寰椎“椎弓根”三维CT重建测量及分型的临床意义

目的:研究通过三维CT重建测量正常状态下寰椎"椎弓根"形态及其相关解剖学数据,对其进行分类并探讨其临床意义。方法:选取150例正常成人志愿者,年龄18～52岁(平均32.3岁),排除相关上颈椎疾患,尤其局部骨性增生明显者。对其寰枢椎进行螺旋CT扫描,在CT三维多平面重建下,取经枢椎下关节突中点矢状线延长线与寰椎椎动脉沟底部下2mm处后弓的交点为A点,同时建立通过椎动脉沟底部下2mm处的寰椎横切面图,取寰椎后弓移行为侧块处椎动脉孔内壁与椎管外壁连线的中点为B点,AB连线的延长线与寰椎前弓的交点为C点,AC连线即为寰椎椎弓根钉道。取经AC连线建立寰椎椎弓根通道的矢状面切图。测量寰椎双侧椎弓根各主要解剖参数:寰椎椎弓根的上倾角,椎动脉沟底椎弓根厚度(H1),寰椎椎弓根最大厚度;根据H1数值的大小分型,探讨各分型与椎弓根钉选择的相符性。结果:钉道椎动脉沟底处骨质厚度为4.10±1.17mm。根据H1数值的大小,以直径4.00mm和3.50mm的螺钉为参照,分为四型:正常型:H1>4.00mm(92例,61.3%);相对狭窄型:3.500.05)。正常型和相对狭窄型建议采用"椎弓根"螺钉技术。狭窄型和无椎弓根型者采用侧块螺钉技术。结论:三维CT重建能够准确提供寰椎椎弓根的解剖学形态、解剖学参数,根据寰椎椎动脉沟处骨质的高度进行分类,可以较好的指导寰椎后路"椎弓根"及侧块螺钉固定技术的选择及螺钉直径的选择。     

中上颈椎侧块与寰椎椎弓根位置关系的解剖研究

目的研究中上颈椎侧块与寰椎椎弓根的位置关系,建立以中上颈椎侧块为解剖标志的寰椎椎弓根螺钉进钉点定位技术。方法20具尸体标本,分别测量寰椎椎弓根和中上颈椎侧块的内缘、中点、外缘与正中矢状面的垂直距离,通过分析测量值间的关系,建立寰椎椎弓根螺钉进钉定位技术。结果C2-4侧块的内缘分别在寰椎椎弓根内缘外侧0．37mm、0．27mm、0．24mm处;C2-4侧块的中点分别在寰椎椎弓根中点外侧1．18mm、1．41mm、1．74mm处;C2-4侧块的外缘分别在寰椎椎弓根外缘外侧1．96mm、2．54mm、3．24mm处。结论中上颈椎侧块与寰椎椎弓根间存在较恒定的解剖位置关系,C3和C4侧块与枢椎侧块一样,可作为术中确定寰椎后弓显露范围和判断寰椎椎弓根螺钉进钉点的解剖学标志。     

寰椎椎弓根螺钉固定技术的改进研究

目的 探讨寰椎椎弓根螺钉的置钉方法. 方法 以电子游标卡尺测量48具干燥寰椎标本的相关解剖学数据;并依据寰椎椎弓根的形态对寰椎进行分类,提出了针对不同类型寰椎的各种椎弓根螺钉置钉方法. 结果 钉道处椎动脉沟底骨质厚度小于螺钉直径3.5mm的占16.7%(8/48),其中4.2%(2/48)厚度小于螺钉半径1.75mm.将寰椎分为普遍型(占83%)、轻度变异型(占13%)和重度变异型(占4%). 结论 对于寰椎后弓高度偏小的患者,可以部分经寰椎后弓或跨越寰椎后弓实现寰椎的椎弓根螺钉固定,进钉位置的确定应以术前三维CT重建和术中探查结合考虑.     

