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PubMed2003

Training in tasks with different visual-spatial components does not improve virtual arthroscopy performance.

BACKGROUND: We earlier showed that training in the Procedicus KSA Simulator improves the performance of tasks done later in the same simulator. However, it is still unclear how performance in a specific visual-spatial simulator context may change after training in other simulators with different visual-spatial components. In particular, the aim of this study was to test whether performance in the Procedicus Virtual Arthroscopy (VA) Knee Simulator would remain unchanged after a training session in three other simulators with different visual-spatial components. METHODS: Twenty-eight medical students participated in a quasi-transfer study. They were randomly allocated to an experimental group ( n = 14) and a control group ( n = 14). RESULTS: Performance in the Procedicus VA Knee Simulator did not improve after training in other simulators with different visual-spatial components ( t-test p = NS). No significant correlation was found between the Procedicus VA Knee and the Minimally Invasive Surgical Trainer (MIST) simulators. CONCLUSION: One hour of training in different visual-spatial contexts was not enough to improve the performance in virtual arthroscopy tasks. It cannot be excluded, however, that experienced trainees could improve their performance, because perceived similarity between different situations is influenced by many psychological factors, such as the knowledge or expertise of the person performing the transfer task.

Adult↗
PubMed2005

The effect of valgus/varus malalignment on load distribution in total knee replacements.

Valgus or varus malpositioning of the tibial component of a total knee implant may cause increased propensity for loosening or implant wear and eventually may lead to revision surgery. The aim of this study was to determine the effect of valgus/varus malalignment on tibio-femoral mechanics during surgical trial reduction and simulated gait loading. In seven cadaver legs, posterior cruciate sparing total knee replacements were implanted and tibial inserts representing a neutral alignment and 3 degrees and 5 degrees varus and valgus alignments were sequentially inserted. Each knee with each insert was loaded in a manner representative of a trial reduction performed during knee surgery and loaded in a physiological knee simulator. Simulated gait performed on the simulator demonstrated that internal/external and adduction/abduction rotations showed statistical changes with some of the angled inserts at different points in the walking cycle. Neither medial/lateral nor anterior/posterior translations changed statistically during simulated walking. The pressure distribution and total load in the medial and lateral compartments of the tibial component changed significantly with as little as a 3 degrees variation in angulation when loaded in a manner representative of a trial reduction or with a knee simulator. These results support the need for precise surgical reconstruction of the mechanical axis of the knee and proper alignment of the tibial component. These results further demonstrate that tibial contact pressures measured during a trial reduction method may be predictive of contact mechanics at the higher loading seen in the knee simulator.

Arthroplasty, Replacement, Knee↗
PubMed1995

Computer-simulated eye surgery. A novel teaching method for residents and practitioners.

PURPOSE: To describe an eye surgery simulator that uses a computerized graphic display to allow ophthalmic surgeons of all experience levels to enhance their surgical skills. METHODS: The eye surgery simulation environment consists of a high-speed computer graphics workstation, a stereo operating system, a wrist rest, and a position tracking stylus connected to force feedback motors. The surgeon views computer-generated images of the eye and surgical instruments through the stereo operating system and controls the position and orientation of the chosen surgical instrument by moving the stylus. During the simulated instrument-tissue interactions, three feedback motors generate component force feedback along three orthogonal axes connected by thin rigid bars to the tip of the stylus. RESULTS: The current proof-of-concept system provides a method for rapid learning experiences in a living eye simulation. Procedures can be recorded for playback and analysis, as well as for examination of techniques from different viewpoints (e.g., from inside the eye). Four simulated surgical instruments are available for use (scalpel, forceps, scissors, and phacoemulsifier). CONCLUSION: Eye surgery simulation offers both beginning and experienced ophthalmic surgeons an opportunity to learn new techniques and skills and achieve a satisfactory level of proficiency before use of that procedure in the operating room. When fully developed, this system should shorten the learning curve for new surgeons (i.e., residents) and offer an opportunity for practice before doing a difficult case or development of new techniques by experienced surgeons. The goal of replacement of current standard training methods for surgeons awaits further refinement and adjustment of the model.

Computer Simulation↗
PubMed2006

A competency-based virtual reality training curriculum for the acquisition of laparoscopic psychomotor skill.

