1. Technical introduction
Since 1978, when Japanese scholar Hirabayashi et al. carried out posterior cervical vertebrae single-door cervical spinal canal enlargement plasty, the surgical method has been continuously improved, and it is now recognized as one of the most effective methods for the treatment of developmental cervical spinal stenosis, ossification of the posterior longitudinal ligament of the cervical spine and multilevel cervical myelopathy.
In single-door cervical laminoplasty, one side of the vertebral plate is completely cut off as the opening side, and the other side of the lamina is slotted as the hinge side, and the lamina is fixed and maintained by a certain method after the lamina is opened. There are many ways to maintain the door opening, the traditional method is the joint capsule suspension method, which fixes the vertebral plate suspension to the joint capsule on the hinge side through sutures, so as to stabilize the vertebral plate after opening the door, but some patients will have the phenomenon of reclosing the door and stubborn cervical axial symptoms after surgery.
The "anchoring method" is one of the modified procedures, which was first reported by Korean scholars Wang et al., through single-door spinal canal plasty combined with internal fixation of side block screws, and the sutures are fixed on the screws to strengthen the suspension effect, although this method can avoid the phenomenon of re-closing, but the loss of cervical flexion can occur, and there is a high incidence of axial symptoms. Artificial lamina reconstruction technology is to place the artificial lamina made of hydroxyapatite between the open vertebral plate and the side block to reconstruct the lamina structure, prevent the door from closing again, and have the advantages of reducing the formation of epidural scarring, this method is more popular in Japan and other regions, but it is rarely used in China.
The micro titanium plate fixation technology was first reported by O'Brien et al. in 1996, the technology forms a stable bridge structure between the raised vertebral plate and the ipsilateral side block through the micro titanium plate and screws, and forms a real rigid support for the door opening side, which can obtain instant stability, can effectively reduce or even avoid the occurrence of re-closing phenomenon, has the advantages of small cervical curvature loss, low incidence of axial symptoms, etc., and can be combined with artificial vertebral plates. A routine procedure for laminoplasty.
2. Anatomical measurements and data
The cervical spine measurement indexes and results are shown in Figure 1A, Figure 1B and Table 1~Table 3.
(1) Thickness of the lateral block (D1) ;(2) Tilt angle of the lateral block head (α): the angle between the upper facet articular surface and the cross-section of the vertebral body;(3) Thickness of the lamina (D2): the thickness of the narrowest part of the middle of the lamina.
Fig.1A Schematic diagram of lateral plane measurement of the middle and lower cervical vertebrae, side block thickness (D1), lateral block head inclination (α)
Fig. 1B Schematic diagram of cross-sectional measurement of lower cervical vertebrae, side block thickness (D1), lamina thickness (D2)
Table 1 Thickness of lateral blocks in the middle and lower cervical vertebrae
Table 2 Lateral lump inclination angle of the middle and lower cervical vertebrae
Table 3 Thickness of the middle and lower cervical vertebrae
3. Clinical significance
(1) Nail point
1. Side block end screws
The nail point is usually located in the middle and upper part of the back surface of the side block, and the back surface of the side block is divided into 4 equal parts from top to bottom, then the upper 1/2 is the absolute safety area, the middle and lower 1/4 is the relative safety area, and the bottom 1/4 is the danger area, except for the short screws of about 6mm, it is generally not suitable to place the nail (Fig. 2).
Fig.2. Schematic diagram of the nail insertion area of the end screw of the side block
2. Verebral end screws
The needle insertion point is located at the midpoint of the upper and lower lamina on the side of the door opening.
(2) Nail angle
1. Side block end screws
In the absolute safety area, it can be placed vertically or slightly outside and upward, and below the absolute safety area, it needs to be tilted 10°~40° to the cephalic end and 10°~25° to the outside to increase safety and avoid protruding into the lower articular surface or injuring the vertebral artery and nerve root.
2. Verebral end screws
It can be placed vertically or obliquely towards the spinous process.
(3) Nail depth
1. The thickness of the cervical lateral block C7 is the thinnest, which is 6.3~11.9mm, and C3 is the thickest, which is 8.2~13.7mm. Therefore, the length of the side block fixing screw is generally 6mm or 8mm.
2. The thickness of the cervical vertebral plate is 1.7~8.8mm, considering the existence of the subvertebral space after opening the door and the influence of the thickness of the titanium plate itself, the length of the fixing screw for inserting the vertebral plate is generally 6mm.
