Screening of factors influencing catheter rotation of a vascular interventional surgical robot using design of experiment approach.

Over the past decades, Vascular Interventional Surgery Robots (VISR) have been developed to address the risks associated with X-rays used in minimally invasive vascular surgery procedures. Manipulation of over-the-wire catheters is necessary to perform complex surgery but requires high forces on the robot's end effector during rotational movements. The VISR under study mimics the physician's fingers by rolling the catheter between two planar surfaces to rotate it. In this study, an experimental set-up is used to replicate this grasping method, also used in other VISR [1, 2]. The parameters of the gripping surfaces are investigated to maximise the torque delivered to the catheter and minimise the forces required at the robot's end-effector. The implemented design of experiment (DOE) demonstrated that large and soft gripping surfaces could achieve this compromise. By adjusting these parameters, sufficient torque can be achieved on the catheter.

Effect of embedded dexamethasone in cochlear implant array on insertion forces in an artificial model of scala tympani.

HYPOTHESIS: Loading otoprotective drug into cochlear implant might change its mechanical properties, thus compromising atraumatic insertion. This study evaluated the effect of incorporation of dexamethasone (DXM) in the silicone of cochlear implant arrays on insertion forces. BACKGROUND: Local administration of DXM with embedded array can potentially reduce inflammation and fibrosis after cochlear implantation procedure to improve hearing preservation and reduce long-term impedances. METHODS: Four models of arrays have been tested: 0.5-mm distal diameter array (n = 5) used as a control, drug-free 0.4-mm distal diameter array (n = 5), 0.4-mm distal diameter array with 1% eluded DXM silicone (n = 5), and 0.4-mm distal diameter array with 10% eluded DXM silicone (n = 5). Via a motorized insertion bench, each array has been inserted into an artificial scala tympani model. The forces were recorded by a 6-axis force sensor. Each array was tested seven times for a total number of 140 insertions. RESULTS: During the first 10-mm insertion, no difference between the four models was observed. From 10- to 24-mm insertion, the 0.5-mm distal diameter array presented higher insertion forces than the drug-free 0.4-mm distal diameter arrays, with or without DXM. Friction forces for drug-free 0.4-mm distal diameter array and 0.4-mm distal diameter DXM eluded arrays were similar on all insertion lengths. CONCLUSION: Incorporation of DXM in silicone for cochlear implant design does not change electrode array insertion forces. It does not raise the risk of trauma during array insertion, making it suitable for long-term in situ administration to the cochlea.

Definition of metrics to evaluate cochlear array insertion forces performed with forceps, insertion tool, or motorized tool in temporal bone specimens.

INTRODUCTION: In order to achieve a minimal trauma to the inner ear structures during array insertion, it would be suitable to control insertion forces. The aim of this work was to compare the insertion forces of an array insertion into anatomical specimens with three different insertion techniques: with forceps, with a commercial tool, and with a motorized tool. MATERIALS AND METHODS: Temporal bones have been mounted on a 6-axis force sensor to record insertion forces. Each temporal bone has been inserted, with a lateral wall electrode array, in random order, with each of the 3 techniques. RESULTS: Forceps manual and commercial tool insertions generated multiple jerks during whole length insertion related to fits and starts. On the contrary, insertion force with the motorized tool only rose at the end of the insertion. Overall force momentum was 1.16 ± 0.505 N (mean ± SD, n = 10), 1.337 ± 0.408 N (n = 8), and 1.573 ± 0.764 N (n = 8) for manual insertion with forceps and commercial and motorized tools, respectively. CONCLUSION: Considering force momentum, no difference between the three techniques was observed. Nevertheless, a more predictable force profile could be observed with the motorized tool with a smoother rise of insertion forces.

Middle-ear microsurgery simulation to improve new robotic procedures.

Otological microsurgery is delicate and requires high dexterity in bad ergonomic conditions. To assist surgeons in these indications, a teleoperated system, called RobOtol, is developed. This robot enhances gesture accuracy and handiness and allows exploration of new procedures for middle ear surgery. To plan new procedures that exploit the capacities given by the robot, a surgical simulator is developed. The simulation reproduces with high fidelity the behavior of the anatomical structures and can also be used as a training tool for an easier control of the robot for surgeons. In the paper, we introduce the middle ear surgical simulation and then we perform virtually two challenging procedures with the robot. We show how interactive simulation can assist in analyzing the benefits of robotics in the case of complex manipulations or ergonomics studies and allow the development of innovative surgical procedures. New robot-based microsurgical procedures are investigated. The improvement offered by RobOtol is also evaluated and discussed.

Validation method of a middle ear mechanical model to develop a surgical simulator.

Ossicular surgery requires a high dexterity for the manipulation of the fragile and small middle ear components. Currently, the only efficient technique for training residents in otological surgery is through the use of temporal bone specimens, where any existing surgical simulator does not provide useful feedback. The objective of this study was to develop a finite-element model of the human ossicular chain dedicated to surgical simulation and to propose a method to evaluate its behavior. A model was developed based on human middle ear micromagnetic resonance imaging. The mechanical parameters were determined according to published data. To assess its performance, the middle ear transfer function was analyzed. The robustness of our model and the influence of different middle ear components were also evaluated at low frequency by static force pressure simulations. The mechanical behavior of our model in nominal and pathological conditions was in good agreement with published human temporal bone measurements. We showed that the cochlea influences the transfer function only at high frequency and could be omitted from a surgical simulator. In addition, surgeons were able to manipulate the validated middle ear model with a real-time haptic feedback. The computational efficiency of our approach allowed real-time interactions, making it suitable for use in a training simulator.