BACKGROUND: Studies have demonstrated the beneficial effect of training novice laparoscopic surgeons using virtual reality (VR) simulators, although there is still no consensus regarding an optimal VR training curriculum. This study aims to establish and validate a structured VR curriculum to provide an evidence-based approach for laparoscopic training programmes. METHODS: The minimally invasive VR simulator (MIST-VR) has 12 abstract laparoscopic tasks, each at 3 graduated levels of difficulty (easy, medium, and hard). Twenty medical students completed 2 sessions of all tasks at the easy level, 10 sessions at the medium level, and finally 5 sessions of the 2 most complex tasks at the hard level. At the medium level, subjects were randomized into 2 equal groups performing either all 12 tasks (group A) or the 2 most complex tasks (group B). Performance was measured by time taken, path length, and errors for each hand. The results were compared between groups, and to those of 10 experienced laparoscopic surgeons. RESULTS: Baseline performance of both groups was similar at the easy level. At the medium level, learning curves for all 3 parameters reached plateau at the second (group A, P < .05) and sixth (group B, P < .05) repetitions. Performance at the hard level was similar between the 2 groups, and all achieved the pre-set expert criteria. CONCLUSION: A graduated laparoscopic training curriculum enables trainees to familiarise, train and be assessed on laparoscopic VR simulators. This study can aid the incorporation of VR simulation into established surgical training programmes.

Adolescent↗
PubMed1989

Presurgical finite element simulation of scoliosis correction.

For surgical correction of scoliotic spinal deformity, internal fixation systems apply lateral and distractive corrective forces. In order to gain maximal correction, a finite--element analysis of the spinal deformity correction technique has been carried out preoperatively, after first employing the spinal deformity correction finite--element model to determine the in vivo spinal stiffness. The presurgical analysis also gives us an appreciation of how the parameters of deformity, stiffness and corrective forces jointly contribute to the value of the correction index. The paper presents the methodology and clinical application. It also summarizes the results for ten patients, whereby the efficacy of presurgical analysis is assessed by comparing the corrective index values by presurgical simulation with the surgical results for equivalent levels of corrective forces.

Adolescent↗
PubMed1996

The expert surgical assistant. An intelligent virtual environment with multimodal input.

Virtual Reality has made computer interfaces more intuitive but not more intelligent. This paper shows how an expert system can be coupled with multimodal input in a virtual environment to provide an intelligent simulation tool or surgical assistant. This is accomplished in three steps. First, voice and gestural input is interpreted and represented in a common semantic form. Second, a rule-based expert system is used to infer context and user actions from this semantic representation. Finally, the inferred user actions are matched against steps in a surgical procedure to monitor the user's progress and provide automatic feedback. In addition, the system can respond immediately to multimodal commands for navigational assistance and/or identification of critical anatomical structures. To show how these methods are used we present a prototype sinus surgery interface. The approach described here may easily be extended to a wide variety of medical and non-medical training applications by making simple changes to the expert system database and virtual environment models. Successful implementation of an expert system in both simulated and real surgery has enormous potential for the surgeon both in training and clinical practice.

Artificial Intelligence↗
PubMed2005

3D Real-time FEM based guide wire simulator with force feedback.

Minimally invasive surgical techniques using catheter is now used in many procedures. Development of surgical training of such procedures requires real-time simulation of tool-organ interaction. In such processes, each subsequent step of interaction would be based on the current configuration of the surgical tool (guidewire in this case), leading to development of techniques to solve and visualize the configuration of tool at every time step. This paper presents a Finite Element (FEM) based approach to simulate the tool-organ interaction.

Catheterization↗
PubMed2003

Microanatomical and neuroendoscopic studies of the internal auditory meatus and its surrounding structures.

OBJECTIVE: To observe the morphology of the internal auditory meatus in relation with its surrounding structures in Chinese people, for the purpose of providing microanatomical reference for surgeries adopting retro-sigmoid approach. METHODS: The retro-sigmoid surgical approach was simulated on 5 fresh specimens of human head, in which the internal auditory meatus and its surrounding structures were observed through a neuroendoscope and a surgical microscope. The distances from the posterior inferior edge of the internal auditory meatus to the central point of the posterior edge of the sigmoid sinus and to the posterior edge of the posterior semicircular canal were measured. RESULTS: The internal auditory meatus was located at the center of the medial surface of the petrous bone, and the cranial nerve VII ran through its anterior-superior part while the cranial nerve VIII through its posterior-inferior part. After forming an arterial loop at the internal auditory meatus, the anterior-inferior cerebellar artery branched into 1 to 3 internal auditory arteries. The distance from the posterior-inferior edge of the internal auditory meatus to the central point of the posterior edge of the sigmoid sinus was 32.15+/-1.76 mm on the left side, and 33.34+/-1.57 mm on the right, and the distance to the posterior edge of the posterior semicircular canal was 12.51+/-2.15 mm on the left side, and 13.26+/-2.44 mm on the right. CONCLUSION: Thorough knowledge of the microanatomy of the internal auditory meatus and its surrounding structures is of crucial importance to preserve the functions of the cranial nerves VII and VIII in the surgical removal of acoustic neuroma.

