An autonomous surgical robot for drilling a cochleostomy: preliminary porcine trial

Identification of milling status based on vibration signals using artificial intelligence in robot-assisted cervical laminectomy

BACKGROUND

With advances in science and technology, the application of artificial intelligence in medicine has significantly progressed. The purpose of this study is to explore whether the k-nearest neighbors (KNN) machine learning method can identify three milling states based on vibration signals: cancellous bone (CCB), ventral cortical bone (VCB), and penetration (PT) in robot-assisted cervical laminectomy.

METHODS

Cervical laminectomies were performed on the cervical segments of eight pigs using a robot. First, the bilateral dorsal cortical bone and part of the CCB were milled with a 5 mm blade and then the bilateral laminae were milled to penetration with a 2 mm blade. During the milling process using the 2 mm blade, the vibration signals were collected by the acceleration sensor, and the harmonic components were extracted using fast Fourier transform. The feature vectors were constructed with vibration signal amplitudes of 0.5, 1.0, and 1.5 kHz and the KNN was then trained by the features vector to predict the milling states.

RESULTS

The amplitudes of the vibration signals between VCB and PT were statistically different at 0.5, 1.0, and 1.5 kHz (P < 0.05), and the amplitudes of the vibration signals between CCB and VCB were significantly different at 0.5 and 1.5 kHz (P < 0.05). The KNN recognition success rates for the CCB, VCB, and PT were 92%, 98%, and 100%, respectively. A total of 6% and 2% of the CCB cases were identified as VCB and PT, respectively; 2% of VCB cases were identified as PT.

CONCLUSIONS

The KNN can distinguish different milling states of a high-speed bur in robot-assisted cervical laminectomy based on vibration signals. This method is feasible for improving the safety of posterior cervical decompression surgery.

Bridging Reinforcement Learning and Iterative Learning Control: Autonomous Motion Learning for Unknown, Nonlinear Dynamics

This work addresses the problem of reference tracking in autonomously learning robots with unknown, nonlinear dynamics. Existing solutions require model information or extensive parameter tuning, and have rarely been validated in real-world experiments. We propose a learning control scheme that learns to approximate the unknown dynamics by a Gaussian Process (GP), which is used to optimize and apply a feedforward control input on each trial. Unlike existing approaches, the proposed method neither requires knowledge of the system states and their dynamics nor knowledge of an effective feedback control structure. All algorithm parameters are chosen automatically, i.e. the learning method works plug and play. The proposed method is validated in extensive simulations and real-world experiments. In contrast to most existing work, we study learning dynamics for more than one motion task as well as the robustness of performance across a large range of learning parameters. The method’s plug and play applicability is demonstrated by experiments with a balancing robot, in which the proposed method rapidly learns to track the desired output. Due to its model-agnostic and plug and play properties, the proposed method is expected to have high potential for application to a large class of reference tracking problems in systems with unknown, nonlinear dynamics.

The Advances in Computer Vision That Are Enabling More Autonomous Actions in Surgery: A Systematic Review of the Literature

This is a review focused on advances and current limitations of computer vision (CV) and how CV can help us obtain to more autonomous actions in surgery. It is a follow-up article to one that we previously published in Sensors entitled, “Artificial Intelligence Surgery: How Do We Get to Autonomous Actions in Surgery?” As opposed to that article that also discussed issues of machine learning, deep learning and natural language processing, this review will delve deeper into the field of CV. Additionally, non-visual forms of data that can aid computerized robots in the performance of more autonomous actions, such as instrument priors and audio haptics, will also be highlighted. Furthermore, the current existential crisis for surgeons, endoscopists and interventional radiologists regarding more autonomy during procedures will be discussed. In summary, this paper will discuss how to harness the power of CV to keep doctors who do interventions in the loop.

Image-Based Planning of Minimally Traumatic Inner Ear Access for Robotic Cochlear Implantation

Objective: During robotic cochlear implantation, an image-guided robotic system provides keyhole access to the scala tympani of the cochlea to allow insertion of the cochlear implant array. To standardize minimally traumatic robotic access to the cochlea, additional hard and soft constraints for inner ear access were proposed during trajectory planning. This extension of the planning strategy aims to provide a trajectory that preserves the anatomical and functional integrity of critical intra-cochlear structures during robotic execution and allows implantation with minimal insertion angles and risk of scala deviation.

