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At least 91 records · Page 5Linked to original sources
PubMed2001

Force-feedback in Web-based surgical simulators.

There is a growing requirement in the field of surgical training to allow trainees to practice procedures in a way that does not place patients in any risk. Computer based simulators allow students to gain experience and develop three-dimensional awareness in a safe and controlled environment. Typically systems that have been developed to perform this task are, due to their specialist nature, expensive to buy. With the increasing availability of Force-Feedback devices for the gaming market, is there now a cost-effective alternative for surgical simulations? In this paper we investigate the possibility of using such a device as a haptic input tool for surgical simulations.

Computer Simulation↗
PubMed2005

A surgical simulator for planning and performing repair of cleft lips.

UNLABELLED: The objective of this project was to develop a computer-based surgical simulation system for planning and performing cleft lip repair. This system allows the user to interact with a virtual patient to perform the traditional steps of cleft-lip repair (rotation-advancement technique). MATERIALS AND METHODS: The system interfaces to force-feedback (haptic) devices to track the user's motion and provide feedback during the procedure, while performing real-time soft-tissue simulation. An 11-day-old unilateral cleft lip, alveolus and palate patient was previously CT scanned for ancillary diagnostic purposes using standard imaging protocols and 1mm slices. High-resolution 3D meshes were automatically generated from this data using the ROVE software developed in-house. The resulting 3D meshes of bone and soft tissue were instilled with physical properties of soft tissues for purposes of simulation. Once these preprocessing steps were completed, the patient's bone and soft tissue data are presented on the computer screen in stereo and the user can freely view, rotate, and otherwise interact with the patient's data in real time. The user is prompted to select anatomical landmarks on the patient's data for preoperative planning purposes, then their locations are compared against that of a 'gold standard' and a score, derived from their deviation from that standard and time required, is generated. The user can then move a haptic stylus and guide the motion of the virtual cutting tool. The soft tissues can thus be incised using this virtual cutting tool, moved using virtual forceps, and fused in order to perform any of the major procedures for cleft lip repair. Real-time soft tissue deformation of the mesh realistically simulates normal tissues and haptic-rate (>1 kHz) force-feedback is provided. The surgical result of the procedure can then be immediately visualized and the entire training process can be repeated at will. A short evaluation study was also performed. Two groups (non-medical and plastic surgery residents) of six persons each performed the anatomical marking task of the simulator four times. RESULTS: Results showed that the plastic surgery residents scored consistently better than the persons without medical background. Every person's score increased with practice, and the length of time needed to complete the 11 markings decreased. The data was compiled and showed which specific markers consistently took users the longest to identify as well as which locations were hardest to accurately mark. CONCLUSION: These findings suggest that the simulator is a valuable training tool, giving residents a way to practice anatomical identification for cleft lip surgery without the risks associated with training on a live patient. Educators can also use the simulator to examine which markers are consistently problematic, and modify their training to address these needs.

Cleft Lip↗
PubMed2002

Validation and learning in the Procedicus KSA virtual reality surgical simulator.

BACKGROUND: Advanced simulator training within medicine is a rapidly growing field. Virtual reality simulators are being introduced as cost-saving educational tools, which also lead to increased patient safety. METHODS: Fifteen medical students were included in the study. For 10 medical students performance was monitored, before and after 1 h of training, in two endoscopic simulators (the Procedicus KSA with haptic feedback and anatomical graphics and the established MIST simulator without this haptic feedback and graphics). Five medical students performed 50 tests in the Procedicus KSA in order to analyze learning curves. One of these five medical students performed multiple training sessions during 2 weeks and performed more than 300 tests. RESULTS: There was a significant improvement after 1 h of training regarding time, movement economy, and total score. The results in the two simulators were highly correlated. CONCLUSION: Our results show that the use of surgical simulators as a pedagogical tool in medical student training is encouraging. It shows rapid learning curves and our suggestion is to introduce endoscopic simulator training in undergraduate medical education during the course in surgery when motivation is high and before the development of "negative stereotypes" and incorrect practices.

Computer Simulation↗
PubMed2006

GiPSi:a framework for open source/open architecture software development for organ-level surgical simulation.