Asian People↗
PubMed1989

Nonsurgical and extraperitoneal causes of abdominal pain.

Most patients presenting to the emergency department with acute abdominal pain suffer from disorders requiring other than surgical intervention. Unnecessary morbidity may be avoided through understanding the anatomic and physiologic variables involved in producing abdominal pain. Table 1 lists conditions that may simulate an acute surgical abdomen. Selected disorders were discussed.

Abdomen↗
PubMed2002

[Geometry of laparoscopy, telesurgery, training and telementoring].

Laparoscopic surgery in general is handicapped by the reduction of the range of motion from 6 to 4 degrees of freedom. This has a major impact on technically difficult procedures such as laparoscopic radical prostatectomy. Solutions for this problem include understanding the geometry of laparoscopy with sophisticated training programs, but also newly developed surgical robots, computer simulators, and telementoring. This article evaluates the value of these alternatives based on own experience and an analysis of the current literature. Our experience with robot-assisted surgery includes 244 laparoscopic radical prostatectomies using a voice-controlled camera arm (AESOP) and 6 telesurgical interventions with the da Vinci system. Additionally, experimental studies were performed focussing on the geometry of laparoscopy and new training concepts such as perfused pelvitrainers and computer simulation. Three-dimensional systems have not yet proved to be effective due to handling problems such as shutter glasses, video helmets, or reduced brightness. At present, there are only two robotic surgical systems (ZEUS, da Vinci) in clinical use for telesurgery, of which only the da Vinci provides stereovision and all 6 degrees of freedom (DOF). In the meantime, more than 100 laparoscopic radical prostatectomies have been performed with this system. However, there was no evidence of any advantages over the conventional laparoscopic approach. The ZEUS in combination with the telecommunication system SOKRATES is the only device that enables telemanipulation and telementoring over long distances (i.e., transatlantic). Robotic surgery represents a turning point in surgical research. However, broad use of robotic systems is limited mainly because of high investment and running costs. Whereas audiovisual telementoring will play a clear role in future training concepts, the need for telemanipulation or telesurgery has not yet been clarified.

Computer Simulation↗
PubMed1991

Range of motion in total knee arthroplasty. A computer analysis.

A three-dimensional computer model of the knee was formulated based on sectional and coordinate data from knee specimens. The model was consistent with published data in terms of contact points and ligament length patterns. Prosthetic components were designed, and surgical placement was simulated. Maximum flexion was limited by tension in the posterior cruciate ligament. Increased dishing of the tibial surface reduced flexion, but some dishing was considered necessary for reduction of contact stresses. Anteroposterior translation of the tibial component had little effect on flexion. Femoral translation had some offset, and posterior positioning reduced flexion. The most important surgical variable was tibial component tilt in the sagittal plane. Posterior tilt increased motion, while anterior tilt decreased motion. The results apply to the choice of total knee system, instrument design, and surgical technique.

Computer Simulation↗
PubMed2006

Virtual cystoscopy--a surgical planning and guidance tool.

Image guided-surgery systems facilitates surgical planning phases of endoscopic procedures. In this paper, we used a software package for 3D surface model generation and vizualization of the urinary bladder, based on magnetic resonance (MR) cross sectional images of the pelvis. The patients group consisted in 6 patients diagnosed with urinary bladder tumour. They were submitted to MRI exam. Twelve consecutive cross sectional images of the pelvis were aquired (TR (repetition time) = 600 msec, TE (echo time) = 19 msec, slice thickness = 6 divided by 7 mm, FOV (field of view) = 36 cm. All these images were transferred to a personal computer running the 3DSlicer software. We obtained, for each patient, a 3D model of the pelvis including the urinary bladder. In This way, the surgical enviroment was simulated and we are able to investigate the bladder by virtual cystoscopy. The virtual endoscopy may be used as a tool in the preoperative training and in surgical planning.

Cystoscopy↗
PubMed1996

A haptic interface for virtual simulation of endoscopic surgery.

Virtual reality can be described as a convincingly realistic and naturally interactive simulation in which the user is given a first person illusion of being immersed within a computer generated environment While virtual reality systems offer great potential to reduce the cost and increase the quality of medical training, many technical challenges must be overcome before such simulation platforms offer effective alternatives to more traditional training means. A primary challenge in developing effective virtual reality systems is designing the human interface hardware which allows rich sensory information to be presented to users in natural ways. When simulating a given manual procedure, task specific human interface requirements dictate task specific human interface hardware. The following paper explores the design of human interface hardware that satisfies the task specific requirements of virtual reality simulation of Endoscopic surgical procedures. Design parameters were derived through direct cadaver studies and interviews with surgeons. Final hardware design is presented.

