Insertion experiments of a biologically inspired microtextured and multi-part probe based on reciprocal motion.

While there have been significant advances in minimally invasive surgical instrumentation, the majority of tools still rely on a push from the back to aid insertion into the tissue, whether the process is manual or servo assisted. In this work, a novel approach to tool insertion is proposed which is based on the concept of a multi-part probe with at least three interlocking segments. By means of a sequential insertion process, where each segment is pushed further into the tissue while stabilized by the remaining stationary parts, the multi-part probe concept is shown to successfully "insinuate itself" within a synthetic soft tissue specimen without the need for an overall forward push. The presence of an anisotropic microtextured outer probe surface is also shown to affect the overall speed of insertion and can thus be used to optimize the interaction forces at the probe-tissue interface. A measured reduction in the force transferred to the back of the specimen also suggests that this approach to tool insertion may result in reduced tissue disruption, a result which could lead to less tissue damage and a reduction in target displacement.

Development and validation of a numerical model for cross-section optimization of a multi-part probe for soft tissue intervention.

The popularity of minimally invasive surgical procedures is driving the development of novel, safer and more accurate surgical tools. In this context a multi-part probe for soft tissue surgery is being developed in the Mechatronics in Medicine Laboratory at Imperial College, London. This study reports an optimization procedure using finite element methods, for the identification of an interlock geometry able to limit the separation of the segments composing the multi-part probe. An optimal geometry was obtained and the corresponding three-dimensional finite element model validated experimentally. Simulation results are shown to be consistent with the physical experiments. The outcome of this study is an important step in the provision of a novel miniature steerable probe for surgery.

Active constraint control for image-guided robotic surgery.

The concept of active constraint control for image-guided robotic surgery is introduced, together with its benefits and a short outline of its history. The clinical use of active constraint control in orthopaedic surgery is discussed, together with the outcomes of a clinical trial for unicondylar knee replacement surgery. The evolution of the robotic design from large costly structures towards simpler, more cost-effective systems is also presented, leading to the design of the Acrobot 'Sculptor' system. A new approach to the achievement of robotic total knee replacement is also presented, in which a high-speed rotary cutter is used to slice through the bone to achieve a speedy resection. The control concept is presented, together with the results of trials on animal bones and a cadaver, showing that it is possible to remove large quantities of bone both quickly and accurately.

A review of medical robotics for minimally invasive soft tissue surgery.

This paper provides an overview of recent trends and developments in medical robotics for minimally invasive soft tissue surgery, with a view to highlight some of the issues posed and solutions proposed in the literature. The paper includes a thorough review of the literature, which focuses on soft tissue surgical robots developed and published in the last five years (between 2004 and 2008) in indexed journals and conference proceedings. Only surgical systems were considered; imaging and diagnostic devices were excluded from the review. The systems included in this paper are classified according to the following surgical specialties: neurosurgery; eye surgery and ear, nose, and throat (ENT); general, thoracic, and cardiac surgery; gastrointestinal and colorectal surgery; and urologic surgery. The systems are also cross-classified according to their engineering design and robotics technology, which is included in tabular form at the end of the paper. The review concludes with an overview of the field, along with some statistical considerations about the size, geographical spread, and impact of medical robotics for soft tissue surgery today.

Applying tactile sensing with piezoelectric materials for minimally invasive surgery and magnetic-resonance-guided interventions.

Medical technologies have undergone significant development to overcome the problems inherent in minimally invasive surgery such as inhibited manual dexterity, reduced visual information, and lack of direct touch feedback to make it easier for surgeons to operate. A minimally invasive tool incorporating haptic feedback is being developed to increase the effectiveness of diagnostic procedures by providing force feedback. Magnetic resonance imaging guidance is possible to allow tool localization; however, this engenders the requirement of magnetic resonance compatibility on the device. This paper describes the work done towards developing a sensing device using piezoelectric sensor elements to locate subsurface inclusions in soft substrates, with its magnetic resonance compatibility tested in a 1.5 T scanner. Results show that the position of a hard inclusion can be determined.

Lung respiratory rhythm and pattern generation in the bullfrog: role of neurokinin-1 and mu-opioid receptors.

