Kobler Jan-Philipp, Nuelle Kathrin, Lexow G Jakob, Rau Thomas S, Majdani Omid, Kahrs Lueder A, Kotlarski Jens, Ortmaier Tobias
Institute of Mechatronic Systems, Leibniz Universität Hannover, 30167 , Hanover, Germany.
Hannover Medical School, 30625 , Hanover, Germany.
Int J Comput Assist Radiol Surg. 2016 Mar;11(3):421-36. doi: 10.1007/s11548-015-1300-4. Epub 2015 Sep 26.
Minimally invasive cochlear implantation is a novel surgical technique which requires highly accurate guidance of a drilling tool along a trajectory from the mastoid surface toward the basal turn of the cochlea. The authors propose a passive, reconfigurable, parallel robot which can be directly attached to bone anchors implanted in a patient's skull, avoiding the need for surgical tracking systems. Prior to clinical trials, methods are necessary to patient specifically optimize the configuration of the mechanism with respect to accuracy and stability. Furthermore, the achievable accuracy has to be determined experimentally.
A comprehensive error model of the proposed mechanism is established, taking into account all relevant error sources identified in previous studies. Two optimization criteria to exploit the given task redundancy and reconfigurability of the passive robot are derived from the model. The achievable accuracy of the optimized robot configurations is first estimated with the help of a Monte Carlo simulation approach and finally evaluated in drilling experiments using synthetic temporal bone specimen.
Experimental results demonstrate that the bone-attached mechanism exhibits a mean targeting accuracy of [Formula: see text] mm under realistic conditions. A systematic targeting error is observed, which indicates that accurate identification of the passive robot's kinematic parameters could further reduce deviations from planned drill trajectories.
The accuracy of the proposed mechanism demonstrates its suitability for minimally invasive cochlear implantation. Future work will focus on further evaluation experiments on temporal bone specimen.
微创人工耳蜗植入是一种新型手术技术，需要沿着从乳突表面到耳蜗基底转的轨迹对钻孔工具进行高度精确的引导。作者提出了一种被动、可重构的并联机器人，它可以直接连接到植入患者颅骨的骨锚上，无需手术跟踪系统。在进行临床试验之前，需要有方法针对患者具体优化该机构在精度和稳定性方面的配置。此外，必须通过实验确定可达到的精度。
建立了所提出机构的综合误差模型，考虑了先前研究中确定的所有相关误差源。从该模型中得出了两个利用给定任务冗余性和被动机器人可重构性的优化标准。首先借助蒙特卡洛模拟方法估计优化后的机器人配置可达到的精度，最后使用合成颞骨标本进行钻孔实验进行评估。
实验结果表明，在实际条件下，骨附着机构的平均靶向精度为[公式：见正文]毫米。观察到存在系统靶向误差，这表明准确识别被动机器人的运动学参数可进一步减少与计划钻孔轨迹的偏差。
所提出机构的精度证明了其适用于微创人工耳蜗植入。未来的工作将集中在对颞骨标本进行进一步的评估实验上。
