 articles in English and 189 in Chinese were retrieved. After reading the title and abstract for early screening, repeated and upper cervical unrelated reports in both English and Chinese literature are eliminated. Finally 48 articles were included in the reviews.
RESULTS AND CONCLUSION: Due to the specific anatomy of atlantoaxial vertebra, atlantoaxial internal fixation technology is obviously different from the other cervical vertebra. Lamina depending internal fixation including Gallie technique, Brooks technique, Sonntag technique, lamina clamp, Locksley intersegmental tie bar technique and C2 crossing laminar screw technique. These techniques need the integrity of C1 and C2, and are not available for laminectomy decompression. Besides C2 crossing laminar screw, the rest of the methods require spinal canal invasion operation, and the ability to resist rotation are relatively poor. Lamina independing internal fixation is developed in recent years, including the lateral mass screws, transarticular screw, atlas pedicle screw, axial isthmus screw, and axial pedicle screws. Its characteristic is the application of screws, which greatly enhance biomechanical strength and increase fusion rate, without affecting the lamina decompression. Atlantoaxial area is very close to human body life central, being familiar with the regional anatomy and skilled internal fixation implant technique are essential for successful completion of the surgery in this area.

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程

全文链接：

Key words: cervical vertebra, internal fixator, axis, anatomy

CLC Number:

R318

Miao Jun, Xia Qun. Atlantoaxial vertebral posterior fixation of short-segment graft: increased intensity has few impact on the rotation and flexion-extension movement[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(48): 7849-7854.