Location of the lung respiratory rhythm generator (RRG) in the bullfrog brainstem was investigated by examining neurokinin-1 and mu-opioid receptor (NK1R, muOR) colocalization by immunohistochemistry and characterizing the role of these receptors in lung rhythm and episodic pattern generation. NK1R and muOR occurred in brainstems from all developmental stages. In juvenile bullfrogs a distinct area of colocalization was coincident with high-intensity fluorescent labeling of muOR; high-intensity labeling of muOR was not distinctly and consistently localized in tadpole brainstems. NK1R labeling intensity did not change with development. Similarity in colocalization is consistent with similarity in responses to substance P (SP, NK1R agonist) and DAMGO (muOR agonist) when bath applied to bullfrog brainstems of different developmental stages. In early stage tadpoles and juvenile bullfrogs, SP increased and DAMGO decreased lung burst frequency. In juvenile bullfrogs, SP increased lung burst frequency, episode frequency, but decreased number of lung bursts per episode and lung burst duration. In contrast, DAMGO decreased lung burst frequency and burst cycle frequency, episode frequency, and number of lung bursts per episode but increased all other lung burst parameters. Based on these results, we hypothesize that NK1R and muOR colocalization together with a metamorphosis-related increase in muOR intensity marks the location of the lung RRG but not necessarily the lung episodic pattern generator.

A magnetic-resonance-compatible limb-positioning device to facilitate magic angle experiments in vivo.

Owing to their highly ordered structure, tendons and cartilage appear with low signal intensity when imaged using magnetic resonance imaging (MRI) scanners. A significant increase in signal can be observed when these structures are oriented at 55 degrees (termed the magic angle) with respect to the static field B0. There is a clear clinical importance in exploiting this effect as part of the diagnosis of injury. Experimental studies of this phenomenon have been made harder by the practical difficulties associated with tissue positioning and orientation in the confined environment of closed-bore scanners. An MRI-compatible mechatronic system has been developed, which is capable of positioning a number of limbs to a desired orientation inside the scanner, to be used as a diagnostic and research tool. It is actuated with a novel pneumatic motor consisting of a heavily geared-down air turbine, presenting high torques and good accuracy. The system is shown to be magnetic resonance compatible and the results of preliminary trials using the device to image the Achilles tendon of human volunteers at different orientations are presented. An increase of four fold to thirteen fold in signal intensity can be observed at the magic angle.

Biologically inspired microtexturing: investigation into the surface topography of next-generation neurosurgical probes.

Minimally Invasive (MI) surgery represents the future of many types of medical intervention (keyhole neurosurgery, natural orifice trans-luminal endoscopic surgery, etc.). However, the shortcomings of today's surgical tools fuel the need for the development of next-generation 'smart instrumentation', which will be more accurate and safer for the patient. This paper presents the preliminary results of a biologically inspired microtexturing method, based on UV-lithography, and its application to MI neurosurgery. These results suggest that the size and geometry of the texture 'printed' on the outer surface of a neurosurgical probe clearly affect the insertion and extraction forces generated at the brain-probe interface. Thus, by carefully choosing an appropriate microtexture, unique insertion characteristics can be obtained, which can improve the performance of existing instruments (e.g. reducing slippage in permanent electrodes such as those used in deep brain stimulation) or enable the development of novel designs altogether.

Computer-assisted hip resurfacing surgery using the acrobot navigation system.

The authors have previously reported on the laboratory development of the Acrobot Navigation System for accurate computer-assisted hip resurfacing surgery. This paper describes the findings of using the system in the clinical setting and including the improvements that have been made to expedite the procedure. The aim of the present system is to allow accurate planning of the procedure and precise placement of the prosthesis in accordance with the plan, with a zero intraoperative time penalty in comparison to the standard non-navigated technique. At present the navigation system is undergoing final clinical evaluation prior to a clinical study designed to demonstrate the accuracy of outcome compared with the conventional technique. While full results are not yet available, this paper describes the techniques that will be used to evaluate accuracy by comparing pre-operative computed tomography (CT)-based plans with post-operative CT scans. Example qualitative clinical results are included based on visual comparison of the plan with post-operative X-rays.

Robotic control in knee joint replacement surgery.