This paper presents the architectural details of an evolving open source/open architecture software framework for developing organ-level surgical simulations. Our goal is to facilitate shared development of reusable models, to accommodate heterogeneous models of computation, and to provide a framework for interfacing multiple heterogeneous models. The framework provides an application programming interface for interfacing dynamic models defined over spatial domains. It is specifically designed to be independent of the specifics of the modeling methods used, and therefore facilitates seamless integration of heterogeneous models and processes. Furthermore, each model has separate geometries for visualization, simulation, and interfacing, allowing the model developer to choose the most natural geometric representation for each case. Input/output interfaces for visualization and haptics for real-time interactive applications have also been provided.

Computer Simulation↗
PubMed2000

An initial evaluation of the Iowa Dental Surgical Simulator.

The University of Iowa colleges of dentistry and engineering are collaborating to build an effective but low-cost surgical simulator that uses force feedback to teach and assess the tactile skills of dentistry. A prototype simulator was built, and a formative evaluation examined the realism of the haptics and identified directions for future work. Using a cross-over design, twelve experienced practitioners probed two virtual teeth using two instruments attached to the force feedback device. The session was videotaped, the forces recorded, and a standardized questionnaire completed. Two analyses were conducted: an ANOVA examined practitioners' questionnaire responses, and a t-test analyzed the probing forces. Significant tooth order by instrument order interaction and instrument effects were found. Practitioners were generally satisfied. They preferred a standard joystick to an explorer, felt that two-dimensional graphics were sufficient, and emphasized that the existing vibration be eliminated. Random placement of caries should help teach generalized skills.

Analysis of Variance↗
PubMed1999

Fast finite element modeling for surgical simulation.

Given the geometric complexity of anatomical structures, realistic real-time deformation of graphical reconstructions is prohibitively computationally intensive. Instead, real-time deformation of virtual anatomy is roughly approximated through simpler methodologies. Since the graphical interpolations and simple spring models commonly used in these simulations are not based on the biomechanical properties of tissue structures, these "quick and dirty" methods typically do not accurately represent the complex deformations and force-feedback interactions that can take place during surgery. Finite element (FE) analysis is widely regarded as the most appropriate alternative to these methods. Extensive research has been directed toward applying the method to modeling a wide range of biological structures, and a few simple FE models have been incorporated into surgical simulations. However, because of the highly computational nature of the FE method, its direct application to real-time force-feedback and visualization of tissue deformation has not been practical for most simulations. This limitation is primarily due to the overabundance of information provided by the standard FE approaches. If the mathematics is optimized to yield only the information essential for the surgical task, computation time can be drastically reduced. Parallel computation and preprocessing of the model before the simulation begins can also reduce the size of the problem and greatly increase computation speed. Such methodologies are being developed in a combined effort between the Human Interface Technology Laboratory (HIT Lab) and the Mechanical Engineering Department of the University of Washington. We have created computer demonstrations which support real-time interaction with simple finite element soft tissue models. In collaboration with the Division of Dermatology, a real-time skin surgery simulator is being developed using these fast FE methods.

Computer Simulation↗
PubMed2002

Measurement of in-vivo force response of intra-abdominal soft tissues for surgical simulation.

The lack of data on in-vivo material properties of soft tissues has been a significant impediment in the development of virtual reality based surgical simulators that can provide the user with realistic visual and haptic feedback. As a first step towards characterizing the mechanical behavior of organs, this work presents in-vivo force response of the liver and lower esophagus of pigs when subjected to ramp and hold, and sinusoidal indentations delivered using a haptic feedback device, Phantom, employed as a mechanical stimulator. The results show that pulse significantly affects the reaction forces and that the lower esophagus is 2 to 2.5 times stiffer than the liver.

Abdomen↗
PubMed2005

Heterogeneous displays for surgery and surgical simulation.

Instruments and procedures continue to become more complex and challenging, but the display environments to which these technologies are connected have not kept pace. Display real-estate (the size and resolution of the display), the configurability of the display, and the ability for display systems to incorporate, fuse and present diverse informational sources are limiting factors. The capabilities of display technologies are far exceeded by the procedures and instruments that rely on them. In this paper we show how to break free from display constraints by moving forward with a hybrid, heterogeneous display framework that preserves key characteristics of current systems (low latency, specialized devices). We have engineered a hybrid display and are currently using it to build a surgical simulation and training environment within which we can evaluate both the technology and the performance of subjects using the technology.

Computer Simulation↗
PubMed2006

Surgical simulation of instrumented posterior occipitocervical fusion in a child with congenital skeletal anomaly: case report.

