A smart micro-drill for cochleostomy formation: a comparison of cochlear disturbances with manual drilling and a human trial.

BACKGROUND: Cochleostomy formation is a key stage of the cochlear implantation procedure. Minimizing the trauma sustained by the cochlea during this step is thought to be a critical feature in hearing preservation cochlear implantation. The aim of this paper is firstly, to assess the cochlea disturbances during manual and robotic cochleostomy formation. Secondly, to determine whether the use of a smart micro-drill is feasible during human cochlear implantation. MATERIALS AND METHODS: The disturbances within the cochlea during cochleostomy formation were analysed in a porcine specimen by creating a third window cochleostomy, preserving the underlying endosteal membrane, on the anterior aspect of the basal turn of the cochlea. A laser vibrometer was aimed at this third window, to assess its movement while a traditional cochleostomy was performed. Six cochleostomies were performed in total, three manually and three with a smart micro-drill. The mean and peak membrane movement was calculated for both manual and smart micro-drill arms, to represent the disturbances sustained within cochlea during cochleostomy formation. The smart micro-drill was further used to perform live human robotic cochleostomies on three adult patients who met the National Institute of Health and Clinical Excellence criteria for undergoing cochlear implantation. RESULTS: In the porcine trial, the smart micro-drill preserved the endosteal membrane in all three cases. The velocity of movement of the endosteal membrane during manual cochleostomy is approximately 20 times higher on average and 100 times greater in peak velocity, than for robotic cochleostomy. The robot was safely utilized in theatre in all three cases and successfully created a bony cochleostomy while preserving the underlying endosteal membrane. CONCLUSIONS: Our experiments have revealed that controlling the force of drilling during cochleostomy formation and opening the endosteal membrane with a pick will minimize the trauma sustained by the cochlea by a factor of 20. Additionally, the smart micro-drill can safely perform a bony cochleostomy in humans under operative conditions and preserve the integrity of the underlying endosteal membrane.

Discriminating contact in lumen with a moving flexible digit using fibre Bragg grating sensing elements.

Minimal access procedures in surgery offer benefits of reduced patient recovery time and less pain, yet for the surgeon the task is more complex, as both tactile and visual perception of the working site is reduced. In this paper, experimental evidence of the performance of a novel sensing system embedded in an actuated flexible digit element is presented. The digit represents a steerable tip element of devices such as endoscopes and laparoscopes. This solution is able to discriminate types of contact and tissue interaction, and to feed back this information with the shape of the flexible digit. As an alternative to this information, force level, force distribution, and other quantifiable descriptors can also be evaluated. These can be used to aid perception in processes such as navigation and investigation of tissues through palpation. The solution is pragmatic, and by virtue of its efficient mechanical construction and a polymer construction, it offers opportunities for a disposable element with suitability for magnetic resonance imaging (MRI) and other scanning environments. By using only four photonics sensing elements, full perception of tissue contact and the shape of the actuated digit can be described in the feedback of this information. The distributive sensory method applied to the sensory signals relies on the coupled values of the sensory data transients of the four deployed sensing elements to discriminate tissue interaction directly in near real time.

Quantifying sway through surface deflection patterns: a novel approach using distributive tactile sensing.

This paper describes an experiment that extends the distributive sensing approach to identify the three-dimensional location of an object in constant motion. Distributive sensing has previously been successful in the identification of size and location of statically placed objects. Here, a novel system is developed to measure balance or sway in patients. The experimental set-up consisted of a pendulum structure positioned on a supported steel plate. Three low-cost deflection sensors were positioned under the plate with the resulting signals used as inputs to a neural network implemented on a field-programmable gate array. The results show that the embedded system can accurately track the pendulum position in real time with a mean tracking error of around 6 per cent in all three dimensions. This evidence indicates that the technique is sufficiently sensitive and could be implemented in a pragmatic configuration for discriminating between balance and sway.

A smart sensing platform for the classification of ambulatory patterns.

This paper describes an innovative sensing approach allowing capture, discrimination, and classification of transients automatically in gait. A walking platform is described, which offers an alternative design to that of standard force plates with advantages that include mechanical simplicity and less restriction on dimensions. The scope of the work is to investigate as an experiment the sensitivity of the distributive tactile sensing method with the potential to address flexibility on gait assessment, including patient targeting and the extension to a variety of ambulatory applications. Using infrared sensors to measure plate deflection, gait patterns are compared with stored templates using a pattern recognition algorithm. This information is input into a neural network to classify normal and affected walking events, with a classification accuracy of just under 90 per cent achieved. The system developed has potential applications in gait analysis and rehabilitation, whereby it can be used as a tool for early diagnosis of walking disorders or to determine changes between pre- and post-operative gait.