A brief history of robotic systems in knee arthroplasty is provided. The place of autonomous robots is then discussed and compared to more recent 'hands-on' robotic systems that can be more cost effective. The case is made for robotic systems to have a clear justification, with improved benefits compared to those from cheaper navigation systems. A number of more recent, smaller, robot systems for knee arthroplasty are also described. A specific example is given of an active constraint medical robot, the ACROBOT system, used in a prospective randomized controlled trial of unicondylar robotic knee arthroplasty in which the robot was compared to conventional surgery. The results of the trial are presented together with a discussion of the need for measures of accuracy to be introduced so that the efficacy of the robotic surgery can be immediately identified, rather than have to wait for a number of years before long-term clinical improvements can be demonstrated.

Preoperative planning and intraoperative guidance for accurate computer-assisted minimally invasive hip resurfacing surgery.

Hip resurfacing is an alternative to total hip replacement (THR) and is particularly suitable for the younger, more active patient. However, it is a more demanding procedure. This paper describes a system that enables the surgeon to plan the surgery preoperatively with optimally sized and placed components, and then transfer this plan to an intraoperative system that registers computer models to the real patient and tracks surgical tools, allowing the surgeon to ensure that the bone is resected correctly and that the components are fitted in accordance with the plan. The paper describes a series of instruments used with the system which are locked to the bone. These instruments serve the dual purpose of soft tissue retraction and bone immobilization. The system will shortly be the subject of laboratory and clinical evaluation. Registration, a cornerstone of the tracked instrument system, has been tested, and accuracy measures are provided. Experimental results for the remainder of the system will be provided after clinical trials.

Brachytherapy--an example of a urological minimally invasive robotic procedure.

A review of the application of urological robots to the prostate is given, together with an examination of the conventional brachytherapy procedure for insertion of radioactive seeds to treat prostate cancer. The specification and design of a robotic system is provided, which can position a series of needles and radioactive pellets in accordance with a pre-operative plan. The needles can be withdrawn automatically, leaving the seeds in position.A separate motorised system is used to position a trans-rectal ultrasound (U/S) probe, which can be used to continually monitor the seed placement. The robot program can be updated intra-operatively if the U/S image shows this to be necessary. The demonstrator system has been demonstrated in-vitro using a variety of gel and animal tissue phantoms. The resulting robot performance shows this to be a viable approach.

A computer assisted surgical trainer for transurethral resection of the prostate.

PURPOSE: We developed a realistic and reusable computer assisted surgical training system for transurethral resection of the prostate. MATERIALS AND METHODS: A disposable prostate model is housed in a model abdomen. A software program that provides a 3-dimensional (D) illustration of the prostate model was developed. Resectoscope position with reference to the model is tracked by infrared emitting diodes attached to it, which in turn are monitored by an optical tracker. Movement of the loop in relation to the resectoscope is measured by a potentiometer attached to the working element. RESULTS: Resectoscope position was shown on the monitor superimposed on a 3-D image of the prostate model in real time. A 2-D image showed the amount of tissue resected and the proximity of the loop to the capsule. A series of thumbnail images were shown and the highlighted image represented the current position of the resectoscope. It is intended that this system should be interactive, providing continuous feedback on the progress of resection and acting as an interactive training aid. During the course of validating the system several problems were noted, mainly with model movement and permanent deformation of the model during resection. CONCLUSIONS: This system can exist as a stand-alone training aid after the problems have been addressed. The potential application of an in vivo system for routine transurethral prostate resection has great implications for training and quality control.

A multiple focused probe approach for high intensity focused ultrasound based surgery.

To produce deep-seated surgical lesions using ultrasound requires high power and intensity levels at the target sites. Conventionally, large transducers are used which require big apertures and so are generally suitable only for extra-corporeal access. Such transducers also result in strong off-focus maxima, where the resulting hot spots can destroy normal tissue whilst deep-seated large tissue volumes are being ablated. This paper describes a new approach in which it is proposed that multiple probes are used simultaneously, each at a relatively low power, to result in an overlapping focused region of high temperature without strong off-focus hot spots. Robotic techniques could be used to move the individual probes in coordination to sweep out the desired region of tissue ablation. Simulation and planning are the key to quality prediction for high intensity focused ultrasound (HIFU). Simplified two-dimensional and three-dimensional models of HIFU probes have been developed to study the characteristics of various multi-probe configurations. Preliminary simulation results show that the multi-probe system can be arranged successfully to minimise off-focus hot spots. Experimental results are presented which validate the modality and confirm this positive finding. Further prediction studies and planning will be necessary to achieve the most appropriate desired treatment, by varying the pulse duration and spacing.

