Kaito Takashi, Matsukawa Keitaro, Abe Yuichiro, Fiechter Meinrad, Zhu Xia, Fantigrossi Alfonso
Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Japan.
Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Japan.
J Orthop Sci. 2018 Nov;23(6):865-869. doi: 10.1016/j.jos.2018.06.005. Epub 2018 Jul 2.
Cortical pedicle screw placement is an attractive technique in terms of both fixation strength and less invasiveness. However, to insert the screw with penetrating cortical bone on the ideal trajectory is technically demanding. The use of three-dimensional (3D) patient-matched guides may facilitate the use of this technique.
To examine the accuracy of cortical screw placement using a patient-matched targeting guide with a cadaveric study assessing the accuracy.
The 3D planning of the pedicle screw placement, including the location at which the screw would pass through the center of the pedicle, sagittal/transverse trajectory (angle), length, and diameter, was developed using 3D CAD design software. Three-dimensional guides based on the preoperative planning were created for three cadaveric specimens (L1 to S1, 36 pedicles). Screws (n = 18) and pins (n = 18) were placed using K-wire or drill-based guides, without X-ray exposure. Actual positioning was compared to the preoperative plan by superimposing the inserted screws/pins based on postoperative CT. The placement accuracy was graded based on the degree of perforation of the pedicle by the pedicle screw or pin using an acceptance criterion (no perforation; Grade A, 0-2 mm; Grade B, 2-4 mm; and Grade C, >4 mm). The mean deviation between the planned and inserted screw positions on the coronal plane at the midpoint of the pedicle was compared to the accuracy of screw guide for traditional pedicle screw trajectory (0.70 mm).
Of 35 evaluated screws and pins, 32 (91.4%) were inserted completely inside the pedicle. All pedicle perforation was within 2 mm. The mean deviation from the plan at the midpoint of pedicle was 0.66 mm; thus, the accuracy was within the predefined criteria.
Cortical pedicle screw placement using 3D-patient matched guides is accurate. Further clinical studies are required to confirm the radiographic and clinical effects.
皮质椎弓根螺钉置入术在固定强度和微创性方面都是一种有吸引力的技术。然而，要在理想轨迹上穿透皮质骨插入螺钉在技术上要求很高。使用三维（3D）患者匹配导向器可能会促进该技术的应用。
通过尸体研究评估使用患者匹配靶向导向器进行皮质螺钉置入的准确性。
使用3D CAD设计软件进行椎弓根螺钉置入的三维规划，包括螺钉穿过椎弓根中心的位置、矢状/横向轨迹（角度）、长度和直径。根据术前规划为三个尸体标本（L1至S1，36个椎弓根）制作三维导向器。使用克氏针或基于钻头的导向器放置螺钉（n = 18）和销钉（n = 18），无需X线暴露。术后通过CT将插入的螺钉/销钉进行叠加，将实际定位与术前规划进行比较。根据椎弓根螺钉或销钉对椎弓根的穿孔程度，使用验收标准（无穿孔；A级，0 - 2毫米；B级，2 - 4毫米；C级，>4毫米）对放置准确性进行分级。将椎弓根中点冠状面上计划和插入螺钉位置之间的平均偏差与传统椎弓根螺钉轨迹的螺钉导向器准确性（0.70毫米）进行比较。
在35枚评估的螺钉和销钉中，32枚（91.4%）完全插入椎弓根内。所有椎弓根穿孔均在2毫米以内。椎弓根中点处与计划的平均偏差为0.66毫米；因此，准确性在预定义标准范围内。
使用3D患者匹配导向器进行皮质椎弓根螺钉置入是准确的。需要进一步的临床研究来证实其影像学和临床效果。
