Takemoto Mitsuru, Fujibayashi Shunsuke, Ota Eigo, Otsuki Bungo, Kimura Hiroaki, Sakamoto Takeshi, Kawai Toshiyuki, Futami Tohru, Sasaki Kiyoyuki, Matsushita Tomiharu, Nakamura Takashi, Neo Masashi, Matsuda Shuich
Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, Kyoto, 606-8507, Japan.
Department of Orthopaedic Surgery, Shiga Medical Center for Children, 5-7-30, Moriyama, Shiga, 524-0022, Japan.
Eur Spine J. 2016 Jun;25(6):1698-705. doi: 10.1007/s00586-015-3908-z. Epub 2015 Mar 29.
Image-based navigational patient-specific templates (PSTs) for pedicle screw (PS) placement have been described. With recent advances in three-dimensional computer-aided designs and additive manufacturing technology, various PST designs have been reported, although the template designs were not optimized. We have developed a novel PST design that reduces the contact area without sacrificing stability. It avoids susceptibility to intervening soft tissue, template geometric inaccuracy, and difficulty during template fitting.
Fourteen candidate locations on the posterior aspect of the vertebra were evaluated. Among them, locations that had high reproducibility on computed tomography (CT) images and facilitated accurate PS placement were selected for the final PST design. An additive manufacturing machine (EOSINT M270) fabricated the PSTs using commercially pure titanium powder. For the clinical study, 36 scoliosis patients and 4 patients with ossification of the posterior longitudinal ligament (OPLL) were treated with thoracic PSs using our newly developed PSTs. We intraoperatively and postoperatively evaluated the accuracy of the PS hole created by the PST.
Based on the segmentation reproducibility and stability analyses, we selected seven small, round contact points for our PST: bilateral superior and inferior points on the transverse process base, bilateral inferior points on the laminar, and a superior point on the spinous process. Clinically, the success rates of PS placement using this PST design were 98.6 % (414/420) for scoliosis patients and 100 % (46/46) for OPLL patients.
This study provides a useful design concept for the development and introduction of patient-specific navigational templates for placing PSs.
已描述了用于椎弓根螺钉（PS）置入的基于图像的导航患者特异性模板（PST）。随着三维计算机辅助设计和增材制造技术的最新进展，已报道了各种PST设计，尽管模板设计未得到优化。我们开发了一种新颖的PST设计，该设计在不牺牲稳定性的情况下减少了接触面积。它避免了对介入软组织的敏感性、模板几何形状不准确以及模板拟合过程中的困难。
评估了椎骨后侧的14个候选位置。其中，在计算机断层扫描（CT）图像上具有高重复性且便于准确置入PS的位置被选用于最终的PST设计。一台增材制造机器（EOSINT M270）使用商业纯钛粉制造PST。对于临床研究，36例脊柱侧弯患者和4例后纵韧带骨化（OPLL）患者使用我们新开发的PST进行了胸椎PS置入治疗。我们在术中及术后评估了由PST创建的PS孔的准确性。
基于分割重复性和稳定性分析，我们为PST选择了七个小的圆形接触点：横突基部的双侧上、下点，椎板的双侧下点以及棘突上的一个上点。临床上，使用这种PST设计进行PS置入的成功率对于脊柱侧弯患者为98.6%（414/420），对于OPLL患者为100%（46/46）。
本研究为开发和引入用于置入PS的患者特异性导航模板提供了有用的设计概念。
