Robotic CI surgery – but with the robot put aside
Samuel John, OtoJig GmbH, Hanover, Germany, john.samuel@otojig.com Marcel Kluge, OtoJig GmbH, Hanover, Germany, kluge.marcel@otojig.com Felix Repp, OtoJig GmbH, Hanover, Germany, repp.felix@otojig.com Jan Stieghorst, OtoJig GmbH, Hanover, Germany, stieghorst.jan@otojig.com
Thomas Lenarz, Hannover Medical School (Department of Otolaryngology), Hanover, Germany, lenarz.thomas@mh- hannover.de
Introduction
Surgical robotics are, without a doubt, a hot topic in ENT and other disciplines, and it will become a reality in the field of cochlear implant (CI) surgery. But it is also a very controversial one and triggers high expectations on the one side while robots bear a high intrinsic risk on the other side.
The biggest problem of present day robotic systems is navigating — in real time and high resolution — in the human body. However, CI surgery is a special case because of three reasons. First, the target and risk structures are embedded in the temporal bone and therefore not moving, which allows to register and plan in relation to the temporal bone.
Second, is it possible to reach the target with a straight access path. Third, a very high accuracy of better than 0.5 mm is required. Therefore, all promising approaches include the use of bone anchoring for registration and navigation.
Methods
We propose to use the bone screws to fixate a mini-stereotactic frame that can be used as a ‘frame of reference’ in order to move the surgical robot away from the patient and instead use the robot to prepare an individualized drilling tem- plate, called a jig. Our suggestion consists of a planning software, a mini-stereotactic frame, a patient individualized drilling jig, special drill bits, and an insertion tool to perform high precision and safe minimally invasive CI surgery.
Here we report of the latest N=4 tests on full body donors to evaluate the system design in a OR-like setting.
Results
The robot in our scenario is not directly at the patient but on-site to manufacture on-demand during the surgery. Instead of a serial kinematic, we employ a hexapod robotic platform and a linear drive to produce the patient-individual drilling jigs. The steady progress in image quality and resolution of intra operative DVT imaging allows for precise planning of CI surgery. To bring this high precision planning to the patient, we localize the mini-stereotactic frame in the radiologic volume image and compute the relative position of the planned path. This information is used to produce a drilling jig, that can be verified prior to use at the patient. The participating surgeons evaluated the developed system as a feasible method for future routine CI surgery.
Conclusion
We present our take on high precision robotic CI surgery. By decoupling the robot from the patient, we can reduce the risk of uncontrolled or unintended robot movements, that could potentially lead to harm for the patient. Still surgeons and patients can get the benefits of robotics with respect to high precision drilling and automation.
Robotic milling of the electrode lead channel during cochlear implantation
Jan Hermann, ARTORG Center for Biomedical Engineering Research, Bern, Switzerland, jan.hermann@artorg.unibe.ch Fabian Müller, ARTORG Center for Biomedical Engineering Research, Bern, Switzerland, fabian.mueller@ar- torg.unibe.ch
Gabriela O’Toole Bom Braga, ARTORG Center for Biomedical Engineering Research, Bern, Switzerland,ga- briela.braga@artorg.unibe.ch
Stefan Weber, ARTORG Center for Biomedical Engineering Research, Bern, Switzerland, stefan.weber@artorg.unibe.ch
Introduction
Robotic cochlear implantation has been developed to overcome the limits of human perception and dexterity due to the submillimeter size of the targeted anatomy. During this procedure, the robot precisely drills a small-diameter access hole to the cochlea. Since there is no cavity like the mastoidectomy in the conventional surgery, and the robotic system is already installed, we propose to robotically mill the electrode lead channel on the temporal bone surface. The goal is to further standardise the procedure, ensure protection of the electrode from trauma, and prevent fatigue fractures caused by micro-movements. We propose a workflow consisting of preoperative planning on cone-beam computed tomography and its robotic execution. The planning provides a low-curvature channel of sufficient depth below the temporal bone surface, with a channel shape designed to immobilize the electrode with a slight press-fit.
Methods
This workflow was planned for three ex-vivo human cephalic specimens, considering a safety margin of 1.0 mm from the channel to surrounding anatomical and artificial structures. The planning was then executed using a commercially available robotic system. To evaluate safety and efficacy, the lateral and depth displacement of the resulting channel, as well as the channel depth and width were measured in a micro-computed tomography scan.