Figures/Tables 1

2.1 Gallie融合 Gallie[2]1939年首先报道了这种技术。取单块髂骨，下缘做切迹骑跨在C2棘突上，上面斜靠在C1后弓上。植骨块由钢缆固定，钢缆由C1椎板下穿过，绕在C2棘突上，而没有在C2椎板下穿过，这样可减少脊髓损伤的机会。这种方法提供了良好的屈伸稳定性，但是旋转稳定性较差，不愈合率高达25%。Coyne等[3]对32例非肿瘤性上颈椎失稳患者进行后路融合，其中31例进行了Gallie融合，1例进行了Brooks融合，平均随访4.7年，有6例(19.3%)出现融合失败，其中有2例(6%)还出现了神经症状，作者认为即使术后采用Halo环辅助固定，传统的后路钢丝固定技术也存在较高的失败率。2.2 Brooks融合 Brooks技术是采用两块髂骨块分别放置在C1和C2之间[4]。每个髂骨块上下缘做成斜面形，可以楔形卡在C1和C2椎板间，线缆分别穿过C1和C2椎板下，将骨块绑紧。不仅具有较好的屈伸稳定性，而且较Gallie技术提高了旋转稳定性，融合率可达93%，如果采用Halo环固定，融合率还会提高。Moon等[5]采用Brooks技术对54例齿状突发育不良或骨折造成的寰枢椎失稳患者进行了后路融合，术后进行颈椎布带牵引和颈胸支具固定14周，平均随访15周，有48例出现融合，6例融合失败，融合率达89%，作者认为Brooks融合技术是安全的，如果结合采用双股钢丝固定骨块和颈胸外固定支具，则可达到很高的融合率。 2.3 Sonntag固定 Sonntag对Gallie的技术进行了改良，提高了旋转稳定性，同时避免了Brooks技术双侧椎板下穿钢缆的缺点[6]。Sonntag技术的要点是椎板下钢缆先由C1椎弓下缘向上缘穿过，髂骨块下缘做成H形，上缘做成楔形，卡在C2棘突与C1后弓之间(不像Gallie技术是简单的靠在C1后弓之上)。C2棘突上表面和C1椎弓下表面均进行去皮质处理。线缆绕过髂骨块表面和C2棘突下面做的切迹上。Sonntag推荐患者采用Halo环固定3个月，再用硬围领固定2个月，采用这种处理后，融合率达97%。 2.4 椎板夹考虑到需要在椎板下穿过钢丝，对脊髓存在一定的干扰，Holness于1984年设计了Holifax椎板夹，这种装置有2枚片状的钩子，一个挂在C1后弓上缘，另一个挂在C2椎板下缘，两个钩片尾端用螺钉连接，在C1后弓和C2椎板之间左右两侧分别放置一块合适的三角形断面的植骨块，拧紧螺钉时椎板夹可将C1、C2及植骨块抱紧达到固定效果[7-9]，术中操作相对困难一些。美国Sofamor Danek公司设计的Apofix椎板夹是采用1对上钩和下钩分别钩在C1后弓上缘和C2椎板下缘，于C1后弓和C2棘突之间放置H型骨块，最后上下钩进行加压抱紧[10-11]。这种方法操作更加简便，而且适合C1-C7不同节段的椎板外形。椎板夹法要求椎板完整，优点是不侵入椎管，对脊髓无干扰，如果C1和C2后侧结构明显退变、骨质疏松、Jefferson骨折、Hangman骨折则不适合应用。具有良好的屈伸稳定性，控制旋转力量仍较差，往往需要术后需佩戴硬颈托或Halo固定。 2.5 扣座节段间固定这种技术是中间采用一块棘突钢板固定棘突，两侧植骨用肋骨，通过椎板下钢丝8字固定[12]。不仅可用于寰枢椎短节段固定，也可以用于下颈椎长节段固定融合。通过中间的棘突钢板和两侧8字钢丝固定的肋骨，可达到3点固定，即刻稳定性和各个轴线上的稳定性都很好。 2.6 枢椎椎板交叉螺钉固定 Wright等[13-14]介绍了枢椎椎板交叉螺钉固定技术，于枢椎椎板交叉置入3.5 mm直径螺钉，与C1侧块螺钉结合治疗寰枢椎不稳，适合于椎动脉高跨畸形、椎弓根细小无法置入3.5 mm直径的螺钉、椎弓根明显骨硬化没有髓腔无法置入螺钉、一侧优势椎动脉而对侧椎动脉堵塞等情况，不宜进行寰枢椎经关节突螺钉固定和C2椎弓根螺钉置入的患者。Cassinelli等[15]的解剖学研究表明，枢椎椎板厚度≥ 5 mm有71%，≥ 4 mm有93%，因此为置入螺钉创造了解剖学基础。