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Yu P, Zhao Z, Wang R, Pan J. Real-time soft body dissection simulation with parallelized graph-based shape matching on GPU. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 250:108171. [PMID: 38631128 DOI: 10.1016/j.cmpb.2024.108171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 04/08/2024] [Accepted: 04/08/2024] [Indexed: 04/19/2024]
Abstract
BACKGROUND AND OBJECTIVE Interactive soft tissue dissection has been a fundamental procedure in virtual surgery systems. Existing cutting algorithms involve complex topology changes of simulation meshes, which can increase simulation overhead and produce visual artifacts. In this paper, we proposed a novel graph-based shape-matching method that allows for real-time, flexible, progressive, and discontinuous cuts on soft tissue. METHODS We employed shape-matching constraints within the position-based dynamics (PBD) framework, a widely adopted approach for real-time simulation applications. The soft tissue was effectively modeled using overlapping clusters, each governed by shape-matching constraints. The dissection process was bifurcated into two distinct stages. In the first stage, the surgical scalpel presses the surface of the soft tissue. The soft tissue is cut apart when the surface pressure exceeds a threshold, entering the second stage. To address the discrepancy between the visual mesh and the simulation model during cluster separation, we developed an Aggregate Finding Connected Components (AFCC) algorithm, optimized for GPU computation and integrated with a background grid. This approach also avoids ghost forces and fragmentation artifacts. To control the increase in the number of clusters, we also propose a merging strategy that can run in parallel. RESULTS Our simulation outcomes demonstrated that the AFCC dissection algorithm effectively manages cluster separation and expansion with robustness. There were no ghost forces between the cutting surface and unrealistic fragments. Our simulation capability extended to supporting intricate and discontinuous cutting routes. Our dissection simulation maintained real-time performance even with over 100,000 particles constituting the soft tissue. CONCLUSIONS Our real-time and robust surgical dissection simulation technique enables the performance of complex cuts in various surgical scenarios, demonstrating its potential in virtual surgery applications.
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Affiliation(s)
- Peng Yu
- State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing, China
| | - Zhiyuan Zhao
- State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing, China
| | - Ruiqi Wang
- State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing, China
| | - Junjun Pan
- State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing, China.
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To G, Hawke JA, Larkins K, Burke G, Costello DM, Warrier S, Mohan H, Heriot A. A systematic review of the application of 3D-printed models to colorectal surgical training. Tech Coloproctol 2023; 27:257-270. [PMID: 36738361 DOI: 10.1007/s10151-023-02757-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 01/22/2023] [Indexed: 02/05/2023]
Abstract
BACKGROUND The aim of this review was to explore the role of three-dimensional (3D) printing in colorectal surgical education and procedural simulation, and to assess the effectiveness of 3D-printed models in anatomic and operative education in colorectal surgery. METHODS A systematic review of the literature was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify relevant publications relating to the use of 3D-printed models in colorectal surgery in an educational context. The search encompassed OVID Medline, Web of Science and EMBASE including papers in English published from 1 January 1995 to 1 January 2023. A total of 1018 publications were screened, and 5 met the criteria for inclusion in this review. RESULTS Four distinct 3D models were described across five studies. Two models demonstrated objective benefits in the use of 3D-printed models in anatomical education in academic outcomes at all levels of learner medical experience and were well accepted by learners. One model utilised for preoperative visualisation demonstrated improved operative outcomes in complete mesocolic excision compared with preoperative imaging review, with a 22.1% reduction in operative time (p < 0.001), 9.2% reduction in surgical duration (p = 0.035) and 37.3% reduction in intraoperative bleeding volume amongst novice surgeons (p < 0.01). Technical simulation has been demonstrated in a feasibility context in one model but remains limited in scope and application on account of the characteristics of available printing materials. CONCLUSIONS 3D printing is well accepted and effective for anatomic education and preoperative procedural planning amongst colorectal surgeons, trainees and medical students but remains a technology in the early stages of its possible application. Technological advancements are required to improve the tissue realism of 3D-printed organ models to achieve greater fidelity and provide realistic colorectal surgical simulations.