Methods: The OpenEar dataset consists of a library with eight three-dimensional models of the human temporal bone based on computed tomography and micro-slicing. Soft constraints for inner ear access planning were introduced that aim to minimize the angle of cochlear approach, minimize the risk of scala deviation and maximize the distance to critical intra-cochlear structures such as the osseous spiral lamina. For all cases, a solution space of Pareto-optimal trajectories to the round window was generated. The trajectories satisfy the hard constraints, specifically the anatomical safety margins, and optimize the aforementioned soft constraints. With user-defined priorities, a trajectory was parameterized and analyzed in a virtual surgical procedure.

Results: In seven out of eight cases, a solution space was found with the trajectories safely passing through the facial recess. The solution space was Pareto-optimal with respect to the soft constraints of the inner ear access. In one case, the facial recess was too narrow to plan a trajectory that would pass the nerves at a sufficient distance with the intended drill diameter. With the soft constraints introduced, the optimal target region was determined to be in the antero-inferior region of the round window membrane.

Conclusion: A trend could be identified that a position between the antero-inferior border and the center of the round window membrane appears to be a favorable target position for cochlear tunnel-based access through the facial recess. The planning concept presented and the results obtained therewith have implications for planning strategies for robotic surgical procedures to the inner ear that aim for minimally traumatic cochlear access and electrode array implantation.

Literature Review on Endoscopic Robotic Systems in Ear and Sinus Surgery

In otolaryngologic surgery, endoscopy is increasingly used to provide a better view of hard-to-reach areas and to promote minimally invasive surgery. However, the need to manipulate the endoscope limits the surgeon's ability to operate with only one instrument at a time. Currently, several robotic systems are being developed, demonstrating the value of robotic assistance in microsurgery. The aim of this literature review is to present and classify current robotic systems that are used for otological and endonasal applications. For these solutions, an analysis of the functionalities in relation to the surgeon's needs will be carried out to produce a set of specifications for the creation of new robots.

The Use of a Robot to Insert an Electrode Array of Cochlear Implants in the Cochlea: A Feasibility Study and Preliminary Results

INTRODUCTION

Cochlear implants (CIs) are commonly used for the rehabilitation of profound bilateral hearing loss. However, patients with substantial residual acoustic hearing are potential CI candidates. Because of both improvements in technology and advancements in surgical techniques, it may be possible to preserve hearing to some extent. For more than a decade, it has been suggested that robots are used to perform middle ear surgery. We evaluated the use of the RobOtol® otologic robot specifically to insert CI electrodes into the inner ear.

METHODS

CI surgery with the conventional approach was performed under general anesthesia. The MED-El Flex 24-electrode array was inserted using RobOtol®. Video recordings were used to calculate the speed of insertion. The positions of the electrodes were evaluated using a cone beam CT. All subjects underwent pure-tone audiometry tests before and after surgery, and the pure-tone average (PTA) was calculated from 250 to 4,000 Hz.

RESULTS

The robot inserted implants in 5 patients, and complete insertion of the electrode array was achieved. The speed of insertion of the electrode array was 0.88 ± 0.12 mm/s. The mean loss of the PTA for 5 frequencies (250, 500, 1,000, 2,000, and 4,000 Hz) was 13.60 ± 7.70 dB. Only 1 patient showed a loss of the PTA by >20 dB. For these 5 patients, the cone beam CT findings showed that all the electrode arrays were in the tympanic ramp and had a grade of 0. The results were compared with those obtained from a cohort of 17 patients who underwent manual implantation of a MED-El Flex 24-electrode array.

CONCLUSION

To minimize disturbance to the cochlea while atraumatic electrode arrays are inserted, electrodes can be inserted at a constant, slow speed in the inner ear with the assistance of the RobOtol® robot in a normal clinical surgical setting.

Human-Inspired Haptic Perception and Control in Robot-Assisted Milling Surgery

Bone milling is one of the most widely used and high-risk procedures in various types of surgeries, and it is important to be noted that the experienced surgeon can perform such an operation safely. The objective of this article is to enhance the safety of the robot-assisted milling operation with the inspiration of human haptic perception. The emergence, coding and perception of the human haptic are introduced. Following this, a single axis accelerometer that measures the vibration of the surgical power tool is mounted in the robot arm, and the recorded acceleration signal is encoded as parallel stream of binary data. The data are subsequently inputted to the Hopfield network so as to identify the milling state. Inspired by human inference procedure, the fuzzy logic controller is introduced to control the robot to track the desired state when performing bone milling operations. A real-time implementation of the proposed method on a digital signal processing is also described. The experimental results in milling porcine spines prove that the robot accurately discriminates different milling states even when the additive noise is serious, and the safe motion control of the robot is also realized.