寰椎椎弓根螺钉进钉点的解剖定位研究

目的：建立简易可靠的寰椎后路椎弓根螺钉进钉点的定位技术。方法：设定寰椎椎弓根螺钉的进钉点，利用40套干燥配套寰枢椎标本，测量与进钉点相关的数据参数，分析数据之间的关系。结果：寰椎椎弓根螺钉进钉点和枢椎下关节突中线与后正中矢状面的距离分别是19.61mm、19．21mm，二者仅相差0．40mm。结论：枢椎下关节突中心点可作为术中判断寰椎椎弓根螺钉进钉点的解剖学定位标志。     

椎动脉的解剖研究及在上颈椎椎弓根置钉中的应用

目的：测量上颈椎椎弓根与椎动脉的位置关系,提高上颈椎椎弓根螺钉置入的安全性。方法：成人头颈部尸体标本6具（12侧）,解剖椎动脉,测量寰椎椎弓根螺钉进钉点处椎动脉下缘距椎动脉沟底部的距离,枢椎横突孔內缘与椎动脉內缘的距离,横突孔内椎动脉的外径,记录数据并进行统计学处理。结果：寰椎椎弓根螺钉进钉点处椎动脉下缘距椎动脉沟底部的距离为左侧（1.96±0.72）mm,右侧（1.99±0.61）mm,枢椎横突孔內缘与椎动脉外缘的距离为左侧（2.23±0.43）mm,右侧（2.30±0.39）mm,横突孔内椎动脉的外径为左侧（3.03±0.48）mm,右侧（2.98±0.75）mm。结论：除了椎动脉高跨病例外,正确置入上颈椎椎弓根螺钉无损伤椎动脉之虞,椎弓根钉置入时应尽量个体化。     

基于三维CT重建的寰椎椎弓根解剖学测量及临床意义

目的：研究螺旋CT三维重建测量人正常状态下寰椎椎弓根形态及其相关解剖学数据。方法：选取150例正常成人志愿者,年龄18—52岁（平均36．3岁）,对其寰枢椎进行螺旋CT扫描,三维重建后观察椎弓根形态,并测量其双侧椎弓根各主要解剖数值：椎弓根高度、宽度、进钉点距后正中矢状面距离、椎根弓内倾角及上倾角。结果：根据椎弓根高度分为正常型;相对狭窄型;狭窄型;无椎弓根型。正常寰椎椎弓高度（4．10±1．17）mm,上倾角（8．24±1．31）°,内倾角（6．53±2．35）°,椎弓根宽度（8．24±1．31）mm,长度（28．73±1．66）mm,进钉点距后正中矢状面距离（19．36±1．27）mm。结论：三维CT重建能够全面观察寰椎影像解剖的立体结构,准确提供寰椎椎弓根的解剖学形态、解剖学参数,为寰椎椎弓根螺钉内固定技术提供解剖学依据。     

后路寰椎侧块螺钉结合枢椎椎弓根螺钉固定治疗上颈椎不稳

目的：总结应用寰椎侧块螺钉与枢椎椎弓根螺钉技术固定融合治疗寰枢椎不稳的效果，探讨寰枢椎不稳的治疗方法。方法：采用寰椎侧块螺钉与枢椎椎弓根螺钉技术对15例寰枢椎不稳的患者进行了固定术，同时行自体髂骨融合。分别应用Vertex 7例，Axis 3例，和cervifix 5例，齿状突陈旧性骨折5例，新鲜Ⅱc型齿状突骨折6例，先天性游离齿状突4例。寰椎侧块螺钉进钉点选择在寰椎后结节中点旁开18mm～20mm，与后弓下缘以上2mm的交点，钉道方向在冠状面垂直，矢状面上螺钉头端向头侧倾斜约5°.枢椎进钉点为枢椎下关节突根部中点，钉道与矢状面夹角约15°，横断面夹角约30°。螺钉直径3．5mm，寰椎侧块螺钉长度28mm～32mm，枢椎椎弓根螺钉长度为22mm～26mm。结果：所有患者均未发生脊髓损伤和椎动脉损伤。随访10～25个月，平均14个月。术前JOA评分5．1～10．9分，平均7．6分。术后JOA评分13．2～16．8分，平均14．8分，改善率87．5％。植骨块全部融合，无内固定断裂、松动。结论：后路寰椎侧块螺钉与枢椎椎弓根螺钉技术稳定性良好，具有三维固定的优点，值得推广。     