Results
Three out of the three cases have been successfully completed, and the electrode leads could be gently embedded within the resulting channels. The mean lateral and depth displacements were -0.05 ± 0.06 mm standard deviation (SD), and -0.06 ± 0.14 mm (SD), respectively. The resulting channel never left the planned safety margin. The mean channel width was measured to be 1.19 ± 0.06 mm (SD), where the planned channel width and tool diameter was 1.2 mm. The mean channel depth was measured to be 2.41 ± 0.13 mm (SD), where the planned channel depth was 2.3 mm.
Conclusion
This study proposes the robotic creation of a channel for cochlear implant electrode leads, which has been shown to be safe and effective in an ex-vivo model. The proposed procedure step could further standardize cochlear implantation and provide for a decreased risk of device failure due to trauma or fatigue, thus potentially leading to increased implant longevity.
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Reliability of start and stop control of hydraulic actuation for the in- sertion of electrode arrays
M. Geraldine Zuniga, Department of Otolaryngology and Cluster of Excellence EXC 2177/1 “Hearing4all”, Hannover Medical School, Hanover, Germany, ZunigaManrique.Maria@mh-hannover.de
Viktor Schell, Department of Otolaryngology, Hannover Medical School, Hanover, Germany, schell.viktor@mh-hanno- ver.de
Jakob Cramer, Department of Otolaryngology, Hannover Medical School, Hanover, Germany, cramer.jakob@mh-han- nover.de
Thomas Lenarz, Department of Otolaryngology and Cluster of Excellence EXC 2177/1 “Hearing4all”, Hannover Medical School, Hanover, Germany, lenarz.thomas@mh-hannover.de
Thomas S. Rau, Department of Otolaryngology and Cluster of Excellence EXC 2177/1 “Hearing4all”, Hannover Medical School, Hanover, Germany, rau.thomas@mh-hannover.de
Introduction
Atraumatic insertions of electrode arrays (EA) into the cochlea aim to preserve natural structures and preserve residual hearing. However, there is a limit as to how smooth and slow a surgeon can insert an EA, regardless of skill level. As a potential solution, we recently presented a tool (cochlea hydro drive, CHD) that makes use of an infusion pump to prompt and control the desired, continuous and very slow (< 1 mm/s) forward movement for such insertions. The present work further describes the onset, delay and cessation of the hydraulic actuation in response to different start and stop mecha- nisms, to better understand the safety of its application for cochlear implant surgery.
Methods
Our previously designed tool was used to perform insertions of an EA into an artificial scala tympani model. The prototype is designed to hold an EA, which is then actuated by a standard infusion pump programmed to operate at 0.4 mm/ and 0.1 mm/s. A tubing system between the CHD and the pump includes a three-way valve. Ten insertions were operated using the functions of the pump and ten using the valve.
Results
From the programmed start to the actual movement, we observed a larger average delay using the pump’s start function (5 s at 0.4 mm/s; 17 s at 0.1 mm/s) vs. opening the valve (< 0.7 s for both velocities). Moreover, the average cessation of movement with the valve closure was almost immediate (0.7 s for both velocities; this corresponds to < 0.1 mm with the slower tested velocity), as opposed to 60-80 s delay when using the pump’s stop function.
Conclusion
The use of a 3-way valve facilitates motion cessation to the high accuracy level required for cochlear implant surgery.
These promising findings support future clinical translation of our tool.
Design and first evaluation of a manual insertion tool enabling force measurements during cochlear implant electrode array insertion
Georg Böttcher, Department of Otolaryngology Hannover Medical School, Hanover, Germany, boettcher.georg@mh- hannover.de
Viktor Schell, Department of Otolaryngology Hannover Medical School, Hanover, Germany, schell.viktor@mh- hannover.de
Leon Budde, Institute of Mechatronic Systems, Leibniz Universität Hannover, Hanover, Germany, le- on.budde@imes.uni-hannover.de
Claas Baier, Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hanover, Ger- many, baier.claas@mh-hannover.de
Thomas Lenarz, Department of Otolaryngology and Cluster of Excellence EXC 2177/1 “Hearing4all”, Hannover Medi- cal School, Hanover, Germany, rau.thomas@mh-hannover.de
Geraldine Zuniga, Department of Otolaryngology and Cluster of Excellence EXC 2177/1 “Hearing4all”, Hannover Medical School, Hanover, Germany, rau.thomas@mh-hannover.de
Thomas Rau, Department of Otolaryngology and Cluster of Excellence EXC 2177/1 “Hearing4all”, Hannover Medical School, Hanover, Germany, rau.thomas@mh-hannover.de
Introduction
The magnitude of forces acting during electrode array insertion in cochlear implant surgery is closely linked to residual hearing preservation. While these forces have been investigated in vitro, the applied models cannot be verified as no in vivo insertion force measurements have yet been performed. In vivo force measurements could also assist surgeons as critical force thresholds just barely exceed human perception.