Production of gene-edited pigs harboring orthologous human mutations via double cutting by CRISPR/Cas9 with long single-stranded DNAs as homology-directed repair templates by zygote injection

Precise gene editing of model organisms is required for accurately modeling human diseases and deciphering gene functions. In this study, we used a pair of guide RNAs (sgRNAs), which in vitro transcribed along with other CRISPR RNA components, to generate two cleavage sites flanking pig GJB2 (pGJB2) CDS. By using long single-stranded DNAs (lssDNA) as homology-directed repair (HDR) templates, we efficiently obtained two gene-edited pigs, of which GJB2 CDS replaced with CDSs containing human GJB2 c.235delC mutation and orthologous human p.V37I mutation, respectively. These mutations were commonly observed in patients with hearing loss. Genetic analysis of the two gene-edited pigs showed that the HDR-derived gene-editing efficiency were as high as 80% (4/5) and 50% (2/4), respectively. While no mutation was observed in the group of single cutting with one sgRNA covering the 235th nucleotide C in pGJB2 CDS, using a short single-stranded oligo DNA containing c.235delC mutation as HDR template. Extra experiments proved that the intended mutations were successfully transmitted to offspring or extensively integrated into various tissues including gonad of founder pigs. Our work indicated that the new "double cutting with lssDNA template" gene editing method can expand sgRNA selection scope and avoids direct cutting of gene CDS. Additionally, can introduce precise mutations into mammalian genomic sites, especially those with unavailable proper protospacer sequence or being resistant to gene editing. Moreover, this method can be performed with CRISPR RNA reagents instead of CRISPR ribonucleoproteins applied in previous reports.

Supervised Autonomous Electrosurgery via Biocompatible Near-Infrared Tissue Tracking Techniques

Autonomous robotic surgery systems aim to improve patient outcomes by leveraging the repeatability and consistency of automation and also reducing human induced errors. However, intraoperative autonomous soft tissue tracking and robot control still remains a challenge due to the lack of structure, and high deformability of such tissues. In this paper, we take advantage of biocompatible Near-Infrared (NIR) marking methods and develop a supervised autonomous 3D path planning, filtering, and control strategy for our Smart Tissue Autonomous Robot (STAR) to enable precise and consistent incisions on complex 3D soft tissues. Our experimental results on cadaver porcine tongue samples indicate that the proposed strategy reduces surface incision error and depth incision error by 40.03% and 51.5%, respectively, compared to a teleoperation strategy via da Vinci. Furthermore, compared to an autonomous path planning method with linear interpolation between the NIR markers, the proposed strategy reduces the incision depth error by 48.58% by taking advantage of 3D tissue surface information.

Utilization of a robotic mount to determine the force required to cut palatal tissue

Determination of the material properties of soft tissue is a growing area of interest that aids in the development of new surgical tools and surgical simulators. This study first aims to develop a robot-operated tissue testing system for determination of tissue cutting forces. Second, this system was used to ascertain the cutting properties of the hard and soft palate mucosa and soft palate musculature for the purpose of developing a robotic instrument for cleft palate surgery and a cleft-specific surgical simulator. The palate tissue was cut with a 15 blade mounted to the robot with varying angles (30°, 60°, 90°) and speeds (1.5, 2.5, 3.5 cm/s) of cutting to imitate typical operative tasks. The cutting force range for hard palate mucosa, soft palate mucosa and soft palate muscle were 0.98-3.30, 0.34-1.74 and 0.71-2.71 N, respectively. The break-in force of the cut (i.e. force required for the blade to penetrate the tissue) is significantly impacted by the angle of the blade relative to the tissue rather than the cutting speed. Furthermore, the total surface area of the tissue in contact with the blade during the cut has a significant impact on the total force expended on the tissue.

Outlook and future of inner ear therapy

Drug delivery to the inner ear is an ideal method to treat a wide variety of otologic conditions. A broad range of potential applications is just beginning to be explored. New approaches combine principles of inner ear pharmacokinetics with emerging technologies of drug delivery including novel delivery systems, drug-device combinations, and new categories of drugs. Strategies include cell-specific targeting, manipulation of gene expression, local activation following systemic delivery, and use of stem cells, viral vectors, and gene editing systems. Translation of these therapies to the clinic remains challenging given the potential risks of intracochlear and intralabyrinthine trauma, our limited understanding of the etiologies of particular inner ear disorders, and paucity of accurate diagnostic tools at the cellular level. This review provides an overview of future methods, delivery systems, disease targets, and clinical considerations required for translation to clinical medicine.