寰椎后弓变异患者寰椎椎弓根螺钉的置钉策略

目的:探讨寰椎后弓变异患者寰椎椎弓根螺钉的置钉方法及其安全性.方法:回顾性分析2005年1月～2011年1月寰椎后弓变异行寰椎椎弓根螺钉固定的28例患者,其中男11例,女17例;年龄6～75岁,平均36.2±15.5岁.根据CT重建图像将寰椎椎弓根划分为后弓表面、椎动脉沟底和椎弓根侧块交界区3个切面,并将每个切面再分为内侧、外侧2个部分.对各部位相应切面的后弓高度进行测量,根据所测结果,将变异寰椎后弓分为3种类型,并采用相应的椎弓根螺钉置钉方法:Ⅰ型(寰椎后弓表面高度＜3.5mm,椎动脉沟底椎弓根高度＞3.5mm),采取后弓下置钉;Ⅱ型(后弓表面高度及椎动脉沟底椎弓根高度均＜3.5mm),采取椎弓根侧块交界点处置钉;Ⅲ型(后弓表面高度＞3.5mm,椎动脉沟底椎弓根高度＜3.5mm),采取in-out-in技术置钉.术后采用CT片评价置钉准确性,并观察并发症发生情况.结果:56个寰椎后弓变异的椎弓根中,Ⅰ型34个,Ⅱ型18个,Ⅲ型4个.术中成功置钉54枚,成功率96.4％;2个Ⅱ型变异后弓椎弓根(2例一侧)因椎弓根过小无法置钉而改用椎板钩固定.术后CT显示理想和可接受置钉52枚(96.3％);不可接受置钉2枚(3.7％),均表现为螺钉穿入椎管.2例患者术后出现枕大神经刺激症状,1例经对症处理、1例拆除内固定后症状缓解.术中与术后均未发生大出血,无椎动脉、神经根及脊髓损伤,无寰椎后弓骨折等其他并发症.结论:寰椎后弓变异患者仍可采用寰椎椎弓根螺钉固定,在实施时应根据不同分型采用相应的置钉策略.     

枢椎椎弓峡部引导下寰椎椎弓根置钉的CT测量及其应用

目的:探讨在枢椎椎弓峡部引导下实施寰椎椎弓根螺钉置钉的可行性及安全性。方法:对48例成人寰枢椎行三维CT重建,取枢椎椎弓峡部内上缘与寰椎的横断面图像。测量椎管正中线至寰椎椎弓根内壁、外壁及枢椎椎弓峡部内壁、外壁的距离,分别为L1、D1、L2、D2;0°内倾角置钉时,以枢椎椎弓峡部内上壁为解剖标志,确立最内侧进钉点A和最外侧进钉点B,减去螺钉半径1.75mm,A、B点至枢椎椎弓峡部内上壁的距离分别为(L1-L2+1.75mm)、(D1-L2-1.75mm),寰椎后弓上置钉时螺钉允许的最大内倾角与最大外倾角大致相等时的点为最佳进钉点(M点),记录M点至枢椎椎弓峡部内上壁水平间距。自2004年3月～2009年3月对29例患者采用以枢椎椎弓峡部为标志实施后路寰枢椎椎弓根螺钉内固定手术,其中陈旧性齿状突骨折24例,横韧带损伤并寰椎前脱位5例。观察手术过程中与寰椎椎弓根螺钉置钉相关的并发症,术后三维CT重建观察螺钉的位置。结果:0°内倾角置钉时,CT测量最内侧进钉点A、最外侧进钉点B、最佳进钉点M至枢椎椎弓根峡部内上壁的水平间距分别为4.22±0.54mm、8.66±0.73mm、5.79±0.63mm。临床共置入寰椎椎弓根螺钉58枚,术中枢椎椎弓峡部内上壁均得到良好显露,未出现椎动脉、静脉丛损伤出血及脊髓、C2神经根损伤等并发症。术后三维CT复查显示所有寰椎椎弓根螺钉均未误入椎管或椎动脉孔,测量寰椎椎弓根螺钉进钉点与枢椎椎弓峡部内上壁水平间距为5.45±0.82mm,与术前M点测量值相比较无显著性差异。结论:在纠正寰椎旋转移位后,以枢椎椎弓峡部内上壁作为解剖参照,寰椎椎弓根存在一定的置钉安全区间,利用该解剖标志行寰椎椎弓根置钉是安全可行的。     