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

OBJECTIVE: To produce an autonomous drilling robot capable of performing a bony cochleostomy whilst minimising the damage to the underlying cochlear endosteum. DESIGN: In this laboratory based study, a robotic drill was designed to measure the changes in force and torque experienced by the tool point during the drilling process. This information is used to predict the point of breakthrough and stop the drill prior to damaging the underlying endosteal membrane. SETTING: Aston University. PARTICIPANTS: Five porcine cochleas. MAIN OUTCOMES MEASURES: An assessment was made of whether a successful bony cochleostomy was performed, the integrity of endosteal membrane was then assessed. RESULTS: The autonomous surgical robotic drill successfully performed a bony cochleostomy and stopped without damaging the endosteal membrane in all five cases. CONCLUSIONS: The autonomous surgical robotic drill can perform a cochleostomy whilst minimising the trauma to the endosteal membrane. The system allows information about the state of the drilling process to be derived using force and torque data from the tool point. This information can be used to effectively predict drill breakthrough and implement a control strategy to minimise drill penetration beyond the far surface.

A surgical robot for cochleostomy.

In this paper a robotic micro-drilling technique for surgery is described. The device has been deployed in cochleostomy, a precise micro-surgical procedure where the critical stage of controlling penetration of the outer bone tissue of the cochlea is achieved without penetration of the endosteal membrane at the medial surface. The significance of the work is that the device navigates by using transients of the reactive drilling forces to discriminate cutting conditions, state of tissue and the detection of the medial surface before drill break-out occurs. This is the first autonomous surgical robot to use this technique in real-time as a navigation function in the operating room and unlike other fully autonomous surgical robotic processes it is carried out without the use pre-operative data to control the motion of the tool. To control tool points in flexible tissues requires self-referencing to the tissue position in real time. There is also the need to discriminate deflections of the tissue, tissue interface, involuntary patients/tissue movement and indeed movement induced by the drill itself, which require different strategies to be selected for control. As a result of the design of the final system, the break-out process of the drill can either controlled to the required level of protrusion through the flexible interface or can be avoided altogether, with the drill bit at the medial surface. This enables, for the first time, the control of fine penetration with such great precision.

ENT challenges at the small scale.

BACKGROUND: In this paper we consider two relatively frequently performed operations in the field of ear, nose and throat (ENT) surgery and consider how they could be improved by using robotic applications. We consider currently available robots and propose theoretical robotic solutions. METHODS: The application of robotic systems for both cochlear implantation and endoscopic sinus surgery was considered. Currently available robotic systems were reviewed and those with potential use in ENT surgery were identified. For aspects of operations where there is no available technology, hypotheses are presented on how robots could help. RESULTS: Three robotic systems were identified with potential usage in ENT: the Pathfinder neurosurgical robot, the Acrobot knee replacement system and the autonomous smart drill for drilling a cochleostomy. CONCLUSIONS: The challenge for the future of ENT is being able to perform tasks beyond the level of human perception and abilities. The examples presented here demonstrate that microtechnologies could be used to reduce complications, decrease operating time and improve clinical results.

A flexible digit with tactile feedback for invasive clinical applications.

This paper describes research on measurement of tactile sense using a flexible digit appropriate to endoscopy and minimal access surgery. It is envisaged that the sensing method will facilitate the navigation of flexible invasive devices, such as endoscopes, and also aid diagnosis using tactile perception as well as visual observation. The proposed master-slave digit system incorporates the application of the distributive sensing method applied to tactile sensing in order to discriminate different contact conditions of the flexible digit. The paper concentrates on the description of the application of this method and places this in the context of the user and the integrated system. The approach to sensing is able to discriminate the position, magnitude, distributed profile and width of the applied contacting load by using only four sensing points. Values to describe these parameters are evaluated to an accuracy greater than 93 per cent.

The potential of robotic technology applied to meet requirements for tools to support microsurgery and cellular surgery.

