脊柱导航手术机器人寰枢椎椎弓根的双置入方法

Dual atlantoaxial pedicle placement using spinal navigation surgery robot

背景:寰枢椎椎弓根内固定具有良好的生物力学效果,但因其椎弓根容积小、个体差异大,与脊髓、椎动脉及神经根等组织毗邻等原因使这一内固定技术的推广应用受到限制,寰枢椎椎弓根置入精度有待进一步提高。目的:探索自主研制的脊柱导航手术机器人进行寰枢椎椎弓根双置入的原理,以建立一种精度更高、更为安全且简便易行的新方法。方法:置入前在头尾侧等分椎弓根的寰枢椎CT剖面图像上,于正中矢状线两侧、椎骨后部弧形骨线上各选取一点,其联线构成一条横线;位于该横线与切过寰枢椎后部最远点的水平线间的正中矢状线构成一条竖线,这样就在寰枢椎椎骨上即体内设置了一条长度已知且相互垂直的横线与竖线。术中在双置入机器手两定位杆尖端间和线配准器上各设定一条相互垂直的横线和竖线,即体外横线和竖线,其长度分别与体内横线和竖线相等。通过X射线侧位透视,将体内和体外的横线与竖线配准,并使两定位杆的尖端紧压寰椎后弓骨面,从而确定寰枢椎椎骨的正中矢状面、冠状面及水平面。设定双置入机器手两导针中心轴线间的距离与左右两置入点间的距离相等,且其中心轴线与正中面的夹角与术前测量的椎弓根中心轴线与正中矢状线的夹角相等,实时动态监测下,脊柱导航手术机器人沿椎弓根中心轴线准确双侧置入。结果与结论:应用脊柱导航手术机器人行寰枢椎椎弓根双置入,当体内、外的横线及竖线配准及双置入机器手两定位杆的尖端紧密接触弧形骨面时,两导针的尖端只能落在左右椎弓根的置入点上。实时动态监测下,可保证沿寰枢椎左右椎弓根中心轴线准确双置入。

BACKGROUND： Atlantoaxial pedicle screw is thought to be the most stable instrumentation for reconstructive surgery of the cervical spine. However, because of the unresolved and inherent risk of neurovascular injuries due to screw perforation, it remains not widespread nowadays despite the excellent biomechanical property. The accuracy of atlantoaxial pedicle screw placement needs to be improved. OBJECTIVE： To explore the principle of spinal surgical navigation surgery robot atlantoaxial transpedicular dual placement with the aim of establishing a high accurate and easily operation atlantoaxial transpedicular dual placement technique. METHODS： Prior to surgery, on CT scanning image bisecting atlantoaxial pedicle in superior/inferior, each point was selected on both sides of sagittal line respectively, which located on vertebra arc-shaped epiphyseal line. The line segment across the above two points was named tranverse line （TL）. The midline cuts TL and the line tangent to the furthest point of at the back of atlantoaxial respectively, and the line segment across the two points was named perpendicular line （PL）, thus TL and PL which have known length and orthogonality were set on vertebra. Intraoperatively, one tranverse line and one perpendicular line with the same length to TL and PL respectively were set in vitro on dual placement manipulator. Under X-ray lateral fluoroscopy, the two tranverse lines and two perpendicular lines were matched respectively, the tip of manipulator＇s registration arm contact tightly the surface of vertebra, accordingly, atlantoaxial sagittal plane, coronal plane, horizontal plane were confirmed. The length between both guide-wires＇ tip was set equally to the length of both entry points, the angle between the centre axis line of pedicle and the midline equally to preoperative measurements, dual placement along the centre axis line of pedicle can be conducted with spinal navigation surgery robot with real-time monitoring. RESULTS AND CONCLUSION： With the application of spinal navigation surgery robot to dual placement on atlantoaxial vertebra, when inside and outside traverse line, perpendicular line were matched respectively, and the tip of manipulator＇s registration arm contact tightly arc-shaped surface of vertebra, the tips of both guide-wires locate nowhere but the entry points of both pedicles. With real-time monitoring, dual placement along the center axis line of pedicle can be performed with spinal naviclation surgery robot, which can provide accurate implantation of atlantoaxial placement.