Risk of rupture of small anterior communicating artery aneurysms is similar to posterior circulation aneurysms.

BACKGROUND AND PURPOSE: According to the International Study of Unruptured Intracranial Aneurysms (ISUIA), anterior circulation (AC) aneurysms of <7 mm in diameter have a minimal risk of rupture. It is general experience, however, that anterior communicating artery (AcoA) aneurysms are frequent and mostly rupture at <7 mm. The aim of the study was to assess whether AcoA aneurysms behave differently from other AC aneurysms. METHODS: Information about 932 patients newly diagnosed with intracranial aneurysms between November 1, 2006, and March 31, 2012, including aneurysm status at diagnosis, its location, size, and risk factors, was collected during the multicenter @neurIST project. For each location or location and size subgroup, the odds ratio (OR) of aneurysms being ruptured at diagnosis was calculated. RESULTS: The OR for aneurysms to be discovered ruptured was significantly higher for AcoA (OR, 3.5 [95% confidence interval, 2.6-4.5]) and posterior circulation (OR, 2.6 [95% confidence interval, 2.1-3.3]) than for AC excluding AcoA (OR, 0.5 [95% confidence interval, 0.4-0.6]). Although a threshold of 7 mm has been suggested by ISUIA as a threshold for aggressive treatment, AcoA aneurysms <7 mm were more frequently found ruptured (OR, 2.0 [95% confidence interval, 1.3-3.0]) than AC aneurysms of 7 to 12 mm diameter as defined in ISUIA. CONCLUSIONS: We found that AC aneurysms are not a homogenous group. Aneurysms between 4 and 7 mm located in AcoA or distal anterior cerebral artery present similar rupture odds to posterior circulation aneurysms. Intervention should be recommended for this high-risk lesion group.

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.

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.

Ensuring the usability of a knee arthroscopy simulator.

There is limited research considering the usability of medical virtual environments. Usability evaluation is an essential validation phase that considers the extent to which a product achieves its specific goals, with effectiveness, efficiency and satisfaction. A four-stage iterative approach is adopted to enhance usability in the development of a knee arthroscopy training system. This process has drawn attention to issues that may impede system usability for example non-conformity to platform conventions, and visibility of the system status. The process highlights features that computer scientists can overlook when working closely with a system but that are essential to user acceptance and effective application.

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.

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 confirmed 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 validity 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.