Semi-Autonomous Laparoscopic Robotic Electro-surgery with a Novel 3D Endoscope

This paper reports a robotic laparoscopic surgery system performing electro-surgery on porcine cadaver kidney, and evaluates its accuracy in an open loop control scheme to conduct targeting and cutting tasks guided by a novel 3D endoscope. We describe the design and integration of the novel laparoscopic imaging system that is capable of reconstructing the surgical field using structured light. A targeting task is first performed to determine the average positioning error of the system as guided by the laparoscopic camera. The imaging system is then used to reconstruct the surface of a porcine cadaver kidney, and generate a cutting trajectory with consistent depth. The paper concludes by using the robotic system in open loop control to cut this trajectory using a multi degree of freedom electro-surgical tool. It is demonstrated that for a cutting depth of 3 mm, the robotic surgical system follows the trajectory with an average depth of 2.44 mm and standard deviation of 0.34 mm. The average positional accuracy of the system was 2.74±0.99 mm.

Semi-Autonomous Electrosurgery for Tumor Resection Using a Multi-Degree of Freedom Electrosurgical Tool and Visual Servoing

This paper specifies a surgical robot performing semi-autonomous electrosurgery for tumor resection and evaluates its accuracy using a visual servoing paradigm. We describe the design and integration of a novel, multi-degree of freedom electrosurgical tool for the smart tissue autonomous robot (STAR). Standardized line tests are executed to determine ideal cut parameters in three different types of porcine tissue. STAR is then programmed with the ideal cut setting for porcine tissue and compared against expert surgeons using open and laparoscopic techniques in a line cutting task. We conclude with a proof of concept demonstration using STAR to semi-autonomously resect pseudo-tumors in porcine tissue using visual servoing. When tasked to excise tumors with a consistent 4mm margin, STAR can semi-autonomously dissect tissue with an average margin of 3.67 mm and a standard deviation of 0.89mm.

A cadaver study of mastoidectomy using an image-guided human-robot collaborative control system

Objective

Surgical precision would be better achieved with the development of an anatomical monitoring and controlling robot system than by traditional surgery techniques alone. We evaluated the feasibility of robot‐assisted mastoidectomy in terms of duration, precision, and safety.

Study Design

Human cadaveric study.

Materials and Methods

We developed a multi‐degree‐of‐freedom robot system for a surgical drill with a balancing arm. The drill system is manipulated by the surgeon, the motion of the drill burr is monitored by the image‐guided system, and the brake is controlled by the robotic system. The system also includes an alarm as well as the brake to help avoid unexpected damage to vital structures. Experimental mastoidectomy was performed in 11 temporal bones of six cadavers. Parameters including duration and safety were assessed, as well as intraoperative damage, which was judged via pre‐ and post‐operative computed tomography.

Results

The duration of mastoidectomy in our study was comparable with that required for chronic otitis media patients. Although minor damage, such as dura exposure without tearing, was noted, no critical damage to the facial nerve or other important structures was observed. When the brake system was set to 1 mm from the facial nerve, the postoperative average bone thicknesses of the facial nerve was 1.39, 1.41, 1.22, 1.41, and 1.55 mm in the lateral, posterior pyramidal and anterior, lateral, and posterior mastoid portions, respectively.

Conclusion

Mastoidectomy can be successfully performed using our robot‐assisted system while maintaining a pre‐set limit of 1 mm in most cases. This system may thus be useful for more inexperienced surgeons.

Level of Evidence

NA.

Positioning Accuracy in Otosurgery Measured with Optical Tracking

Objectives

To assess positioning accuracy in otosurgery and to test the impact of the two-handed instrument holding technique and the instrument support technique on surgical precision. To test an otologic training model with optical tracking.

Study Design

In total, 14 ENT surgeons in the same department with different levels of surgical experience performed static and dynamic tasks with otologic microinstruments under simulated otosurgical conditions.

Methods

Tip motion of the microinstrument was registered in three dimensions by optical tracking during 10 different tasks simulating surgical steps such as prosthesis crimping and dissection of the middle ear using formalin-fixed temporal bone. Instrument marker trajectories were compared within groups of experienced and less experienced surgeons performing uncompensated or compensated exercises.

Results

Experienced surgeons have significantly better positioning accuracy than novice ear surgeons in terms of mean displacement values of marker trajectories. The instrument support and the two-handed instrument holding techniques significantly reduce surgeons’ tremor. The laboratory set-up presented in this study provides precise feedback for otosurgeons about their surgical skills and proved to be a useful device for otosurgical training.

Conclusions

Simple tremor compensation techniques may offer trainees the potential to improve their positioning accuracy to the level of more experienced surgeons. Training in an experimental otologic environment with optical tracking may aid acquisition of technical skills in middle ear surgery and potentially shorten the learning curve. Thus, simulated exercises of surgical steps should be integrated into the training of otosurgeons.