多平面CT重建下个体化改良寰椎椎弓根进钉路径的测量

目的:通过对寰椎椎弓根轴位、矢状位多平面CT重建,测量个体化改良椎弓根进钉路径数据,以期提高寰椎椎弓根置钉准确率。方法:20具成人颈椎标本,男11具,女9具,年龄不详。进行螺旋CT薄层扫描多平面重建,在寰椎椎弓根轴位像上建立改良的椎弓根进钉路径,即经椎管外缘和齿突孔外缘划切线L1线,经椎动脉孔内缘画L2线平行于L1线,经L1、L2线之间中点画A线平行于L1、L2线,A线即为改良的寰椎椎弓根进钉路径。根据A线确定并测量椎弓根进钉点、进钉方向等个体化置钉参数,根据测量的置钉参数在标本的寰椎椎弓根置入直径3.5mm皮质骨螺钉。置钉后行螺旋CT扫描,按Ludwing椎弓根置钉安全标准统计椎弓根螺钉误置率。结果:多平面CT重建后影像学测量表明,改良寰椎椎弓根进钉路径的进钉点距寰椎后结节:右侧25.8±1.9mm,左侧25.7±1.8mm,比传统的进钉点(距寰椎后结节18~20mm)更偏外;进钉内倾角度:右侧21.1°±4.6°,左侧20.0°±4.9°,比传统的内倾角(0~10°)更大。20具颈椎标本共置钉40枚,按照Ludwing椎弓根置钉安全标准:0级36枚(90%),1级4枚(10%)。结论:寰椎椎弓根多平面CT重建下建立的改良椎弓根进钉路径,能够获取进钉点、进钉角度的个体化置钉参数。该路径比传统的方法进钉点更偏外,内倾角更大,能够提高寰椎椎弓根置钉准确率。     

经后路寰椎椎弓根螺钉固定的置钉研究

目的探讨经后路寰椎椎弓根螺钉固定的可行性. 方法利用20具颈椎尸体标本,模拟经后路寰椎椎弓根螺钉固定.在寰椎后弓后缘表面,经枢椎下关节突中心点纵垂线与寰椎后弓上缘下方3 mm水平线的交点作为进钉点,按内斜10度、上斜5度钻孔,经寰椎椎弓根置入直径3.5 mm的皮质骨螺钉.测量进钉点与寰椎椎弓根中线平面的距离、螺钉最大进钉深度、螺钉内斜角度和螺钉上斜角度等解剖指标,观察螺钉是否突破椎弓根和侧块骨皮质,以及椎动脉、硬膜、脊髓是否损伤等. 结果共放置40枚寰椎椎弓根螺钉,测得进钉点与寰椎椎弓根中线的平均距离为(2.20±0.42) mm,螺钉最大进钉深度平均(30.51±1.59) mm,螺钉内斜角度平均(9.70±0.67)度,上斜角(4.60±0.59)度.其中1枚螺钉因上斜角度过大穿破椎弓根上缘,8枚因后弓高度过小而突破椎弓根下缘,5枚进钉过深突破寰椎侧块前缘皮质,但均未对脊髓和椎动脉造成损伤. 结论经后路行寰椎椎弓根螺钉固定是安全可行的,但应注意进钉角度和深度.     

