寰椎“椎弓根”三维CT重建测量及分型的临床意义

Clinical significance of measurements and classification of atlas pedicles by three-dimensional computer tomography and reconstruction

中文关键词:  寰椎  椎弓根  形态分类  解剖学  三维CT重建

英文关键词:Atlas  Pedicle  Morphological classification  Anatomy  3D-CT reconstruction

中文摘要:

  【摘要】 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：3.50＜H1≤4.00mm（33例，22%）；狭窄型：3.00＜H1≤3.50mm（15例，10%）；无椎弓根型：H1≤3.00mm（10例，6.7%）。正常寰椎椎弓高度4.10±1.17mm，上倾角8.24°±1.31°。左右两侧比较无差异（P＞０．０５）。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。

英文摘要:

  【Abstract】 Objectives: To investigate the anatomic morphology and measurements and the clinical significance of C1 pedicles by 3D-CT reconstruction． Methods: Normal C1-2 of 150 adults from 18 to 52 years old (averaged, 32.3 years old) were scanned by 3D-CT reconstruction. The cases with upper cervical spine diseases, especially visioned osteophyte were excluded. After reconstruction, the transverse sections were established by going through the points 2 mm below the vertebral artery sulcus． Point A was the intersection point of production of sagittal median line going through the central point of C2 inferior facet process and posterior arch at the transverse section． Point B was the middle point of line connecting of the inner wall of vertebral artery foramen and the external wall of spinal canal. Point C was the intersection point of extended line of line connecting of A and B and the anterior arch of axis. The line connecting A and C was the pedicle screw trajectory in C1. The sagittal sections were established by going through the line connecting A and C. To measure the anatomic measurements of both sides of C1 pedicles： the thickness and width of vertebral artery sulcus(H1), orientation of pedicles, and the maximum thickness of C1 pedicles. According to the value of H 1, the consistency of the classification of C1 pedicles and determination of the posterior screw placement were evaluated. Results: The value of H1 decided the posterior pedicle screw instrumentation. According to the value of H1 and the standard diameter for screw of 3.50 mm and 1.75 mm, the anatomic morphology of C1 pedicles were classified into four types: general: H1＞4.00mm（92 cases，61.3%）; slightly narrow: 3.50＜H1≤4.00mm（33 cases, 22%）, narrow: 3.00＜H1≤3.50mm（15cases，10%） and no pedicle: H1≤3.00mm（10 cases，6.7%）(6.7%). For normal atlas, the height of pedicles was　4.10±1.17mm, the orientation of pedicles was 8.24°±1.31°　caudally. There was no side-related difference. Pedicle screw fixation was indicated for general and slightly narrow type, while lateral mass screw was indicated for the narrow and no pedicle type. Conclusions: The anatomic measurements of C1 pedicles can be determined by 3D-CT reconstruction. This classification based on the thickness of vertebral artery sulcus is feasible and can guide the selection of internal fixations.