Jackson David M, Karp Jacqueline E, O'Brien Joseph R, Anderson D Greg, Gelb Daniel E, Ludwig Steven C
Department of Orthopaedics, University of Maryland, Baltimore, MD.
Department of Orthopaedic Surgery, George Washington University Hospital, Washington, DC.
Int J Spine Surg. 2012 Dec 1;6:62-70. doi: 10.1016/j.ijsp.2011.12.003. eCollection 2012.
We describe a technique for percutaneous transfacet screw placement in the cervical spine without the need for lateral-view fluoroscopy.
Previously established articular pillar morphometry was used to define the ideal trajectory for transfacet screw placement in the subaxial cervical spine. A unique targeting guide was developed to allow placement of Kirschner wires across the facet joint at 90° without the guidance of lateral-view fluoroscopy. Kirschner wires and cannulated screws were placed percutaneously in 7 cadaveric specimens. Placement of instrumentation was performed entirely under modified anteroposterior-view fluoroscopy. All specimens were assessed for acceptable screw placement by 2 fellowship-trained orthopaedic spine surgeons using computed tomography. Open dissection was used to confirm radiographic interpretation. Acceptable placement was defined as a screw crossing the facet joint, achieving purchase in the inferior and superior articular processes, and not violating critical structures. Malposition was defined as a violation of the transverse foramen, spinal canal, or nerve root or inadequate fixation.
A total of 48 screws were placed. Placement of 45 screws was acceptable. The 3 instances of screw malposition included a facet fracture, a facet distraction, and a C6-7 screw contacting the C7 nerve root in a specimen with a small C7 superior articular process.
Our data show that with the appropriate radiographic technique and a targeting guide, percutaneous transfacet screws can be safely placed at C3-7 without the need for lateral-view fluoroscopy during the targeting phase. Because of the variable morphometry of the C7 lateral mass, however, care must be taken when placing a transfacet screw at C6-7.
This study describes a technique that has the potential to provide a less invasive strategy for posterior instrumentation of the cervical spine. Further investigation is needed before this technique can be applied clinically.
我们描述了一种无需侧位透视荧光镜检查即可在颈椎中经皮放置经关节突螺钉的技术。
利用先前确定的关节突形态测量法来确定下颈椎经关节突螺钉置入的理想轨迹。开发了一种独特的瞄准导向器，以允许在无侧位透视荧光镜检查引导的情况下将克氏针以90°穿过关节突关节。在7个尸体标本中经皮放置克氏针和空心螺钉。器械置入完全在改良前后位透视荧光镜检查下进行。由2名接受过专科培训的骨科脊柱外科医生使用计算机断层扫描对所有标本的螺钉置入情况进行评估，以确定是否可接受。通过开放解剖来确认影像学解释。可接受的置入定义为螺钉穿过关节突关节，在下关节突和上关节突获得锚定，且不侵犯关键结构。位置不当定义为侵犯横突孔、椎管或神经根或固定不充分。
共置入48枚螺钉。45枚螺钉的置入是可接受的。3例螺钉位置不当的情况包括1例关节突骨折、1例关节突分离，以及在1例C7上关节突较小的标本中1枚C6 - 7螺钉接触C7神经根。
我们的数据表明，采用适当的影像学技术和瞄准导向器，在靶向阶段无需侧位透视荧光镜检查即可安全地在C3 - 7置入经皮经关节突螺钉。然而，由于C7侧块形态测量的变异性，在C6 - 7置入经关节突螺钉时必须小心。
本研究描述了一种有可能为颈椎后路器械置入提供侵入性较小策略的技术。在该技术能够应用于临床之前，还需要进一步研究。