The anatomical study of transoral atlantoaxial reduction plate internal fixation

Irreducibleanterioratlantoaxialdislocationwithventralspinalcordcompressionpresentsadifficultsurgicalchallenge.Nowasagenerallyacceptedoptionforthiscondition,decompressionthroughtransoralapproachhastobefollowedby anotheroperationwithinstrumentationandfusionofthe uppercervicalspinetoachievesegmentalstability.HarmsandKandziora1havedescribeddirectinternal platefixationsthroughtransoralapproach,buttheplate adoptedbyHarmsdidnothavealockingmechanism andtheplateusedbyKandziorafailedtoachieve immediate…     

Anatomic and radiological study on posterior pedicle screw fixation in the atlantoaxial vertebrae of children

Objective： To investigate the feasibility of posterior fixation with 3.5-mm pedicle screws in the atlantoaxial vertebrae of children.
Methods： In this study, atlantoaxial vertebrae specimens were obtained from 10 cadavers of children aged 6-8 years. We measured the height and width of the C1 pedicle and the midportion of C1 lateral mass; the width of C1 posterior arch under the vertebral artery groove and the height of the external and internal one-third of this part; the external, internal height and the superior, middle, inferior width of the C2 pedicle （transverse foramen）. Furthermore, computed tomography （CT） axial scan was performed on 20 agematched volunteers to obtain relative data of their atlantoaxial vertebrae. We measured the length and width of the C1 and C2 pedicles in the atlantoaxial cross-sectional plane. On CT workstation, we also measured the angles between the longitudinal axes of the atlantoaxial pedicles and the midsagittal plane.
Results： For the cadaveric specimen group, the height and width of the C1 pedicle were （5.26±0.44） mm and （6.26±0.75） mm respectively. The height of the medial one-third of the Ct posterior arch under the vertebral artery groove was （4.07±0.24） mm. The external, internal height and superior, middle, inferior width of the C2 pedicle was （6.86±0.48） mm, （6.67±0.49） mm, （6.63 ±0.61） mm, （5.41±0.39） mm and （3.71±0.30） mm, respectively. For the volunteer group measured by CT scan, the height and width of the C1 pedicle were （5.47 ±0.34） mm and （6.63±0.54） mm respectively, while （6.59±0.51） mm and （5.13 ±0.42） mm of the C2 pedicle. The angles between the atlas, axis pedicles and the midsagittal plane were （9.60±1.32）° and （27.80±2.22）° respectively.
Conclusion： It is feasible to place a 3.5-mm pedicle screw in the C1 and C2 pedicles of children aged 6-8 years old.     

Anatomic study of the axis for surgical planning of transarticular screw fixation

Transarticular screw fixation has shown increased stability compared with other posterior stabilization techniques. However, there have been few reports on vertebral artery injury related to the screw insertion. The current study measured the parameters of the pedicle and vertebral artery groove of the axis and clarified the accuracy and safety of the transarticular screw fixation. Direct measurements were taken from 98 dry axis vertebrae. The width and height of the pedicle were measured. The mediolateral and anteroposterior dimensions of the vertebral artery groove also were measured. Forty-one percent had asymmetry. In 20% of the specimens, the pedicle was smaller than the diameter of the screw (3.5 mm). The pedicle of the axis has large anatomic variability and asymmetry. Some pedicles were not suitable for atlantoaxial transarticular screw fixation. The risks associated with screw fixation should be prevented by preoperative computed tomography with three-dimensional reconstruction. Screw trajectory reconstruction with coronal and sagittal reconstruction is useful to evaluate the pedicle width and height.     