Advantages of a miniature pig model in research on human hereditary hearing loss

In medical laboratory animals, the pig is the closest species to human in evolution, except for primates. As an animal model, the pig is highly concerned by many scientists, including comparative biology, developmental biology, medical genetics. Rodents as animal model for human hearing defects has are poor producibility and reliability, due to differences in anatomical structure, evolutionary rate and metabolic rate, but these happens to be the advantages of the pig model. In this paper, we will summarize the application of miniature pig in the study of human hereditary deafness.

Surgical robotics beyond enhanced dexterity instrumentation: a survey of machine learning techniques and their role in intelligent and autonomous surgical actions

PURPOSE

Advances in technology and computing play an increasingly important role in the evolution of modern surgical techniques and paradigms. This article reviews the current role of machine learning (ML) techniques in the context of surgery with a focus on surgical robotics (SR). Also, we provide a perspective on the future possibilities for enhancing the effectiveness of procedures by integrating ML in the operating room.

METHODS

The review is focused on ML techniques directly applied to surgery, surgical robotics, surgical training and assessment. The widespread use of ML methods in diagnosis and medical image computing is beyond the scope of the review. Searches were performed on PubMed and IEEE Explore using combinations of keywords: ML, surgery, robotics, surgical and medical robotics, skill learning, skill analysis and learning to perceive.

RESULTS

Studies making use of ML methods in the context of surgery are increasingly being reported. In particular, there is an increasing interest in using ML for developing tools to understand and model surgical skill and competence or to extract surgical workflow. Many researchers begin to integrate this understanding into the control of recent surgical robots and devices.

CONCLUSION

ML is an expanding field. It is popular as it allows efficient processing of vast amounts of data for interpreting and real-time decision making. Already widely used in imaging and diagnosis, it is believed that ML will also play an important role in surgery and interventional treatments. In particular, ML could become a game changer into the conception of cognitive surgical robots. Such robots endowed with cognitive skills would assist the surgical team also on a cognitive level, such as possibly lowering the mental load of the team. For example, ML could help extracting surgical skill, learned through demonstration by human experts, and could transfer this to robotic skills. Such intelligent surgical assistance would significantly surpass the state of the art in surgical robotics. Current devices possess no intelligence whatsoever and are merely advanced and expensive instruments.

The evolving identity, capacity, and capability of the future surgeon

Technology has transformed surgery more within the last 30 years than the previous 2000 years of human history combined. These innovations have changed not only how the surgeon practices but have also altered the very essence of what it is to be a surgeon in the modern era. Beyond the industrial revolution, today's information revolution allows patients access to an abundance of easily accessible, unfiltered information which they can use to evaluate their surgical treatment, and truly participate in their personal care. We are entering yet another revolution specifically affecting surgeons, where the traditional surgical tools of our craft are becoming "smart." Intelligence in surgical tools and connectivity based on sensory data, processing, and analysis are enabling and enhancing a surgeon's capacity and capability. Given the tempo of change, within one generation the traditional role and identity of a surgeon will be fully transformed. In this article, the impact of the information revolution, technological advances combined with smart connectivity on the changing role of surgery will be considered.

Semi-autonomous Simulated Brain Tumor Ablation with RavenII Surgical Robot using Behavior Tree

Medical robots have been widely used to assist surgeons to carry out dexterous surgical tasks via various ways. Most of the tasks require surgeon's operation directly or indirectly. Certain level of autonomy in robotic surgery could not only free the surgeon from some tedious repetitive tasks, but also utilize the advantages of robot: high dexterity and accuracy. This paper presents a semi-autonomous neurosurgical procedure of brain tumor ablation using RAVEN Surgical Robot and stereo visual feedback. By integrating with the behavior tree framework, the whole surgical task is modeled flexibly and intelligently as nodes and leaves of a behavior tree. This paper provides three contributions mainly: (1) describing the brain tumor ablation as an ideal candidate for autonomous robotic surgery, (2) modeling and implementing the semi-autonomous surgical task using behavior tree framework, and (3) designing an experimental simulated ablation task for feasibility study and robot performance analysis.