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Affiliation(s)
- Gloria To
- The University of Melbourne, Parkville, VIC, Australia
| | - Justin A Hawke
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Melbourne, VIC, Australia.
| | - Kirsten Larkins
- The University of Melbourne, Parkville, VIC, Australia
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Melbourne, VIC, Australia
| | - Grace Burke
- International Medical Robotics Academy, North Melbourne, VIC, Australia
| | | | - Satish Warrier
- The University of Melbourne, Parkville, VIC, Australia
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Melbourne, VIC, Australia
- International Medical Robotics Academy, North Melbourne, VIC, Australia
| | - Helen Mohan
- The University of Melbourne, Parkville, VIC, Australia
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Melbourne, VIC, Australia
| | - Alexander Heriot
- The University of Melbourne, Parkville, VIC, Australia
- Division of Cancer Surgery, Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Melbourne, VIC, Australia
- International Medical Robotics Academy, North Melbourne, VIC, Australia
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Sankaranarayanan G, Parker L, De S, Kapadia M, Fichera A. Simulation for Colorectal Surgery. J Laparoendosc Adv Surg Tech A 2021; 31:566-569. [PMID: 33891496 DOI: 10.1089/lap.2021.0096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Introduction: Colorectal surgery is a highly specialized field in surgery that deals with the surgical intervention of disease processes of the colon, rectum, and anus. Gaining proficiency in this field requires training both inside and outside of the operating room. Simulation plays a key role in training surgeons in colorectal surgery. The goal of this study is to review the currently available simulators for training in the field of colorectal surgery. Methods: A review of the literature was conducted to identify simulators that are both physical such as benchtop, live animal, and cadaver, as wells as virtual reality (VR) simulators. Any reported validity evidence for these simulators were also presented. Results: There are several benchtop physical models made of silicone for training in basic colorectal tasks, such as hand-sewn and stapled anastomosis. To improve realism, explanted animal and cadaveric specimens were also used for training. To improve repeatability, objective assessment, both commercial and VR simulators also exist for training in both open and laparoscopic colorectal surgery and emerging areas such as endoscopic submucosal dissection. Conclusion: Simulation-based training in colorectal surgery is here to stay and is going to play a significant role in training, credentialing, and quality improvements.
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Affiliation(s)
- Ganesh Sankaranarayanan
- Department of Surgery, Center for Evidence Based Simulation, Baylor University Medical Center, Dallas, Texas, USA
| | - Lisa Parker
- Division of Colon and Rectal Surgery, Department of Surgery, Baylor University Medical Center, Dallas, Texas, USA
| | - Suvranu De
- Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Muneera Kapadia
- Division of Gastrointestinal Surgery, Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Alessandro Fichera
- Division of Colon and Rectal Surgery, Department of Surgery, Baylor University Medical Center, Dallas, Texas, USA
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Kuok CP, Yang TH, Tsai BS, Jou IM, Horng MH, Su FC, Sun YN. Segmentation of finger tendon and synovial sheath in ultrasound image using deep convolutional neural network. Biomed Eng Online 2020; 19:24. [PMID: 32321523 PMCID: PMC7178953 DOI: 10.1186/s12938-020-00768-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 04/11/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Trigger finger is a common hand disease, which is caused by a mismatch in diameter between the tendon and the pulley. Ultrasound images are typically used to diagnose this disease, which are also used to guide surgical treatment. However, background noise and unclear tissue boundaries in the images increase the difficulty of the process. To overcome these problems, a computer-aided tool for the identification of finger tissue is needed. RESULTS Two datasets were used for evaluation: one comprised different cases of individual images and another consisting of eight groups of continuous images. Regarding result similarity and contour smoothness, our proposed deeply supervised dilated fully convolutional DenseNet (D2FC-DN) is better than ATASM (the state-of-art segmentation method) and representative CNN methods. As a practical application, our proposed method can be used to build a tendon and synovial sheath model that can be used in a training system for ultrasound-guided trigger finger surgery. CONCLUSION We proposed a D2FC-DN for finger tendon and synovial sheath segmentation in ultrasound images. The segmentation results were remarkably accurate for two datasets. It can be applied to assist the diagnosis of trigger finger by highlighting the tissues and generate models for surgical training systems in the future. METHODS We propose a novel finger tendon segmentation method for use with ultrasound images that can also be used for synovial sheath segmentation that yields a more complete description for analysis. In this study, a hybrid of effective convolutional neural network techniques are applied, resulting in a deeply supervised dilated fully convolutional DenseNet (D2FC-DN), which displayed excellent segmentation performance on the tendon and synovial sheath.
