PURPOSE Insertion trajectory affects final intracochlear cochlear implant (CI) positioning, but limited information is available intraoperatively regarding ideal trajectory. We sought to improve intracochlear positioning CI electrodes using custom templates to specify insertion trajectory. METHODS 3D reconstructions were created from computed tomography of three cadaveric temporal bones. Trajectories co-planar with the straight segment of the cochlea's basal turn were considered ideal. Templates were designed to fit against the drilled mastoid's surface and convey this guided trajectory via a hollow cylinder. Templates were 3D-printed using stereolithography. Mastoidectomy was performed. Template accuracy was tested by measuring target registration error (TRE) for four templates. A novel, roller-based insertion tool (designed to fit within the template cylinder) constrained insertions to intended trajectories. Insertions were performed with MED-EL Standard electrodes in three bones with three conditions: guided trajectory with insertion tool, non-guided trajectory with insertion tool and guided trajectory with surgical forceps. For the final condition, the template was used to mark the mastoid to convey trajectory. Insertion was stopped when electrode buckling occurred. RESULTS TRE ranged from 0.23 to 0.73 mm. Mean TRE ± standard deviation was 0.55 ± 0.19 mm. Insertions along guided versus non-guided trajectories averaged more intracochlear electrodes (9, 8, 8 vs. 7, 7, 8) and greater angular insertion depths (AID) (377°, 341°, 320° vs. 278°, 302°, 290°). Insertions performed with forceps using templates as a guide also achieved excellent results (intracochlear electrodes: 10, 7, 8; AID: 478°, 318°, 333°). No translocations occurred. CONCLUSION Custom mastoid-fitting templates reliably specify intended insertion trajectory and provide sufficient information for recreation of that trajectory with manual insertion after template removal. The templates can accurately target structures within the temporal bone with a TRE of 0.55 ± 0.19 mm. Our roller-based insertion tool achieves results comparable to manual insertion using surgical forceps.

中文翻译：

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用于改善人工耳蜗植入电极插入轨迹的定制乳突拟合模板。

目的 插入轨迹会影响最终的人工耳蜗内人工耳蜗 (CI) 定位，但关于理想轨迹的术中可用信息有限。我们试图使用自定义模板来指定插入轨迹来改进耳蜗内定位 CI 电极。方法 3D 重建是从三个尸体颞骨的计算机断层扫描中创建的。与耳蜗基底转向的直线段共面的轨迹被认为是理想的。模板旨在贴合钻孔乳突的表面，并通过空心圆柱体传达此引导轨迹。模板是使用立体光刻技术 3D 打印的。进行了乳突切除术。通过测量四个模板的目标配准误差 (TRE) 来测试模板准确性。一本小说，基于滚轮的插入工具（设计用于安装在模板圆柱体内）将插入限制在预期的轨迹上。在三种情况下使用 MED-EL 标准电极在三个骨骼中执行插入：使用插入工具的引导轨迹、使用插入工具的非引导轨迹和使用手术钳的引导轨迹。对于最终条件，模板用于标记乳突以传达轨迹。当电极发生屈曲时停止插入。结果 TRE 范围从 0.23 到 0.73 毫米。平均 TRE ± 标准偏差为 0.55 ± 0.19 毫米。沿引导与非引导轨迹插入平均更多的耳蜗内电极（9、8、8 对 7、7、8）和更大的插入角度（AID）（377°、341°、320° 对 278°、302°） , 290°）。使用模板作为指导用镊子进行的插入也取得了优异的结果（耳蜗内电极：10、7、8；辅助：478°、318°、333°）。没有发生易位。结论 定制的乳突拟合模板可靠地指定了预期的插入轨迹，并为在模板移除后通过手动插入重新创建该轨迹提供了足够的信息。模板可以准确地定位颞骨内的结构，TRE 为 0.55 ± 0.19 毫米。我们基于滚轮的插入工具的效果可与使用手术钳手动插入的结果相媲美。结论 定制的乳突拟合模板可靠地指定了预期的插入轨迹，并为在模板移除后通过手动插入重新创建该轨迹提供了足够的信息。模板可以准确地定位颞骨内的结构，TRE 为 0.55 ± 0.19 毫米。我们基于滚轮的插入工具的效果可与使用手术钳手动插入的结果相媲美。结论 定制的乳突拟合模板可靠地指定了预期的插入轨迹，并为在模板移除后通过手动插入重新创建该轨迹提供了足够的信息。模板可以准确地定位颞骨内的结构，TRE 为 0.55 ± 0.19 毫米。我们基于滚轮的插入工具的效果可与使用手术钳手动插入的结果相媲美。