Sofia Bayona

Assessing Performance in Shoulder Arthroscopy: The Imperial Global Arthroscopy Rating Scale (IGARS)

BACKGROUND Surgical training is undergoing major changes with reduced resident work hours and an increasing focus on patient safety and surgical aptitude. The aim of this study was to create a valid, reliable method for an assessment of arthroscopic skills that is independent of time and place and is designed for both real and simulated settings. The validity of the scale was tested using a virtual reality shoulder arthroscopy simulator. METHODS The study consisted of two parts. In the first part, an Imperial Global Arthroscopy Rating Scale for assessing technical performance was developed using a Delphi method. Application of this scale required installing a dual-camera system to synchronously record the simulator screen and body movements of trainees to allow an assessment that is independent of time and place. The scale includes aspects such as efficient portal positioning, angles of instrument insertion, proficiency in handling the arthroscope and adequately manipulating the camera, and triangulation skills. In the second part of the study, a validation study was conducted. Two experienced arthroscopic surgeons, blinded to the identities and experience of the participants, each assessed forty-nine subjects performing three different tests using the Imperial Global Arthroscopy Rating Scale. Results were analyzed using two-way analysis of variance with measures of absolute agreement. The intraclass correlation coefficient was calculated for each test to assess inter-rater reliability. RESULTS The scale demonstrated high internal consistency (Cronbach alpha, 0.918). The intraclass correlation coefficient demonstrated high agreement between the assessors: 0.91 (p < 0.001). Construct validity was evaluated using Kruskal-Wallis one-way analysis of variance (chi-square test, 29.826; p < 0.001), demonstrating that the Imperial Global Arthroscopy Rating Scale distinguishes significantly between subjects with different levels of experience utilizing a virtual reality simulator. CONCLUSIONS The Imperial Global Arthroscopy Rating Scale has a high internal consistency and excellent inter-rater reliability and offers an approach for assessing technical performance in basic arthroscopy on a virtual reality simulator. CLINICAL RELEVANCE The Imperial Global Arthroscopy Rating Scale provides detailed information on surgical skills. Although it requires further validation in the operating room, this scale, which is independent of time and place, offers a robust and reliable method for assessing arthroscopic technical skills.

Neuronize: a tool for building realistic neuronal cell morphologies

This study presents a tool, Neuronize, for building realistic three-dimensional models of neuronal cells from the morphological information extracted through computer-aided tracing applications. Neuronize consists of a set of methods designed to build 3D neural meshes that approximate the cell membrane at different resolution levels, allowing a balance to be reached between the complexity and the quality of the final model. The main contribution of the present study is the proposal of a novel approach to build a realistic and accurate 3D shape of the soma from the incomplete information stored in the digitally traced neuron, which usually consists of a 2D cell body contour. This technique is based on the deformation of an initial shape driven by the position and thickness of the first order dendrites. The addition of a set of spines along the dendrites completes the model, building a final 3D neuronal cell suitable for its visualization in a wide range of 3D environments.

Comparing sphere-tree generators and hierarchy updates for deformable objects collision detection

This paper presents a quantitative evaluation of the accuracy of different sphere-tree construction methods when they are used in deformable bodies. The methods evaluated are Grid (an extension of octrees), Hubbard, Adaptive Medial Axis and Spawn. We also present a new approach to update the sphere-tree hierarchy that ensures lower loss of accuracy than in traditional update techniques.

Mechanical Design of a Minimally Invasive Surgery Trainer Using the Manipulability as Measure of Optimization

The trainers based in virtual reality have come up with an enormous interest in the field of Minimally Invasive Surgery. They provide a non degradable realistic training environment where apprentices are able to gain skills without limitations or risks. They may learn and try as much as desired, with no additional cost after the installation of the system. In this paper, we describe our contribution to a multidisciplinary project for the development of a Minimally Invasive Surgery Trainer. The aim of our work has been to optimize the mechanical relative positioning of haptic devices into the system platform. With this purpose we have defined a measure of how the operation workspace fits within the volume where haptic device provides its best manipulability. Then we have defined another measure that takes into account the frequency with which each zone of the operation workspace is visited during the simulation session. Using these tools, a prototype of mechanical platform involving two haptic devices has been designed and built. The placement of each device has been optimized for each zone of the operation workspace in function of its role, manipulability and frequency of use.