经口咽前路寰枢椎复位钢板内固定的外科解剖学研究

目的为经口咽前路寰枢椎复位钢板内固定设计和应用提供解剖学依据。方法对10例新鲜的头颈部标本使用经口咽前入路进行逐层的显微外科解剖,观察咽后壁的层次、椎动脉的走行、寰枢椎的解剖毗邻关系和寰枢椎前路钢板内固定的相关解剖参数等。结果(1)咽后壁分两层和两个间隙粘膜层、椎前筋膜层,咽后间隙和椎前间隙;(2)经此入路可显露从枕骨大孔前缘至C3椎体的范围;(3)寰椎和枢椎椎动脉距中线的距离分别为寰椎(252±23)mm和枢椎(184±26)mm;(4)寰椎和枢椎可显露宽度分别为(394±22)mm和(390±21)mm,寰椎进钉点(侧块中点)间距(a)为(314±33)mm,寰椎进钉点连线与枢椎进钉点(枢椎前表面中部上关节面内缘连线与前唇下缘线之间的等距离线位于矢状中线两侧旁开3～4mm的位置)连线的垂直间距(b)为(187±27)mm,a/b比值为15～17。结论经口咽前入路行寰枢椎前路钢板内固定可行,钢板的设计应以上述测量数据为依据。     

Value of intraoperative true lateral radiograph of C2 pedicle for C1-2 transarticular screw insertion.

BACKGROUND CONTEXT: Transarticular C1-2 screws are widely used in posterior cervical spine instrumentation. Injury to the vertebral artery during insertion of transarticular Cl-2 screw remains a serious complication. Use of a computer-assisted surgery system decreases this complication considerably. However, this system encounters problems in ensuring complete accuracy because of positional variations during preoperative and intraoperative imaging generation. Therefore, intraoperative fluoroscopy still is one of the commonly used methods to guide insertion of transarticular Cl-2 screw. Evaluation of a true lateral radiographic view of the C2 pedicle for screw trajectory during C1-2 transarticular screw insertion may help to minimize this potential complication. PURPOSE: To evaluate the value of intraoperative true lateral radiograph of the C2 pedicle for screw trajectory during C1-2 transarticular screw insertion. STUDY DESIGN: To compare the height of the C2 pedicle area allowing instrumentation on true lateral view radiograph of the C2 pedicle and computed tomographic (CT) scan with multiplanar reconstruction. METHODS: Twenty embalmed human cadaveric cervical spine specimens were used to insert a total of 40 C1-2 transarticular screws using Magerl and Seemann technique. One side of the C2 transverse foramen was filled with radiopaque material (lead oxide) to simulate the artery and to demarcate the danger zone for better visualization on radiography. Measurements and calculation of the mean and standard deviation of the height of the area allowing instrumentation of the C2 pedicle were done on true lateral view radiograph of the C2 pedicle, the sagittal and 30 degrees sagittal views relative to the frontal plane passing exactly through the center of the C2 pedicle of CT scans. Student t test was applied to calculate the statistical significance of measured values. Statistical significance was defined as por=.36. Using sagittal CT scan views, the height of pedicles was 7.71+/-0.7 mm (right) and 7.58+/-1.01 mm (left), p>or=.23. On 30 degrees sagittal CT scan views, the height of pedicles was 7.84+/-1.00 mm (right) and 7.76+/-1.02 mm (left), p>or=.27. The p value was >or=.78, >or=.56, and >or=.49 for true lateral radiographic view and sagittal CT scan view, true lateral radiographic view and 30 degrees sagittal CT scan view, and sagittal CT scan view and 30 degrees sagittal CT scan views, respectively. On lateral view of cervical spine, the decline angle of the transarticular screw was 51.3+/-0.50 degrees (right) and 50.68+/-0.41 degrees (left), p>or=.17. Mean decline angle was 51+/-0.43 degrees . On the anteroposterior (AP) view, radiograph median angle was 6.87+/-0.53 degrees (right) and 6.0+/-0.59 degrees (left), p>or=.25. Mean median angle was 6.44+/-0.62 degrees. CONCLUSIONS: True lateral radiographic views of the pedicles provide useful information for defining screw trajectory intraoperatively. Using this view along with AP and lateral view of cervical spine and preoperative three-dimensional CT scan may narrow the margin of error in this delicate area.