Mechatronic feasibility of minimally invasive, atraumatic cochleostomy

Robotic assistance in the context of lateral skull base surgery, particularly during cochlear implantation procedures, has been the subject of considerable research over the last decade. The use of robotics during these procedures has the potential to provide significant benefits to the patient by reducing invasiveness when gaining access to the cochlea, as well as reducing intracochlear trauma when performing a cochleostomy. Presented herein is preliminary work on the combination of two robotic systems for reducing invasiveness and trauma in cochlear implantation procedures. A robotic system for minimally invasive inner ear access was combined with a smart drilling tool for robust and safe cochleostomy; evaluation was completed on a single human cadaver specimen. Access to the middle ear was successfully achieved through the facial recess without damage to surrounding anatomical structures; cochleostomy was completed at the planned position with the endosteum remaining intact after drilling as confirmed by microscope evaluation.

Influence of cochleostomy and cochlear implant insertion on drug gradients following intratympanic application in Guinea pigs

Locally applied drugs can protect residual hearing following cochlear implantation. The influence of cochlear implantation on drug levels in the scala tympani (ST) after round window application was investigated in guinea pigs using the marker trimethylphenylammonium (TMPA) measured in real time with TMPA-selective microelectrodes. TMPA concentration in the upper basal turn of the ST rapidly increased during implantation and then declined due to cerebrospinal fluid entering the ST at the cochlear aqueduct and exiting at the cochleostomy. The TMPA increase was found to be caused by the cochleostomy drilling if the burr tip partially entered the ST. TMPA distribution in the second turn was less affected by implantation procedures. These findings show that basal turn drug levels may be changed during implantation and the changes may need to be considered in the interpretation of therapeutic effects of drugs in conjunction with implantation.

Automated drill-stop by SVM classified audible signals

Neuroscience research often requires direct access to brain tissue in animal models which clearly requires opening of the protective cranium. Minimizing animal numbers requests only well-experienced surgeons, since clumsy performance may lead to premature death of the animal. To minimise those traumatic outcomes, an algorithmic approach for closed-loop control of our Spherical Assistant for Stereotaxic Surgery (SASSU) was designed. Controlling the surgical robot's micro-drill unit by audio pattern recognition proved to be a simple and reliable way to automatically stop the automated drill feed. Sound analysis based on the anatomical morphology of a rat skull was used to train a Support Vector Machine (SVM) classification of the time-frequency representations of the drill sound. Fully automated high throughput animal surgeries are the goal of this approach.

Comparison on intracochlear disturbances between drilling a manual and robotic cochleostomy

During cochlear implantation, hearing preservation is a concern. Minimizing disturbances to the cochlea and protection of the underlying endosteal membrane during the formation of a cochleostomy are considered important factors. The robotic micro-drill system tested in this article is the first example of an autonomous surgical drill successfully producing a cochleostomy, which keeps the underlying endosteal membrane intact. This study compares induced disturbances within the cochlea during formation of cochleostomy using the robotic micro-drill with that of conventional manual drilling. The disturbance of the endosteal membrane is measured using a Microscope Scanning Vibrometer at a third window, produced in the cochlea. Results show that the highest velocity amplitude measured was associated with manual drilling technique. The robotic micro-drill technique produced only about 1% of the peak velocity amplitude seen in manual drilling and exhibited much more uniform behaviour, while keeping the underlying membrane intact. The technique applied when using the robotic drill could be a major step in reducing the trauma to the cochlea, by reducing disturbance levels.

Robotic endoscopic sinus and skull base surgery: review of the literature and future prospects

OBJECTIVE

There has been a considerable growth in the indications of endonasal surgery that now include malignant tumours of the nasal fossae and anterior and middle cranial fossa. However, new limitations have also been identified, such as bleeding and cerebrospinal fluid leak, as well as the need to use several instruments simultaneously. Can robotics provide solutions to these problems?

METHOD

Review of the literature based on the three main databases: Medline, Pubmed and Cochrane.

RESULTS

Ten publications were identified. Some authors have developed surgical approaches to the skull base using the da Vinci(®) robot, while others have designed specific robots.

CONCLUSION

None of the currently available solutions appears to be completely suitable. The da Vinci(®) robot is very cumbersome and can only be used in the middle cranial fossa via complex and relatively invasive routes. The other robots are laboratory prototypes. We are currently developing an innovative, compact, ergonomic and safe dedicated endoscope holder.

Three-dimensional histological specimen preparation for accurate imaging and spatial reconstruction of the middle and inner ear

PURPOSE

This paper presents a highly accurate cross-sectional preparation technique. The research aim was to develop an adequate imaging modality for both soft and bony tissue structures featuring high contrast and high resolution. Therefore, the advancement of an already existing micro-grinding procedure was pursued. The central objectives were to preserve spatial relations and to ensure the accurate three-dimensional reconstruction of histological sections.