A New User-Adapted Search Haptic Algorithm to Navigate along Filiform Structures

One of the mayor research challenges of this century is the understanding of the human brain. Regarding this field line, simulation based research is gaining importance. A large amount of money is being spent in huge international projects such as The Human Brain Project [1] and The Blue Brain [2]. The behavior of the brain and, therefore, the behavior of brain simulations depend to a large extend on the neural topology. Neural elements are organized in a connected, dense, complex network of thread-like (i.e, filiform) structures. The analysis of a computer-based simulation using just the visual modality is a highly complex task due to the complexity of the neural topology and the large amounts of multi-variable and multi-modal data generated by computer simulations. In this paper, we propose the use of haptic devices to aid in the navigation along these neural structures, helping neurobiologists in the analysis of neural network topologies. However, haptic navigation constrained to complex filiform networks entails problems when these structures have high frequency features, noise and/or complex branching nodes. We address these issues by presenting a new user-adapted search haptic method that uses the forces exerted by the users to infer their intentions. In addition, we propose a specific calibration technique to adapt the haptic navigation to the users skills and to the data. We validate this approach through a perceptual study. Finally, we show in this paper the application of our method to the analysis of dense and complex filiform structures in the neurobiology context. Additionally, our technique could be applied to other problems such as electronic circuits and graph exploration.

Haptically Assisted Connection Procedure for the Reconstruction of Dendritic Spines

Dendritic spines are thin protrusions that cover the dendritic surface of numerous neurons in the brain and whose function seems to play a key role in neural circuits. The correct segmentation of those structures is difficult due to their small size and the resulting spines can appear incomplete. This paper presents a four-step procedure for the complete reconstruction of dendritic spines. The haptically driven procedure is intended to work as an image processing stage before the automatic segmentation step giving the final representation of the dendritic spines. The procedure is designed to allow both the navigation and the volume image editing to be carried out using a haptic device. A use case employing our procedure together with a commercial software package for the segmentation stage is illustrated. Finally, the haptic editing is evaluated in two experiments; the first experiment concerns the benefits of the force feedback and the second checks the suitability of the use of a haptic device as input. In both cases, the results shows that the procedure improves the editing accuracy.

A GLOBAL APPROACH TO THE DESIGN AND EVALUATION OF VIRTUAL REALITY MEDICAL SIMULATORS

VR Simulators are a powerful alternative to traditional educational techniques in many domains; and in particular, in surgery. Although they offer new possibilities for learning, training and assessment, they still found difficult to be accepted and integrated into hospitals. In this paper, we explain what we consider the key issues to create successful VR simulators, and we present two methodologies: the guidelines for the simulator design and the evaluation of their validity. Research on VR surgical simulators should be interdisciplinary. It involves medicine, educational psychology, computer science, and engineering. Optimal interdisciplinary communication is difficult, and most projects in surgical simulation are strongly influenced by the engineering perspective, with little or no contributions from the others. This unbalance often leads to a premature end of the project or to simulators which are less practical for surgeons. A design methodology should be used as a guide in the process of creating VR simulators. A thorough description of the problem, the simulator’s role, and an exhaustive task analysis will lead to the identification of the requirements. For the technical implementation, decisions will be taken related to the hardware interface and the interaction that users will have with the virtual world; which will determine collision detection and response algorithms, and the behaviour of the 3D models. In addition to the technical testing, it is necessary to prove the validity of the simulator and design procedures to measure the user performance. We explain a methodology to evaluate the validity (face, content, and criterion-related validity), reliability and transfer of skills from a VR simulator to the real environment in a structured and rigorous way. Following this methodology, an evaluation experiment involving 19 orthopaedic doctors using a VR arthroscopy simulator was carried out. Results prove face and content validities, and inform about the factors and measures that are considered important for arthroscopic surgery. In order to consolidate the research results, we encourage the establishment of an intersectorial consortium with agents from the academic, healthcare and industrial sectors to ensure the long-term sustainability of research lines, additional funding, and to guarantee that simulators, once validated, can be widely available in hospitals. This paper presents a global approach including relevant guidelines and methodologies for designing and evaluating VR simulators. It can provide a solid structure for other researchers when facing those processes and contribute to the successful integration of VR simulators within the educational curriculum.Copyright