Registration of a validated mechanical atlas of middle ear for surgical simulation.

This paper is centered on the development of a new training and rehearsal simulation system for middle ear surgery. First, we have developed and validated a mechanical atlas based on finite element method of the human middle ear. The atlas is based on a microMRI. Its mechanical behavior computed in real-time has been successfully validated. In addition, we propose a method for the registration of the mechanical atlas on patient imagery. The simulation can be used for a rehearsal surgery with the geometrical anatomy of a given patient and with mechanical data that are validated. Moreover, this process does not necessitate a complete re-built of the model.

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.

Friction force measurement during cochlear implant insertion: application to a force-controlled insertion tool design.

HYPOTHESIS: The aim of the study was to evaluate force profiles during array insertion in human cochlea specimens and to evaluate a mechatronic inserter using a 1-axis force sensor. BACKGROUND: Today, the surgical challenge in cochlear implantation is the preservation of the anatomic structures and the residual hearing. In routine practice, the electrode array is inserted manually with a limited sensitive feedback. MATERIALS AND METHODS: Hifocus 1J electrode arrays were studied. The bench test comprised a mechatronic inserter combined to a 1-axis force sensor between the inserter and the base of the array and a 6-axis force sensor beneath the cochlea model. Influence of insertion tube material, speed (0.15, 0.5, and 1.5 mm/s) and lubricant on frictions forces were studied (no-load). Different models were subsequently evaluated: epoxy scala tympani model and temporal bones. RESULTS: Frictions forces were lower in the plastic tube compared with those in the metal tube (0.09 ± 0.028 versus 0.14 ± 0.034 at 0.5 mm/s, p < 0.001) and with the use of hyaluronic acid gel. Speed did not influence frictions forces in our study. Insertion force profiles provided by the 1- and 6-axis force sensors were similar when friction forces inside the insertion tool (no-load measurements) were subtracted from the 1-axis sensor data in the epoxy and temporal bone models (mean error, 0.01 ± 0.001 N). CONCLUSION: Using a sensor included in the inserter, we were able to measure array insertion forces. This tool can be potentially used to provide real-time information to the surgeon during the procedure.

Cochlear implant insertion forces in microdissected human cochlea to evaluate a prototype array.

Cochlear implant array insertion forces are potentially related to cochlear trauma. We compared these forces between a standard (Digisonic SP; Neurelec, Vallauris, France) and an array prototype (Neurelec) with a smaller diameter. The arrays were inserted by a mechatronic tool in 23 dissected human cochlea specimens exposing the basilar membrane. The array progression under the basilar membrane was filmed together with dynamic force measurements. Insertion force profiles and depth of insertion were compared. The recordings showed lower insertion forces beyond 270° of insertion and deeper insertions with the thin prototype array. This will potentially allow larger cochlear coverage with less trauma.

From conception to application of a tele-operated assistance robot for middle ear surgery.

The authors' goal was to design and evaluate a robot dedicated to middle ear surgery. Specifications for dimensions, forces, and kinematics were collected, based on the otosclerosis procedure. The robot structure has a compact geometry with 3 linear and 3 rotatory motors. It is remotely piloted via a robot-surgeon interface under operative microscope. Ability to reach anatomical targets, to perform stapedectomy, and to place prosthesis in a model of stapedotomy was evaluated by 6 surgeons. Multiple anatomical targets in the middle ear could be successfully reached without damaging surrounding structures. The robot could be used under operative microscope with minimal visual field impairment or jointly with a 4-mm endoscope through the external auditory canal to perform stapedectomy in temporal bone specimens. Prosthesis could be inserted in the stapedotomy model. The assistance robot is the first prototype with 6 degrees of freedom, a kinematic structure, and dimensions optimized for tele-operated middle ear surgery.

Minimally invasive computer-assisted approach for cochlear implantation: a human temporal bone study.

Computer-assisted navigation systems can now potentially guide the surgeon to the cochlea with a trajectory avoiding the facial nerve through a keyhole approach. Five temporal bone specimens, with 4 titanium screws placed in the mastoid cortex, were studied. Preoperative computed tomographic scan images were loaded on an electromagnetic computer-assisted surgery (CAS) system (Digipointeur, Collin, Bagneux, France). A drill was connected to the CAS to monitor its progression continuously. A conical approach passing through the facial recess and ending in the scala tympani was performed. A 0.5-mm wire was inserted into the cochlea. The keyhole approach was technically feasible in all cases. No facial nerve injury was observed on imaging and dissection control. The wire was positioned in the scala tympani and the position accuracy of the CAS was <0.76 mm on the target in all cases. The CAS system with fiducial markers yielded sufficient precision to allow a minimally invasive approach to the cochlea.