Methods
A manual insertion tool with an embedded force sensor was developed. Its design is optimized for intraoperative use ensuring patient safety while providing reliable data. As gravity influences the measurement when the tool is moved, an inertial measurement unit (IMU) was included to compute a corrected force signal. The tool’s measurements in an arti- ficial cochlea model (ACM) were compared to the gold standard which uses an external sensor beneath the ACM. Sur- gical tool handling was preliminarily evaluated through insertions in a cadaver head.
Results
Orientation-related errors of up to 3 mN caused by small orientation changes of up to 5° for ACM insertions were re- moved from the original force signal. Corrected forces recorded with the tool correspond well to externally measured control forces with a median difference of 0.2 mN and an interquartile range of 1.9 mN. The cadaveric insertions showed an increased range of motion resulting in larger orientation-related errors compared to ACM insertions. In both experimental setups, full insertions were successfully achieved with the tool.
Conclusion
The evaluation of the proposed manual insertion tool design proves the feasibility of intraoperative insertion force measurements. Forces were recorded with an accuracy equivalent to test bench setups which currently cannot provide manual in vitro measurements. Successful cadaveric insertions and positive handling evaluation suggest good transfera- bility to the OR. This tool’s data could prospectively be used to assist surgeons and to prevent injury by warning about force thresholds.
Near-UV to near-IR multispectral illumination in a digital microscope
Eric L. Wisotzky, Fraunhofer Heinrich-Hertz-Institut HHI, Berlin, Germany eric.wisotzky@hhi.fraunhofer.de, Florian C.
Uecker, Charité Universitätsmedizin, Berlin, Germany, fc.uecker@charite.de, Jean-Claude Rosenthal, Fraunhofer Hein- rich-Hertz-Institut HHI, Berlin, Germany jean-claude.rosenthal@hhi.fraunhofer.de, Philipp Arens, Charité Universitäts- medizin, Berlin, Germany, philipp.arens@charite.de, Armin Schneider, Munich Surgical Imaging GmbH, Munich, Ger- many, aschneider@munichimaging.de
Introduction
Digitization creates new possibilities to support the surgeon in complex surgical processes. On one hand, digital surgical microscopy makes a three-dimensional (3D) reconstruction of the situs possible. In addition, spectral imaging can be used to detect optical tissue properties that are normally invisible to the human eye. The additional information can support the decision-making process and facilitate the surgical procedure when using appropriate intraoperative real-time visualiza- tions.
Methods
A fully-digital surgical microscope is equipped with a multispectral illumination unit allowing additional narrow-band lightning in the range of near-UV (405nm) to near-IR (808nm). This additional LED light source is mounted on only one of the two light exits at the microscope head. This allows two different illumination modes: 1. either the normal white light of the microscope or a narrowband light illuminates the situs or 2. the normal white light of the microscope can be combined with an additional narrow-band illumination. This setup has been used during two cholesteatoma surgeries.
Results
Both illumination modes can highlight cholesteatoma. Near-UV to blue illumination only (Modus 1) results in higher reflectance of cholesteatoma compared to surrounding tissue, but the increased reflectance is not always distinguishable by the human eye, due to the weaker blue sensitifity of the eye, and needs additional postprocessing. If the situs is illu- minated with the near-UV in combination with low intensity white light (Modus 2), cholesteatoma shines bluish while bone remains white, which allows a direct tissue differentiation between cholesteatoma and bone.
Conclusion
This setup, a fully-digital surgical microscope equipped with an additional multispectral illumination allows different tissue types to be made more visually distinguishable through the illumination aligned to the different optical tissue prop- erties. Thus, surgical processes could be accelerated and revision procedures reduced for an improved patient outcome.