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Affiliation(s)
- Chan-Pang Kuok
- Department of Computer Science and Information Engineering, 1 University Road, Tainan, 701, Taiwan
- MOST AI Biomedical Research Center, 1 University Road, Tainan, 701, Taiwan
| | - Tai-Hua Yang
- Department of Biomedical Engineering, National Cheng Kung University, 1 University Road, Tainan, 701, Taiwan
- Department of Orthopaedic Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 1 University Road, Tainan, Taiwan
- Medical Device Innovation Center, National Cheng Kung University, 1 University Road, Tainan, 701, Taiwan
| | - Bo-Siang Tsai
- Department of Computer Science and Information Engineering, 1 University Road, Tainan, 701, Taiwan
| | - I-Ming Jou
- Department of Orthopedics, E-Da Hospital, 1 Yida Road, Jiaosu Village, Yanchao District, Kaohsiung City, 82445, Taiwan
| | - Ming-Huwi Horng
- Department of Computer Science and Information Engineering, National Pingtung University, 4-18 Minsheng Road, Pingtung City, Pingtung County, 90003, Taiwan
- MOST AI Biomedical Research Center, 1 University Road, Tainan, 701, Taiwan
| | - Fong-Chin Su
- Department of Biomedical Engineering, National Cheng Kung University, 1 University Road, Tainan, 701, Taiwan
| | - Yung-Nien Sun
- Department of Computer Science and Information Engineering, 1 University Road, Tainan, 701, Taiwan.
- MOST AI Biomedical Research Center, 1 University Road, Tainan, 701, Taiwan.
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Yu D, Liu C, Wu Y, An Q. Measurement and prediction of drilling force in fresh human cadaver mandibles: A pilot study. Clin Implant Dent Relat Res 2019; 22:4-12. [PMID: 31797556 DOI: 10.1111/cid.12841] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 05/29/2019] [Accepted: 08/09/2019] [Indexed: 12/27/2022]
Abstract
BACKGROUND Bone drilling is a vital procedure in implant surgery and dental implant training systems based on virtual reality technology. PURPOSE Predict and update drilling force in real time based on a virtual dental implant training system and lay the foundation for realizing force feedback in dental implant training instruments. MATERIALS AND METHODS An experimental platform was established to measure the drilling force for human mandibles from donors of different ages. Response surface methodology was applied to analyze the drilling force. RESULTS Force regression equations for different age groups were acquired. The order of the effects (from greatest to least) of the drilling parameters on the drilling force was the drill bit diameter, feed rate, and rotational speed. To obtain the minimum force, higher rotational speeds, lower feed rates, and smaller diameters were preferred within the range of commonly used medical reference parameters of bone drilling. CONCLUSION The experimental data were confirmed to be scientific for the predicted models of drilling force.
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Affiliation(s)
- Dedong Yu
- Department of 2nd Dental Center, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Chang Liu
- Institute of Manufacturing Technology and Equipment Automation, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yiqun Wu
- Department of 2nd Dental Center, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China
| | - Qinglong An
- Institute of Manufacturing Technology and Equipment Automation, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
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Gaitanidis A, Simopoulos C, Pitiakoudis M. What to consider when designing a laparoscopic colorectal training curriculum: a review of the literature. Tech Coloproctol 2018; 22:151-160. [PMID: 29512045 DOI: 10.1007/s10151-018-1760-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 12/03/2017] [Indexed: 12/27/2022]
Abstract
Multiple studies have demonstrated the benefits of laparoscopic colorectal surgery (LCS), but in several countries it has still not been widely adopted. LCS training is associated with several challenges, such as patient safety concerns and a steep learning curve. Current evidence may facilitate designing of efficient training curricula to overcome these challenges. Basic training with virtual reality simulators has witnessed meteoric advances and may be essential during the early parts of the learning curve. Cadaveric and animal model training still constitutes an indispensable training tool, due to a higher degree of difficulty and greater resemblance to real operative conditions. In addition, recent evidence favors the use of novel training paradigms, such as proficiency-based training, case selection and modular training. This review summarizes the recent advances in LCS training and provides the evidence for designing an efficient training curriculum to overcome the challenges of LCS training.
