Louise Moody

Passive haptics in a knee arthroscopy simulator: is it valid for core skills training?

Previous investigation of a cost-effective virtual reality arthroscopic training system, the Sheffield Knee Arthroscopy Training System (SKATS), indicated the desirability of including haptic feedback. A formal task analysis con firmed the importance of knee positioning as a core skill for trainees learning to navigate the knee arthroscopically. The system cost and existing limb interface, which permits knee positioning, would be compromised by the addition of commercial active haptic devices available currently. The validation results obtained when passive haptic feedback (resistance provided by physical structures) is provided indicate that SKATS has construct, predictive and face va lidity for navigation and triangulation training. When tested using SKATS, experienced surgeons (n = 11) performed significantly faster, located significantly more pathologies, and showed significantly shorter arthroscope path lengths than a less experienced surgeon cohort (n = 12). After SKATS training sessions, novices (n = 3) showed significant improvements in: task completion time, shorter arthroscope path lengths, shorter probe path lengths, and fewer arthroscope tip contacts. Main improvements occurred after the first two practice sessions, indicating rapid familiarization and a training effect. Feedback from questionnaires completed by orthopaedic surgeons indicates that the system has face validity for its remit of basic arthroscopic training.

Objective surgical performance evaluation based on haptic feedback.

In order to develop effective virtual reality training systems for surgery there is a need to provide appropriate sensory and performance feedback to the user. This paper aims to demonstrate a method by which performance data can be collected. This is used to investigate the effect of haptic feedback on performance. A PHANTOM desktop device was used in conjunction with a suturing simulation A pair of needle-holders was instrumented with strain gauges and attached to the stylus of the PHANTOM allowing the measurement of force application and time. Suturing performance was evaluated in terms of stitch completion time, peak force application, and the length and straightness of the stitch. The effect of the level of force feedback provided by the simulation and performance over time was considered. The results indicate that the presence of force feedback affected task completion time, peak force application and the straightness of the stitch. Task completion time was shown to increase with the level of force feedback provided. Performance was seen to improve over time in terms of task completion time and the accuracy ofthe stitch. The work has examined how the presence and level of force feedback affects performance of a simple task. The accuracy of haptic feedback is important in the design of surgical simulation systems to ensure effective training transfer. A data collection method by which objective performance evaluation can be made is demonstrated. The method can be applied to training using bench models, simulations and potentially in the operating theatre.

The feasibility of a mixed reality surgical training environment

The Sheffield knee arthroscopy training system (SKATS) was originally a visual-based virtual environment without haptic feedback, but has been further developed as a mixed reality-training environment through the use of tactile augmentation (or passive haptics). The design of the new system is outlined and then tested. In the first experiment described, the effect of tactile augmentation on performance is considered by comparing novice performance using the original and mixed reality system. In the second experiment the mixed reality system is assessed in terms of construct validity by comparing the performance of users with differing levels of surgical expertise. The results are discussed in terms of the validity of a mixed reality environment for training knee arthroscopy.

Parental views on informed consent for expanded newborn screening

Background  An increasing array of rare inherited conditions can be detected as part of the universal newborn screening programme. The introduction and evaluation of these service developments require consideration of the ethical issues involved and appropriate mechanisms for informing parents and gaining consent if required. Exploration of parental views is needed to inform the debate and specifically consider whether more flexible protocols are needed to fit with the public perception of new developments in this context.

Beyond the visuals: tactile augmentation and sensory enhancement in an arthroscopy simulator

This paper considers tactile augmentation, the addition of a physical object within a virtual environment (VE) to provide haptic feedback. The resulting mixed reality environment is limited in terms of the ease with which changes can be made to the haptic properties of objects within it. Therefore sensory enhancements or illusions that make use of visual cues to alter the perceived hardness of a physical object allowing variation in haptic properties are considered. Experimental work demonstrates that a single physical surface can be made to ‘feel’ both softer and harder than it is in reality by the accompanying visual information presented. The strong impact visual cues have on the overall perception of object hardness, indicates haptic accuracy may not be essential for a realistic virtual experience. The experimental results are related specifically to the development of a VE for surgical training; however, the conclusions drawn are broadly applicable to the simulation of touch and the understanding of haptic perception within VEs.

Objective metrics for the evaluation of simple surgical skills in real and virtual domains

Surgical skills are traditionally assessed through subjective evaluation with experienced surgeons observing and rating trainee activity. However, this process can be expensive, particularly in terms of the time required of expert surgeons. Subjective assessment may also suffer from problems of intersubject variation in the application of evaluation criteria. Computer-based training, in particular systems combining virtual reality interfaces with haptic displays, offers a means of providing both automated and objective assessment of performance. In this paper we propose that, prior to the development of such systems, there is a need to determine measures that can adequately differentiate levels of performance. The paper therefore discusses the evaluation of surgical technique using objective metrics. Two main questions are addressed. How can surgical technique be assessed? What metrics prove useful in defining and modifying surgical skills and techniques?

Engineering requirements for a haptic simulator for knee arthroscopy training.

This paper describes the initial development of an innovative haptic device that will be integrated into an existing virtual reality training system for knee arthroscopy. The resulting system will be called WISHKATS (Warwick, Imperial, Sheffield Knee Arthroscopy Training System). This haptic device will enable the trainee to feel realistic forces on the probing tool and will work together with software, which will simulate tissue deformation. The proposed haptic system is a compact, multi-degree of freedom, motorised mechanism with force sensors, and will be used to simulate the diagnostic aspects of knee arthroscopy. There are a number of problems associated with the development of a suitable haptic system and this paper explores the engineering requirements of such a device.

A flexible virtual reality tutorial for the training and assessment of arthroscopic skills.

Through definition of a comprehensive tutorial model, the Warwick, Imperial and Sheffield Haptic Knee Arthroscopy Training System (WISHKATS) aims to provide independent, flexible and consistent training and assessment. The intention is to satisfy user acceptance by limiting the constraints by which the system can be utilised, as well as demonstrating validity and reliability. System use can either be under the guidance and feedback offered by the system or of a senior surgeon. Objective metrics are defined for performance feedback and formal assessment.

Improving wheelchair prescription: an analysis of user needs and existing tools

Wheelchair users experience many situations that affect the stability and associated performance of their wheelchair. Stability is affected by user characteristics and abilities, environmental features and conditions, and wheelchair modification and accessories. Wheelchair prescribers need effective tools and methods to provide quantitative evaluation and prediction of the behavior of the user-wheelchair system in a variety of static and dynamic situations. Such information is very important to guide efficient management of associated risks and adjust chairs accordingly. This project involves a user-centered approach for design and evaluation of a load cell based wheelchair stability assessment system (Wheel-SAS). Here, the current methods for assessing stability are described, and their shortcomings explained. The user-centered design approach being applied to the development of the associated Wheel-SAS hardware and software is described. Future work including semi-structured interviews and an online survey with wheelchair prescribers and associated healthcare professionals for deriving user requirements and a design specification for a load cell system for measuring dynamic wheelchair stability are detailed.

A part-task approach to haptic knee arthroscopy training.

This paper describes the research behind a part-task approach to both the development of, and the training offered, by a virtual reality simulator for knee arthroscopy. An ethnographic approach has been taken to examine the nature of task performance and the current training of the arthroscopic diagnosis of the knee. This Human Factors research is used to support the development of WISHKATS. The design addresses the challenge of technically producing haptic feedback for a knee surgery simulator whilst offering sufficient fidelity to train the necessary skills and conform to traditional surgical training.