Microsurgery and processes involving cell manipulation or cell surgery are clinical practices where the operator works at or beyond the threshold of human dexterity. Current tools available are conventional in their design, and this limits consistency and the level of reliability and achievement. Surgical robotic devices have been explored to improve precision in minimal access surgical procedures to augment control of tool points in tissues, and have enabled feedback of sensory data from which the operator is able to deduce information on the tool at the working site. In this paper, relevant technologies are described that can be harnessed to improve perception of tool point interaction with tissues at the working site and to improve tool control at the small scale required in clinical practice for microsurgery and for cell surgery.

Human perception of haptic information in minimal access surgery tools for use in simulation.

This paper describes research on human perception of haptic information in minimal access surgery (MAS) instruments, for use in a MAS simulator. Understanding the thresholds of human perception is important in determining which haptic information must be provided for realistic feedback and which information can be ignored without compromising the immersive quality of the simulator. Initially this research has determined the limits of perception for non-continuous change of force amplitude and frequency in a scissors-grasping position.

Schemes for the identification of tissue types and boundaries at the tool point for surgical needles.

Precise control of automated invasive surgical tools requires real-time identification of tissue types and their deformation. At the focus of this paper is the epidural puncture, for which it is shown that the tissue type and deformation can respectively be determined from laser-based spectroscopy and the change in force required to push the needle through the various tissues. Studies have shown that physiological variations from one patient to another are too great to allow absolute values to be reliably used to indicate the position of the needle tip. However, the pattern of force variation during penetration is shown to be similar between specimens. Interpretation of this information in conjunction with spectroscopic techniques can be used to discriminate between tissues and tissue structure at the needle tip. This paper describes results from an investigation on automatic techniques for interpreting the type and deformation of tissues under tool action.

Estimation of the stapes-bone thickness in the stapedotomy surgical procedure using a machine-learning technique.

Stapedotomy is a surgical procedure aimed at the treatment of hearing impairment due to otosclerosis. The treatment consists of drilling a hole through the stapes bone in the inner ear in order to insert a prosthesis. Safety precautions require knowledge of the nonmeasurable stapes thickness. The technical goal herein has been the design of high-level controls for an intelligent mechatronics drilling tool in order to enable the estimation of stapes thickness from measurable drilling data. The goal has been met by learning a map between drilling features, hence no model of the physical system has been necessary. Learning has been achieved as explained in this paper by a scheme, namely the d-sigma Fuzzy Lattice Neurocomputing (d sigma-FLN) scheme for classification, within the framework of fuzzy lattices. The successful application of the d sigma-FLN scheme is demonstrated in estimating the thickness of a stapes bone "on-line" using drilling data obtained experimentally in the laboratory.

A technique for measuring contact force distribution in minimally invasive surgical procedures.

This paper investigates new methods for measuring forces and tactile sense as a contribution towards relaying the sense of touch to the surgeon. The approach used is to determine a distribution of contact force using a small number of sensory outputs to detect the bending of a surface of known behaviour. Software algorithms have been produced to interpret the contacting force from sensory data, and have achieved a bandwidth of 30 Hz and an accuracy of 2 per cent. The sensor construction is of sufficiently low cost to produce a disposable unit and uses materials that are compatible with the invasive working environment.

Simulation of resistance forces acting on surgical needles.

High precision in the manual control of needles and biopsy probes in medical treatment requires high skill and dexterity levels. In anaesthesia, force sensation is an important feedback mechanism, and the practitioner needs to refresh or develop skills to improve on the interpretation of needle progress towards the target site. This paper describes an experimental tactile force simulator for uniaxial needle action for which the force resisting progress of the needle is derived from measured data. As an example, the approach taken to develop the simulation of the insertion of epidural needles is described. Adaptation to other procedures would be possible by adopting new reference models based on appropriate measured force data.

An automatic technique for micro-drilling a stapedotomy in the flexible stapes footplate.

This paper describes a technique for controlling the drill bit breakthrough during low-speed micro-drilling of a flexible bone element. The research reported focuses on the penetration of the stapes footplate at the boundary of the middle and inner ear where there is a need to minimize the penetration of the drill bit through the medial surface. The bone is of unknown thickness and compliance, and the efficiency of cutting is variable between specimens. An automated system is presented that is able to determine these unknowns, to detect the onset of breakthrough and to control drill protrusion beyond the medial surface. The methods used to determine and control the level of protrusion on breakthrough are described. It is reported that the drill bit protrusion beyond the medial surface is achieved to within 0.02 mm of the ideal position.