Computer Simulation↗
PubMed2006

Virtual reality simulation of fluoroscopic navigation.

Surgical navigation systems assist surgeons by tracking targets attached to the patient's bones and to the surgical tools. Fluoroscopic navigation is a technology that adds "live" imaging to surgical navigation. In order to identify the limitations and potential sources of errors in fluoroscopic navigation, a virtual environment is created in which all the key steps of fluoroscopic navigation can be rehearsed. This provides a low-cost, highly portable, and radiation-free training environment with the ability of instant accuracy validation and reliable measurement of trainee progress. This virtual environment also is suitable for comparing different fluoroscopic registration techniques and protocols. Although the imaging component of the navigation is simulated, physical interaction with the environment can be modeled at different levels; from a fully virtual environment, to miniature models, to life-size dummies and cadavers. Each of these options satisfies different specific training needs, such as the need for portability and easy setup to the need for a completely realistic simulation of the entire clinical environment and operating procedure. In this study, we present the example of a system based on a scaled-down model with a specific focus on analyzing and training bony landmark localization using fluoroscopic navigation.

Computer Simulation↗
PubMed1995

Functional image-guided neurosurgical simulation system using computerized three-dimensional graphics and dipole tracing.

This report describes a preoperative simulation and intraoperative localization system for use with three-dimensional functional images in intracranial surgery. The system, which produces three-dimensional functional images by superimposition of the generators of somatosensory evoked potentials derived from dipole tracing, was applied in the preoperative localization of central sulci in 12 patients with intracranial disorders. The preoperative localization of central sulci was assessed by intraoperative cortical recording of somatosensory evoked potentials in three patients. In six patients, three-dimensional computer graphics were reconstructed from magnetic resonance images and allowed visualization of the lesions through the semitransparent views of the scalp surface and the brain. The three-dimensional functional images were created by superimposing the generators of somatosensory evoked potentials on three-dimensional computer graphics. This combined technique provided preoperative data regarding the three-dimensional relationship between the sensorimotor cortex and the lesions. We also developed a three-dimensional digitizer that incorporates a mechanical arm and a laser pointer for use in integrating information obtained in the preoperative simulation into the surgical field. Intraoperative localization can be performed in real time on the three-dimensional computer graphics in combination with the functional images created from dipole tracing. This system was applied in five patients who underwent surgical brain tumor resections with minimal damage to the normal brain tissue. The use of this system for stereotactic craniotomy increased the safety of the surgery by affording preoperative simulation and intraoperative localization with the three-dimensional functional images. Two illustrative case reports are presented.

Brain Diseases↗
PubMed2006

Simulation of surgery for craniosynostosis: a training model in a fresh cadaveric sheep cranium. Technical note.

The authors present a training model in sheep crania that allows residents in neurosurgery and plastic surgery to practice the frontoorbital remodeling procedure used in the surgical correction of simple craniosynostoses such as plagiocephaly, trigonocephaly, and brachiocephaly. The model comprises a three-step approach: subperiosteal and subperiorbital dissection; elevation of the bifrontal bone flap and the supraorbital bar; and finally, frontoorbital remodeling. The authors conclude that this training model, based on the use of cadaveric sheep crania, represents a fairly useful method to accustom trainees to the required surgical techniques and simulates well the steps of standard pediatric and adult craniofacial surgery for simple craniosynostosis.

Animals↗
PubMed1993

Concept of simulation surgery.

The concept of simulation surgery was first proposed by Fujino in 1989 and reinforced in 1991. It is divided in two sections; empirical simulation surgery, where the surgical procedure is designed first in the surgeon's brain, and computer simulation surgery, where the disease condition and the possible surgical procedures can be viewed in three-dimensions (3D) either on a computer monitor, or by means of a solid 3D model, crafted from computer generated data, before proceeding to the actual surgery itself. Each of these sections is subdivided into three subsections; morphological, functional and psychological simulation surgery, respectively. Along those lines, the concept of simulation surgery is discussed, with special reference to plastic and reconstructive surgery.

Computer Simulation↗
PubMed2005

Simulation of the biomechanical behavior of the skin in virtual surgical applications by finite element method.

The objective of this study was to develop a software application that is able to support plastic surgeons interested in applying simulations and soft tissue modeling during presurgical planning activities. By using our user-friendly interface and force-displacement graphs, users can analyze scalp skin behaviors when subjected to stress. Users can 1) determine the dynamic of a general point of scalp skin after the application of a specific force, 2) predict the force needed for displacement of a point, and 3) study the deformation of all the points of the entire scalp based on the force applied. Results showed how users are able to manipulate and analyze mechanical behaviors on a mechanical model rather than on a pure geometric qualitative physiological model. The entire application was developed on a Silicon Graphics workstation.

Animals↗