交叉椎板螺钉置入方法为：在C2棘突与右侧椎板交界中上1/3处开孔为左侧螺钉进钉点，在左侧椎板与C2棘突交界中下1/3处开孔为右侧螺钉进钉点，手钻向对侧椎板钻孔，圆头探针探测深度并确认骨壁完整，丝锥攻丝，置入万向螺钉，以连接棒将其与C1椎弓根钉相连接。与关节突螺钉相比，其生物力学强度前屈、后伸相同，旋转略差。Gorek等[16]的生物力学研究表明，交叉椎板螺钉法固定强度与Harms法寰枢固定法和Magerl经关节突螺钉固定法相同。Lapsiwala等[17]的生物力学研究表明，交叉椎板螺钉法在屈伸和旋转方向的固定强度与其他固定方法一样，在侧屈方向固定强度略小。Ma等[18]采用有限元分析发现C2交叉椎板螺钉和C2椎弓根螺钉固定强度不相上下，两者在生物力学方面没有明显差异。Ma等[19]采用C2交叉椎板螺钉技术治疗寰枢椎失稳35例，术中未出现内固定器械相关的血管损伤和神经损伤并发症，术后CT扫描显示有10例出现椎板背侧皮质受侵，而腹侧皮质均完好无侵及，随访患者未出现松动，认为椎板交叉螺钉是一种易于采用、安全的固定方法，可以有效地恢复上颈椎的稳定性。 2.7 经关节突螺钉固定 1979年Magerl介绍了一种经关节突螺钉固定技术，是采用2枚螺钉，分别于两侧穿过C1-C2关节突进行固定。优点是可完限制旋转运动，缺点是技术性较强，潜在严重并发症，可能出现脊髓损伤、舌下神经损伤和椎动脉损伤等[20-23]。如果存在寰枢椎脱位，则需先进行复位才能采用此技术固定。为避免损伤，常规进行术前CT扫描以明确是否存在椎动脉走行变异。进钉点在C2下关节突内下角头侧3.0-4.0 mm和外侧3.0-4.0 mm处。螺钉方向是通过C2峡部和椎弓根复合体、穿过C1-C2关节、指向C1前结节。可以先置入导针穿过4层皮质：C2后侧入点、C2上关节面、C1下关节面、C1前侧皮质，随后用3.5或4 mm直径全螺纹皮质骨钉沿克氏针置入，长度为34-44 mm。Nagaria等[24]对37例类风湿性关节炎寰枢椎失稳患者进行后路经关节突螺钉固定融合，随访7年，目测类比评分获得> 50%的改善率，97%的患者获得骨性融合，认为经关节突螺钉固定技术是一项安全的技术，患者可获得明显的疼痛和脊髓功能改善，并获得很高的融合率。Kim等[25]对比了经关节突螺钉固定技术和C1侧块-C2椎弓根钉棒固定技术的临床治疗效果，发现在Frankel评分、ODI评分、疼痛评分、螺钉置入正确率、融合率、出血量等几个方面，两项技术没有明显差别，而经关节突螺钉固定技术在手术时间和X射线暴露时间方面要明显减少。 2.8 Olerud颈椎固定系统 Olerud系统由两部分组成，上部分由相互对应的两个钩子形成1个爪子，可以牢牢抓住寰椎后弓，下部分是1枚寰枢椎经关节突螺钉，上下两部分之间可以通过3.5 mm直径的杆相连，并可通过横连将左右侧固定相连接，这样就可以形成一套坚强的寰枢椎前后三柱固定系统。这套系统固定坚强，适合于C1后弓缺如的情况进行内固定[26-27]。Cornefjord等[28]采用Olerud系统治疗26例非肿瘤性寰枢椎失稳患者，平均随访15个月，没有神经或血管损伤等并发症，没有移位或再手术者，除6例患者因其他原因死亡外，其余20例患者均为影像学融合，认为Olerud系统进行上颈椎融合是安全有效的，不需要大骨块结构性植骨，且融合率是很高的。 2.9 寰椎侧块螺钉最早由Goel于1994年提出寰椎侧块螺钉固定技术，通过C1侧块螺钉、C2椎弓根螺钉和钢板连接固定，被称作Goel技术[29]。随后由Harms于2001年对此项技术进行了改进，采用C1侧块万向螺钉、C2椎弓根万向螺钉和棒进行连接固定，被称作Harms技术[30]。这种技术的优点是在置入内固定之前，不需要C1和C2之间达到解剖对位和对线，另外这种技术可以应用于椎动脉变异的病例。侧块螺钉的进钉点在C1侧块的中心或在C1侧块中点与C1后弓下面的连接点，距离中线在18 mm左右，进钉方向内倾15°，头倾15°，也可侧位透视，钻头瞄准C1前结节。