(4) Screw diameter
The diameter of the fixing screws at the end of the side block and the end of the lamina is usually 2.0 mm, but a 2.4 mm diameter screw can also be used as a rescue screw (Fig. 2-9-3).
Nail entry point: The nail entry point of the side block end screw is usually located in the middle and upper part of the rear surface of the side block, and try to avoid the distal end of the side block. The end screw insertion point of the lamina is located at the midpoint of the upper and lower vertebral plates on the side of the door.
Nail angle: the nail insertion point of the end screw of the side block is in the 1/2 area of the side block, which can be vertically inserted, and in the 1/2 area of the side block, it is necessary to tilt 10°~40° to the head end and 10°~25° to the outward side of the nail. The terminal laminamine screw is inserted vertically or obliquely toward the spinous process.
Fig.3. Schematic diagram of side block end screws and vertebral plate end screws (cross-sectional perspective view)
Nail depth: The length of the side block end screw is generally 6mm or 8mm. The length of the lamina end screw is 6mm.
Screw Diameter: The screw diameter is usually 2.0mm, and the 2.4mm screw can be used as a rescue screw.
4. Imaging standards
The miniature titanium plate is fixed between the lateral block of the cervical vertebra and the lamina, and there is no obvious displacement. The anteroposterior screw of the end screw of the lateral block is angled outward in the center area of the lateral block, and the lateral screw is angulated cephalad, and the screw does not invade the articular surface, vertebral artery foramen and spinal canal wall, and the end screw of the vertebral plate is placed vertically or outwardly in the vertebral plate of the side of the door opening (Fig. 4 A~C).
Fig.4 A: Anteroposterior X-ray after cervical single-door miniature titanium plate fixation, B: X-ray lateral X-ray after cervical single-door miniature titanium plate fixation, C: CT cross-section after cervical single-door miniature titanium plate fixation
bibliography
[1] Yang Mingkun, Liu Luoyi, Jia Xindong, Du Tao, Wu Dengpu, Zhang Xu.Clinical efficacy of posterior cervical vertebral single-door spinal canal enlargement lamineplasty in the treatment of cervical myelopathy complicated with cervicogenic headache[J].Journal of Spine Surgery,2024,22(01):1-4.
[2] Wang Lili, Li Chungen, Liu Genzhe, Zhao Ziyi, Zhao Sihao, Chen Chao, Zhu Yonggang, Li Wei.Clinical efficacy analysis of anterior cervical hybrid surgery and posterior cervical single-door spinal canal enlargement plasty in the treatment of multilevel cervical myelopathy[J].Journal of Jilin University(Medical Science),2024,50(01):228-235.
[3] Ge Xufeng, Chen Danhua, Ma Fengfeng.Effect of posterior cervical single-door spinal canalplasty combined with nerve root canal enlargement in the treatment of cervical myelopathy[J].Da Doctor,2023,8(23):1-4.
[4] Chen Longjun, Xue Wenyuan, Wang Junjiang, Liu Zhenhui, Liu Guanyan, Zhang Ming.Risk factors for sagittal plane imbalance after posterior single-door and double-door spinal canal enlargement plasty: a multicenter study[J].Journal of Neck and Low Back Pain,2023,44(06):1016-1020.
[5] Wang Li, Li Chungen, Yin Xincheng, Qi Yingna, Zhao Sihao, Li Wei, Tang Haojie.Effect of posterior cervical single-door spinal canal enlargement plasty on the sagittal balance of the cervical spine after surgery[J].Journal of Jilin University(Medical Science),2023,49(05):1318-1324.
[6] Wang Jinlu, Mei Wei, Wang Xiangshan, Zhang Hua, Yin Tielin, Shi Hailong.Long-term efficacy of posterior cervical vertebral single-door spinal canal enlargement plasty in the treatment of multi-level cervical spinal stenosis[J].Shenzhen Journal of Integrated Traditional and Western Medicine,2023,33(17):14-18.
[7] Wang Zhijin, Li Jingkun, Han Wenzhe, Wang Ziyi, Zou Debo.Comparison of two posterior decompression techniques in the treatment of cervical myelopathy[J].Chinese Journal of Orthopedics,2023,31(17):1549-1554.
[8] Xu Hongming, Li Fangcai, Wang Xiangyang, eds., Anatomy of Spinal Internal Fixation, 2019, People's Medical Publishing House
[9] Boqvist (ed.Orthopedic Fixation and Prosthetic Imaging), 2010, People's Medical Publishing House
[10] Practical Orthopaedics (2nd Edition), 2016, People's Medical Publishing House
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