STUDY DESIGN: Case report of a child with a congenital skeletal anomaly who underwent instrumented surgery at the craniovertebral junction (CVJ). OBJECTIVES: To describe the utility of surgical simulation using three-dimensional full-scale models for preoperative planning. SUMMARY OF BACKGROUND DATA: Instrumented fusion of cervical spine with pedicle screws has several advantages compared with conventional sublaminar wiring, such as stronger fixation and reduction of malalignment. However, studies have reported a risk of injury to the vertebral artery (VA) from the insertion of screws. Especially in pediatric patients, the safety of pedicle screw insertion has not been fully established. METHODS: A 7-year-old girl with a congenital skeletal anomaly presented with gait disturbance and clumsiness of her right hand. Radiographs showed dysplasia of the C1 posterior arch, leading to compression of the spinal cord posteriorly. Data from three-dimensional computed tomography (CT) angiography showed that the right VA was dominant and was shifted medially at the C2 pedicle. A surgical procedure was scheduled to resect the C1 posterior arch and perform an instrumented occiput-C2 fusion with a system of rod and screws. To evaluate the adaptation of the system to the small and deformed anatomic structure of her CVJ, we produced a three-dimensional full-scale model from CT data and performed a simulation of the scheduled surgery. RESULTS: Simulation of the surgery on the model showed acceptable adaptation of the system. However, the right C2 pedicle screw penetrated the medial wall of the VA foramen. In response to these results, we altered the surgical procedure and performed occiput-C3 fixation with a system of contoured loop and wiring. Although the patient had to use a halo-vest for 2 months, no complication occurred during surgery, and she experienced relief of her myelopathy after surgery. CONCLUSIONS: The three-dimensional full-scale model was useful for determining the safety of instrumented posterior occipitocervical fusion for a pediatric patient with a skeletal anomaly.

Atlanto-Occipital Joint↗
PubMed1989

Protective effects of recombinant human tumour necrosis factor alpha and interferon gamma against surgically simulated wound infection in mice.

Tumour necrosis factor alpha and interferon gamma have both been shown to have immunoregulatory properties, and to be able to influence, several microbial infections. This study showed that tumour necrosis factor was effective in modifying surgically simulated wound infections when administered both as prophylaxis and as therapy. Two models were used; one was an intramuscular bacterial challenge, and the other involved the use of a bacteria-laden thigh suture. The test bacterium for both models was Klebsiella pneumoniae, a common surgical pathogen in our surgical service. Interferon gamma was an effective biological response modifier in these models. Tumour necrosis factor was more potent than interferon gamma and there was no additive or synergistic effect with interferon gamma. This indicates potentially different mechanisms of action for these two cytokines.

Animals↗
PubMed2004

Identifying and reducing errors with surgical simulation.

The major determinant of a patient's safety and outcome is the skill and judgment of the surgeon. While knowledge base and decision processing are evaluated during residency, technical skills-which are at the core of the profession-are not evaluated. Innovative state of the art simulation devices that train both surgical tasks and skills, without risk to patients, should allow for the detection and analysis of errors and "near misses". Studies have validated the use of a sophisticated endoscopic sinus surgery simulator (ES3) for training residents on a procedural basis. Assessments are proceeding as to whether the integration of a comprehensive ES3 training programme into the residency curriculum will have long term effects on surgical performance and patient outcomes. Using various otolaryngology residencies, subjects are exposed to mentored training on the ES3 as well as to minimally invasive trainers such as the MIST-VR. Technical errors are identified and quantified on the simulator and intraoperatively. Through a web based database, individual performance can be compared against a national standard. An upgraded version of the ES3 will be developed which will support patient specific anatomical models. This advance will allow study of the effects of simulated rehearsal of patient specific procedures (mission rehearsal) on patient outcomes and surgical errors during the actual procedure. The information gained from these studies will help usher in the next generation of surgical simulators that are anticipated to have significant impact on patient safety.

Computer-Assisted Instruction↗
PubMed2006

Working memory and image guided surgical simulation.

We report on a study that investigates the relationship between visual working memory and verbal working memory and a performance measure in endoscopic instrument navigation in MIST and GI Mentor II (a simulator for gastroendoscopy). Integrated cognitive neuroscience in state-of-the-art simulator training curriculum will take safety science in health care one step ahead. Current simulator validation focuses on how to train. In the light of recent research it is now prime time to ask why in search of mechanisms rather than to repeatedly show that training has effect. This will help tailor training to maximize individual output in procedures that require a high level of dexterity. WM training is a unique learning aid in simulator training and should be used alongside clinical practice in order to improve the quality of complex clinical intervention in the field of image guided surgical simulation.