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Affiliation(s)
- A Gaitanidis
- Second Department of Surgery, University General Hospital of Alexandroupoli, Democritus University of Thrace Medical School, 68100, Alexandroupoli, Greece.
| | - C Simopoulos
- Second Department of Surgery, University General Hospital of Alexandroupoli, Democritus University of Thrace Medical School, 68100, Alexandroupoli, Greece
| | - M Pitiakoudis
- Second Department of Surgery, University General Hospital of Alexandroupoli, Democritus University of Thrace Medical School, 68100, Alexandroupoli, Greece
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Amirabdollahian F, Livatino S, Vahedi B, Gudipati R, Sheen P, Gawrie-Mohan S, Vasdev N. Prevalence of haptic feedback in robot-mediated surgery: a systematic review of literature. J Robot Surg 2017; 12:11-25. [PMID: 29196867 DOI: 10.1007/s11701-017-0763-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/07/2017] [Indexed: 01/27/2023]
Abstract
With the successful uptake and inclusion of robotic systems in minimally invasive surgery and with the increasing application of robotic surgery (RS) in numerous surgical specialities worldwide, there is now a need to develop and enhance the technology further. One such improvement is the implementation and amalgamation of haptic feedback technology into RS which will permit the operating surgeon on the console to receive haptic information on the type of tissue being operated on. The main advantage of using this is to allow the operating surgeon to feel and control the amount of force applied to different tissues during surgery thus minimising the risk of tissue damage due to both the direct and indirect effects of excessive tissue force or tension being applied during RS. We performed a two-rater systematic review to identify the latest developments and potential avenues of improving technology in the application and implementation of haptic feedback technology to the operating surgeon on the console during RS. This review provides a summary of technological enhancements in RS, considering different stages of work, from proof of concept to cadaver tissue testing, surgery in animals, and finally real implementation in surgical practice. We identify that at the time of this review, while there is a unanimous agreement regarding need for haptic and tactile feedback, there are no solutions or products available that address this need. There is a scope and need for new developments in haptic augmentation for robot-mediated surgery with the aim of improving patient care and robotic surgical technology further.
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Affiliation(s)
| | - Salvatore Livatino
- School of Engineering, University of Hertfordshire, Hatfield, AL10 9AB, UK
| | - Behrad Vahedi
- School of Engineering, University of Hertfordshire, Hatfield, AL10 9AB, UK
| | - Radhika Gudipati
- School of Computer Science, University of Hertfordshire, Hatfield, AL10 9AB, UK
| | - Patrick Sheen
- School of Engineering, University of Hertfordshire, Hatfield, AL10 9AB, UK
| | | | - Nikhil Vasdev
- Department of Urology, Hertfordshire and Bedfordshire Urological Cancer Centre, Lister Hospital, Stevenage, SG1 4AB, UK.,School of Life and Medical Sciences, University of Hertfordshire, Hatfield, Hertfordshire, AL10 9AB, UK
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Pan JJ, Ahn W, Dargar S, Halic T, Li BC, Sankaranarayanan G, Roberts K, Schwaitzberg S, De S. Graphic and haptic simulation for transvaginal cholecystectomy training in NOTES. J Biomed Inform 2016; 60:410-21. [PMID: 26980236 DOI: 10.1016/j.jbi.2016.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/19/2016] [Accepted: 03/04/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND Natural Orifice Transluminal Endoscopic Surgery (NOTES) provides an emerging surgical technique which usually needs a long learning curve for surgeons. Virtual reality (VR) medical simulators with vision and haptic feedback can usually offer an efficient and cost-effective alternative without risk to the traditional training approaches. Under this motivation, we developed the first virtual reality simulator for transvaginal cholecystectomy in NOTES (VTEST™). METHODS This VR-based surgical simulator aims to simulate the hybrid NOTES of cholecystectomy. We use a 6DOF haptic device and a tracking sensor to construct the core hardware component of simulator. For software, an innovative approach based on the inner-spheres is presented to