METHODS

Twelve human temporal bone specimens including middle and inner ear structures were utilized. They were embedded in epoxy resin, then dissected by serial grinding and finally digitalized. The actual abrasion of each grinding slice was measured using a tactile length gauge with an accuracy of one micrometre. The cross-sectional images were aligned with the aid of artificial markers and by applying a feature-based, custom-made auto-registration algorithm. To determine the accuracy of the overall reconstruction procedure, a well-known reference object was used for comparison. To ensure the compatibility of the histological data with conventional clinical image data, the image stacks were finally converted into the DICOM standard.

RESULTS

The image fusion of data from temporal bone specimens' and from non-destructive flat-panel-based volume computed tomography confirmed the spatial accuracy achieved by the procedure, as did the evaluation using the reference object.

CONCLUSION

This systematic and easy-to-follow preparation technique enables the three-dimensional (3D) histological reconstruction of complex soft and bony tissue structures. It facilitates the creation of detailed and spatially correct 3D anatomical models. Such models are of great benefit for image-based segmentation and planning in the field of computer-assisted surgery as well as in finite element analysis. In the context of human inner ear surgery, three-dimensional histology will improve the experimental evaluation and determination of intra-cochlear trauma after the insertion of an electrode array of a cochlear implant system.

Use of wavelet energy for spinal cord vibration analysis during spinal surgery

BACKGROUND

An online non-contact measurement system using a laser displacement sensor was developed for obtaining the vibration amplitude of spinal cord and hard tissue.

METHODS

The discrete wavelet transform was used to extract the distinctive features of tissue vibration signals. The spinal cord and spinal cancellous bone can be discriminated by the comparison of wavelet energy over a characteristic scale. We also derived the integro-differential equation of motion to describe the spinal cord vibration excited by the motion of bone.

RESULTS

Experimental results show that the method works well in identifying spinal cord and bone. However, available viscoelastic constants cannot describe the high-frequency features of spinal cord.

CONCLUSIONS

The examined issue of tissue vibration due to the operation power device is a significant problem. The proposed method can be used by a surgery robot, and then spinal surgery may greatly benefit from the enhanced safety of robotics.

Measurement of osteotomy force during endoscopic sinus surgery

Greater understanding of the surgeon's task and skills are required to improve surgical technique and the effectiveness of training. Currently, neither the objective measurement of osteotomy forces during endoscopic sinus surgery (ESS) nor the validity of the properties of cadaver materials, are well documented. Measurement was performed of peak axial osteotomy force during ESS. A comparison was made of results with previously published cadaver data to validate the force properties of cadaver models. A prospective, consecutive cohort of 25 patients was compared with data from 15 cadaver heads. A modified Storz sinus curette measured osteotomy force from uncinate, bulla ethmoidalis, and ground lamella. Independent variables were osteotomy site, age, gender, indication for surgery, and side. Corresponding cadaver data were analyzed for the independent variables of osteotomy site, side, and gender and then compared with the live patient data. Mean osteotomy force in live patients was 9.6 N (95% CI, 8.9–10.4 N). Mean osteotomy force in the cadaver heads was 6.4 N (95% CI, 5.7–7.0 N). Ethmoid osteotomy of live patients required 3.2 N (95% CI, 2.1–4.3 N) more force than the cadaver heads (p = 0.0001). This relationship was statistically significant at the bulla ethmoidalis (p = 0.002) and the ground lamella (p = 0.0001) but not at the uncinate (p = 0.068). Osteotomy in female live subjects required 1.6 N (95% CI, 0.1–3.1 N) more force than male live subjects (p = 0.03). Cadaver tissue may underestimate the mean osteotomy force required in osteotomy of living ethmoid sinus lamellae by a factor of 1.5 times. Caution may be required in extrapolating force estimates from cadaver tissue to those required in living patients.

Design, kinematic optimization, and evaluation of a teleoperated system for middle ear microsurgery

Middle ear surgery involves the smallest and the most fragile bones of the human body. Since microsurgical gestures and a submillimetric precision are required in these procedures, the outcome can be potentially improved by robotic assistance. Today, there is no commercially available device in this field. Here, we describe a method to design a teleoperated assistance robotic system dedicated to the middle ear surgery. Determination of design specifications, the kinematic structure, and its optimization are detailed. The robot-surgeon interface and the command modes are provided. Finally, the system is evaluated by realistic tasks in experimental dedicated settings and in human temporal bone specimens.

Stapedectomy in sheep: an animal model for surgical training

HYPOTHESIS AND BACKGROUND

Stapedectomy is a surgical technique that requires progressive training. The external and middle ear of sheep have a close resemblance to the human and have been previously used as surgical training models. In our project we describe the anatomy of the middle and external ear in sheep focusing on surgical landmarks and technique in order to determine whether the sheep's ear is an adequate model for stapedectomy training.