侧块螺钉一般长度在22 mm左右，力学强度较高，但是显露范围较广，需要事先处理表面的静脉丛，可能会有大量出血，需要采用双极电凝和止血物质控制C2神经根和椎动脉周围的静脉丛出血，可能会损伤侧块外侧的椎动脉。Goel教授报道通过牺牲C2神经节来获得广泛的显露，一般不会引起明显的神经症状。将C2神经根切除或游离后，可显露出位于C1后弓之下的C1侧块，可用神经剥离器触探和明确C1侧块的内壁，做为螺钉的内侧界，辩明C1和C2的横突孔内侧壁，做为置入螺钉的外侧界[31-32]。 2.10 寰椎椎弓根螺钉固定[33-37] 由于C1侧块进钉点表面由一个大静脉丛覆盖，常常由于出血较多影响视野，止血又相当费时费力，因此为避免这个缺点，Resnick等[33-34]于2002年描述了C1椎弓根螺钉固定技术。由于寰椎解剖上的特殊性，缺乏椎体和椎板结构，因此不存在严格意义上的椎弓根，有学者将寰椎侧块视为椎体，后弓作为椎弓。所谓侧块螺钉和椎弓根螺钉的主要区别在于进钉点位置的不同和螺钉固定长度的不同。椎弓根螺钉的进钉点在中线外侧18-20 mm、后弓下缘上2 mm的交点，进钉方向与冠状面垂直、头倾5°。椎弓根螺钉长度一般在30 mm左右，力学强度更高，显露范围略小，不需要显露C2神经节，进钉点略偏内，有可能损伤后弓上缘的椎动脉沟内椎动脉[35]。Ma等[36]在12具成人新鲜尸体标本上测试对比了C1椎弓根螺钉和C1侧块螺钉拔出生物力学强度，发现双皮质C1椎弓根螺钉拔出力学强度最高，单皮质C1侧块螺钉拔出强度最低，单皮质C1椎弓根螺钉拔强度与双皮质C2侧块螺钉无明显区别。Fensky等[37]采用9个人颈椎标本采用C1侧块螺钉和C1椎弓根螺钉固定，进行疲劳稳定性测试，发现C1椎弓根螺钉固定强度远远大于C1侧块螺钉，认为C1椎弓根螺钉是非常有前景的一种内固定方式。 2.11 枢椎峡部螺钉固定枢椎峡部位于上、下关节面之间的狭窄部分，在横突孔的内后侧。C2峡部螺钉的骨道与C1-2经关节突螺钉类似，除了长度较短外。入钉点在C2下关节突内下侧角的头侧3 mm和外侧3 mm交界处。螺钉方向是沿较为陡峭的角度，平行于C2峡部，内倾角10°，大于关节突螺钉角度，头倾角40°，小于关节突螺钉角度。螺钉长度一般是16 mm，恰恰在横突孔处停止，往往需要在术前CT平扫时确认这一长度。C2峡部螺钉依然有损伤椎动脉的风险，但其风险要低于经关节突螺钉[38-39]。 2.12 枢椎椎弓根螺钉固定技术[40-48] Leconte[40]于1964年最早描述采用枢椎弓根螺钉治疗创伤性滑椎。20年后，Borne等[41]报道了18例枢椎创伤性滑椎患者安全地采用这项技术进行治疗并取得良好治疗效果，至此，这项技术才为人们所了解。 Roy-Camille等[42-43]于1989年和1991年2次报道应用这项技术治疗枢椎相关疾病后，随着颈椎侧块钢板技术的推广，这项技术逐渐获得广泛的临床应用。C2椎弓根是连接C2椎体与背侧结构的部分，是C2椎体向后外侧的骨性延伸，位于横突孔的前内侧、上关节面下方。由于C2峡部和椎弓根在解剖上的紧密关系，临床上称为“椎弓根峡部复合体”。C2椎弓根螺钉的骨道与C2峡部螺钉明显不同，关于C2椎弓根螺钉的进钉点和进钉方向多家学者有不同的论述[44]。Howington法进钉点在棘突正中线向外26 mm，下关节突下缘向上9 mm的交点，进钉方向内倾角35.2°，头倾角38.8°[45]；Xu法进钉点在C2椎板上缘向下5 mm，椎管内壁向外7 mm的交点处，进钉方向内倾角男性33.3°、女性32.7°，头倾角男性20.4°、女性20.0°[46]；Mummaneni法进钉点在C2下关节突内下角向上5 mm，向外1 mm处，方向内倾15-25°，头倾20°[47]；国内苗军等[48]提出区域法置钉技术，进钉区在枢椎下关节突内上象限，神经剥离器显露枢椎峡部上壁和内壁，根据上壁和内壁的走行方向决定进钉的内倾角和头倾角。"

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