deform the organs in real time. To handle the frequent collision between soft tissue and surgical instruments, an adaptive collision detection method based on GPU is designed and implemented. To give a realistic visual performance of gallbladder fat tissue removal by cautery hook, a multi-layer hexahedral model is presented to simulate the electric dissection of fat tissue. RESULTS From the experimental results, trainees can operate in real time with high degree of stability and fidelity. A preliminary study was also performed to evaluate the realism and the usefulness of this hybrid NOTES simulator. CONCLUSIONS This prototyped simulation system has been verified by surgeons through a pilot study. Some items of its visual performance and the utility were rated fairly high by the participants during testing. It exhibits the potential to improve the surgical skills of trainee and effectively shorten their learning curve.
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Affiliation(s)
- Jun J Pan
- State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, Beijing, China; Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA.
| | - Woojin Ahn
- Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA
| | - Saurabh Dargar
- Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA
| | - Tansel Halic
- Computer Science Department, University of Central Arkansas, Conway, USA
| | - Bai C Li
- Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA
| | - Ganesh Sankaranarayanan
- Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA
| | - Kurt Roberts
- Gastrointestinal Surgery, Yale School of Medicine, Yale University, New Heaven, USA
| | - Steven Schwaitzberg
- Department of Surgery, Cambridge Health Alliance, Harvard Medical School, Boston, USA
| | - Suvranu De
- Center for Modeling, Simulation and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, USA
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Beyer-Berjot L, Palter V, Grantcharov T, Aggarwal R. Advanced training in laparoscopic abdominal surgery: a systematic review. Surgery 2014; 156:676-88. [PMID: 24947643 DOI: 10.1016/j.surg.2014.04.044] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 04/18/2014] [Indexed: 01/08/2023]
Abstract
BACKGROUND Simulation has spread widely this last decade, especially in laparoscopic surgery, and training out of the operating room has proven its positive impact on basic skills during real laparoscopic procedures. Few articles dealing with advanced training in laparoscopic abdominal surgery, however, have been published. Such training may decrease learning curves in the operating room for junior surgeons with limited access to complex laparoscopic procedures as a primary operator. METHODS Two reviewers, using MEDLINE, EMBASE, and The Cochrane Library conducted a systematic research with combinations of the following keywords: (teaching OR education OR computer simulation) AND laparoscopy AND (gastric OR stomach OR colorectal OR colon OR rectum OR small bowel OR liver OR spleen OR pancreas OR advanced surgery OR advanced procedure OR complex procedure). Additional studies were searched in the reference lists of all included articles. RESULTS Fifty-four original studies were retrieved. Their level of evidence was low: most of the studies were case series and one fifth were purely descriptive, but there were eight randomized trials. Pig models and video trainers as well as gastric and colorectal procedures were mainly assessed. The retrieved studies showed some encouraging trends in terms of trainee satisfaction with improvement after training, but the improvements were mainly on the training tool itself. Some tools have been proven to be construct-valid. CONCLUSION Higher-quality studies are required to appraise educational value in this field.
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Affiliation(s)
- Laura Beyer-Berjot
- Division of Surgery, Department of Surgery and Cancer, St. Mary's Campus, Imperial College Healthcare NHS Trust, London, UK; Center for Surgical Teaching and Research (CERC), Aix-Marseille Université, Marseille, France.
| | - Vanessa Palter
- Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Teodor Grantcharov
- Department of Surgery, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Rajesh Aggarwal
- Division of Surgery, Department of Surgery and Cancer, St. Mary's Campus, Imperial College Healthcare NHS Trust, London, UK; Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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