Computer Simulation↗
PubMed2005

Consensus guidelines for validation of virtual reality surgical simulators.

The Work Group for Evaluation and Implementation of Simulators and Skills Training Programmes is a newly formed sub-group of the European Association of Endoscopic Surgeons (EAES). This work group undertook a review of validation evidence for surgical simulators and the resulting consensus is presented in this article. Using clinical guidelines criteria, the evidence for validation for six different simulators was rated and subsequently translated to a level of recommendation for each system. The simulators could be divided into two basic types; systems for laparoscopic general surgery and flexible gastrointestinal endoscopy. Selection of simulators for inclusion in this consensus was based on their availability and relatively widespread usage as of July 2004. Whilst level 2 recommendations were achieved for a few systems, it was clear that there was an overall lack of published validation studies with rigorous experimental methodology. Since the consensus meeting, there have been a number of new articles, system upgrades and new devices available. The work group intends to update these consensus guidelines on a regular basis, with the resulting article available on the EAES website (http://www.eaes-eur.org ).

Computer Simulation↗
PubMed1984

Staphylococcal lysate fails to elicit nonspecific immune enhancement in a simulated surgical infection.

Staphylococcus aureus produces a delayed-type hypersensitivity reaction, which results in some degree of nonspecific immune enhancement. The authors chose to observe the effects of staphylococcal vaccine (staphage lysate) as a possible potentiator of nonspecific immunity. The experiments were performed in a well-known model simulating surgical infection. The experimental results do not support the previously proposed hypothesis that staphylococcal vaccine improves the immune response to a bacterial challenge.

Animals↗
PubMed1998

[Accuracy of computerized aid diagnosis, surgical simulation and facial appearance prediction in orthognathic surgery].

OBJECTIVE: The purpose of this report is to evaluated the accuracy and potential advantages of the computer system in orthognathic surgery. METHODS: The accuracy of computer prediction was evaluated in 31 patients by using the orthognathic surgery prediction expert system (OSPES) in the preoperative analysis, diagnosis, surgical simulation and preoperative facial appearance predication. RESULTS: This system could accurately predict the postoperative changing. The prediction accuracy for single-jaw surgery was over 95%; double-jaw 85%. The prediction for hard tissue was more accurate than that for soft tissue. CONCLUSION: The results of this study suggest that computer system is an acceptable tool for facial appearance prediction.

Computer Simulation↗
PubMed2004

Combined compression and elongation experiments and non-linear modelling of liver tissue for surgical simulation.

Uniaxial stress-strain data were obtained from in vitro experiments on 20 porcine livers for compressions, elongations and cycles of compression and then elongation. There were about 70 cylindrical samples, with diameter 7mm and varying height (4-11 mm). The combined compression and elongation test provide a unified framework for both compression and elongation for applications such as computer-aided surgical simulation. It enable the zero stress state of the experimental liver sample to be precisely determined. A new equation that combined both logarithmic and polynomial strain energy forms was proposed in modelling these experimental data. The assumption of incompressibility was justified from a preliminary Poisson's ratio for elongation and compression at 0.43+/-0.16 and 0.47+/-0.15, respectively. This equation provided a good fit for the observed mechanical properties of liver during compression-elongation cycles and for separate compressions or elongations. The root mean square errors were 91.92+/-17.43 Pa, 57.55+/-13.23 Pa and 29.78+/-17.67 Pa, respectively. In comparison with existing strain energy functions, this combined model was the better constitutive equation. Application of this theoretical model to small liver samples and other tissues demonstrated its suitability as the material model of choice for soft tissue.

Animals↗
PubMed2000

Surgical simulation of Class III edentulous patient using a 3D craniofacial model: report of a case.

A case of edentulous prognathism in a 46-year-old Japanese male is presented. We described the outcome of the patient who underwent simultaneous sagittal splitting ramus osteotomy of the edentulous mandible, interpositional bone graft of severely atrophic edentulous jaws, and delayed placement of titanium implants for reconstruction. We highly recommend performing a surgical simulation using a craniofacial model of the patient's anatomy created using CT image data. The procedure provides almost ideal maxillary and mandibular contours.

Alveolar Ridge Augmentation↗