The first clinical application of a "hands-on" robotic knee surgery system.

The performance of a novel "hands-on" robotic system for total knee replacement (TKR) surgery is evaluated. An integrated robotic system for accurately machining the bone surfaces in TKR surgery is described. Details of the system, comprising an "active constraint" robot, called Acrobot, a "gross positioning" robot, and patient clamps, are provided. The intraoperative protocol and the preoperative, CT-based, planning system are also described. A number of anatomical registration and cutting trials, using plastic bones, are described, followed by results from two preliminary clinical trials, which demonstrate the accuracy achieved in the anatomical registration. Finally, the first clinical trial is described, in which the results of the anatomical registration and bone cutting are seen to be of high quality. The Acrobot system has been successfully used to accurately register and cut the knee bones in TKR surgery. This demonstrates the great potential of a "hands-on" robot for improving accuracy and increasing safety in surgery.

A robotic system for blood sampling.

A robotic system to take blood samples autonomously from the forearm is presented and preliminary results are discussed which demonstrate its feasibility. Force/position profiles, while pressing a flat-headed probe against the surface of the skin, enable the determination of a vein's location to within 1 mm on a phantom. When a needle is inserted, the characteristic force/position profile, on puncturing the vein wall, is distinctive enough to implement automatic needle withdrawal to prevent overshoot. Future developments of the project are presented that provide both an autonomous blood sampling robot and a force-feedback surgical trainer.

Automated prostate recognition: a key process for clinically effective robotic prostatectomy.

Clinical trials of PROBOT, a robotic system for prostate surgery, have shown that robotic surgery of soft tissue can be successful. Monitoring of the progress of the resection has shown to be a necessary feature of an effective robotic system for prostate surgery. It should provide the surgeon with a reliable method of assessing the cavity during resection. An automatic system for intraoperative monitoring of the progress of the resection during robotic prostatectomy consists of two subsystems: real-time intraoperative imaging of the prostate and automatic identification of the contour of the gland on each image. The development of a fully automatic scheme for prostate recognition on transurethral ultrasound scans is reported. A genetic algorithm has been developed to automatically adjust a model of the prostate boundary until an optimum fit to the prostate in a given image is obtained. An analysis of its performance on 22 different ultrasound images showed an average error of 6.21 mm. Use of a genetic algorithm and a constrained prostate model have shown to be a robust way to automatically identify the prostate in ultrasound images. The scheme is able to produce approximate prostate boundaries, without any human intervention, on ultrasound scans of varying quality. In addition to soft tissue robotic surgery, the genetic algorithm technique is also applicable to a wide range of computer assisted surgical techniques.

A computer-assisted training/monitoring system for TURP structure and design.

A generic framework for a computer-assisted system for both soft tissue endoscopic surgery and surgical training is being researched and developed. The concept demonstrator is a specific system for transurethral prostatic resection (TURP). The main novelty of the research is that it is not confined to an in vitro trainer system. An in vivo monitoring version of the system, for use in the operating theater, is also being researched. This paper presents the framework's structure and design using the United Modeling Language. It also discusses and justifies the underlying information technologies chosen to implement this approach. Object-oriented concepts and well-proven mathematical tools have been adopted as the foundation of this research and development. The rationale for having chosen such tools is presented. The objectives are to arrive at a system which is modular, general, and reusable.

Education of women about the prevention of preterm birth.

OBJECTIVES: To describe: 1) The education of pregnant women by health care professionals about the prevention of preterm birth; and 2) professionals' views about future initiatives. BACKGROUND: A population survey of health professionals was conducted in Eastern Ontario. The response rate was 73% (608/835). RESULTS: Education materials for women receiving prenatal care about the prevention of preterm birth were available from 10% (12/115) of family physicians, 40% (23/58) of obstetricians, 19% (57/306) of labour room nurses and 76% (94/124) of the prenatal teachers. Only one third of physicians routinely discussed the signs and symptoms of preterm labour prior to 20 weeks. Practitioners' future priorities were smoking cessation programs for pregnant women and increased attendance at early prenatal classes. CONCLUSIONS: Most women are not being educated by anyone in the health care team about the prevention of preterm birth. There is a need for multidisciplinary guidelines about the timing and type of information for women about risk reduction and the early identification and treatment of preterm labour.