MATERIALS AND METHODS

We reviewed the literature on sheep anatomy and use of sheep as an otologic surgical model. Macroscopic sections as well as temporal bone computed tomography were obtained. Stapedectomy was performed on 40 sheep, using 4 mm platinum piston prosthesis, by first year residents.

RESULTS

Most of the structures in the sheep's middle ear are similar to those in humans although their size is about two thirds smaller. Incus long process is shorter, thicker, and closer to the malleus body, making the piston insertion and adjustment more difficult. The median surgical time of stapedectomy was reduced from 70 (52.5-100.3) minutes to 39.5 (35.5-48) minutes after completing training. There was also a reduction in rate of complications (flap disruption, incus dislocation, and footplate mobilization).

CONCLUSION

Sheep ears constitute a cheap, easy to obtain and anatomically adequate model for stapedectomy training.

Determination of the curling behavior of a preformed cochlear implant electrode array

PURPOSE

Accurate insertion of a cochlear implant electrode array into the cochlea's helical shape is a crucial step for residual hearing preservation. In image-guided surgery, especially using an automated insertion tool, the overall accuracy of the operative procedure can be improved by adapting the electrode array's intracochlear movement to the individual cochlear shape.

METHODS

The curling characteristic of a commercially available state-of-the-art preformed electrode array (Cochlear Ltd. Contour Advance(TM) Electrode Array) was determined using an image-processing algorithm to detect its shape in series of images. An automatic image-processing procedure was developed using Matlab and the Image Processing Toolbox (MathWorks, Natick, Massachusetts, USA) to determine the complete curvature of the electrode array by identifying the 22 platinum contacts of the electrode. A logarithmic spiral was used for a comprehensive mathematical description of the shape of the electrode array. A fitting algorithm for nonlinear least-squares problems was used to provide a complete mathematical description of the electrode array. The system was tested for curling behavior as a function of stylet extraction using nine Contour Advance Research Electrodes (RE) and additionally for nine Contour Advance Practice Electrodes (PE).

RESULTS

All arrays show a typical pattern of curling with adequate predictability after the first 2 or 3 millimeters of stylet extraction. Although non-negligible variations in the overall curling behavior were detected, the electrode arrays show a characteristic movement due to the stylet extraction and only vary minimally after this initial phase.

CONCLUSION

These results indicate that the risk of intracochlear trauma can be reduced if the specific curling behavior of the electrode carrier is incorporated into the insertion algorithm. Furthermore, the determination of the curling behavior is an essential step in computer-aided cochlear implant electrode development. Experimental data are required for accurate evaluation of the simulation model.

Automatic identification of otological drilling faults: an intelligent recognition algorithm

BACKGROUND

This article presents an intelligent recognition algorithm that can recognize milling states of the otological drill by fusing multi-sensor information.

METHODS

An otological drill was modified by the addition of sensors. The algorithm was designed according to features of the milling process and is composed of a characteristic curve, an adaptive filter and a rule base. The characteristic curve can weaken the impact of the unstable normal milling process and reserve the features of drilling faults. The adaptive filter is capable of suppressing interference in the characteristic curve by fusing multi-sensor information. The rule base can identify drilling faults through the filtering result data.

RESULTS

The experiments were repeated on fresh porcine scapulas, including normal milling and two drilling faults. The algorithm has high rates of identification.

CONCLUSIONS

This study shows that the intelligent recognition algorithm can identify drilling faults under interference conditions.

An automated insertion tool for cochlear implants: another step towards atraumatic cochlear implant surgery

PURPOSE

Atraumatic electrode insertion has been identified to be a crucial step for the preservation of residual hearing abilities, which allows hybrid electro-acoustic stimulation (EAS). The authors propose a tool for automation of the insertion process to achieve this.

METHODS

General benefits as well as concept and design of an automated insertion tool are presented. Thirty insertions of Nucleus 24 Contour Advance Practice Electrodes in an artificial scala tympani model as well as 20 insertions in a human cochlea specimen were performed using the tool, implementing the AOS technique. For both studies, the achieved insertion depth angle was evaluated by photographic or X-ray documentation.

RESULTS

The mean achieved insertion depth angle was 410 degrees for the lubricated model and 330 degrees for the human cochlea specimen.

CONCLUSION

The automated insertion tool has proven its capability to perform electrode insertions with final insertion depth angles within the target range of a standard cochlear implant surgery. Additionally, to the knowledge of the authors, it represents the only possibility to automatically insert cochlear implant electrodes via minimally invasive approaches.