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Jeong J, Park M, Son D. Effects of lesion size, shape, and resection amount on the final length of the scar in staged excision: An animal experiment in pigs. ARCHIVES OF AESTHETIC PLASTIC SURGERY 2020. [DOI: 10.14730/aaps.2020.02054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Capek L, Flynn C, Molitor M, Chong S, Henys P. Graft orientation influences meshing ratio. Burns 2018; 44:1439-1445. [PMID: 29861098 DOI: 10.1016/j.burns.2018.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/17/2018] [Accepted: 05/07/2018] [Indexed: 10/14/2022]
Abstract
OBJECTIVES The technique of meshed skin grafting is known since 1960s. It was shown that there is a difference between the declared and real expansion ratio of the skin meshed graft. We hypothesize that the orientation of the Langer's lines in a split thickness skin graft is a key parameter in the resulting expansion ratio. METHODS The skin graft meshing process was analyzed in two steps. In the first step, ex vivo uniaxial tests of human skin were performed. This served as an input for the constitutive model used for numerical simulations. In the second step, finite element analyses were performed so that stress distributions and expansion ratios could be determined. RESULTS It was shown that peaks of true stress tended to be concentrated around the vertex of the mesh pattern region for all cases. The declared expansion was impossible to obtain for all expansion ratios having the meshing incision perpendicular to the Langer's lines. The highest difference between declared and real expansion ratio reaches 37%. CONCLUSIONS With regard to literature dealing with expansion of skin grafts by meshing, a high scatter amongst data results is observed. This finding was also explained by our research, demonstrating the significance of Langer's lines and their relative orientation to the direction of meshing.
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Affiliation(s)
- Lukas Capek
- Technical University of Liberec, Department of Structure and Technologies, Studentska 2, 46117 Liberec 1, Czech Republic
| | - Cormac Flynn
- Waikato Institute of Technology, Private Bag 3036, Hamilton 3240, New Zealand
| | - Martin Molitor
- University Hospital Bulovka, Department of Plastic Surgery, Budinova 8, Prague, Czech Republic
| | - Simon Chong
- Anglesea Hospital, Department of Plastic & Reconstructive Surgery, 19 Knox St, Hamilton, New Zealand
| | - Petr Henys
- Technical University of Liberec, Department of Structure and Technologies, Studentska 2, 46117 Liberec 1, Czech Republic.
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Chanda A, Ruchti T, Unnikrishnan V. Computational Modeling of Wound Suture: A Review. IEEE Rev Biomed Eng 2018; 11:165-176. [DOI: 10.1109/rbme.2018.2804219] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Karanasiou GS, Gatsios DA, Lykissas MG, Stefanou KA, Rigas GA, Lagaris IE, Kostas-Agnantis IP, Gkiatas I, Beris AE, Fotiadis DI. Modeling of blood flow through sutured micro-vascular anastomoses. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:1877-80. [PMID: 26736648 DOI: 10.1109/embc.2015.7318748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Microanastomosis is a surgical procedure used to reconnect two blood vessels using sutures. The optimal microanastomosis may be predicted by assessing the factors that influence this invasive procedure. Blood flow and hemodynamics following microanastomosis are important factors for the successful longevity of this operation. How is the blood flow affected by the presence of sutures? Computational Fluid Dynamics (CFD) is a powerful tool that permits the estimation of specific quantities, such as fluid stresses, that are hardly measurable in vivo. In this study, we propose a methodology which evaluates the alterations in the hemodynamic status due to microanastomosis. A CFD model of a reconstructed artery has been developed, based on anatomical information provided by intravascular ultrasound and angiography, and was used to simulate blood flow after microanastomosis. The 3D reconstructed arterial segments are modeled as non-compliant 1.24 - 1.47 mm diameter ducts, with approximately 0.1 mm arterial thickness. The blood flow is considered laminar and the no-slip condition is imposed on the boundary wall, which is assumed to be rigid. In analyzing the results, the distribution of the wall shear stress (WSS) is presented in the region of interest, near the sutures. The results indicate that high values of WSS appear in the vicinity of sutures. Such regions may promote thrombus formation and subsequently anastomotic failure, therefore their meticulous study is of high importance.
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Mathematical models of wound healing and closure: a comprehensive review. Med Biol Eng Comput 2015; 54:1297-316. [DOI: 10.1007/s11517-015-1435-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
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Topp SG, Lovald S, Khraishi T, Gaball CW. Biomechanics of the Rhombic Transposition Flap. Otolaryngol Head Neck Surg 2014; 151:952-9. [DOI: 10.1177/0194599814551128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective To develop a computational model of cutaneous wound closures comparing variations of the rhombic transposition flap. Study Design A nonlinear hyperelastic finite element model of human skin was developed and used to assess flap biomechanics in simulated rhombic flap wound closures as flap geometric parameters were varied. Setting In silico. Methods The simulation incorporated variables of transposition angle, flap width, and tissue undermining. A 2-dimensional second-order Yeoh hyperelastic model was fit to published experimental skin data. Resultant stress and strain fields as well as local surface changes were evaluated. Results For the rhombus defect, closure stress and strain were minimized for the transposition flap with a distal flap angle of 30° by recruiting skin from opposing sides of the defect. Alteration of defect dimensions showed that peak stress and principal strain were minimized with a square defect. Likelihood of a standing cutaneous deformity was driven by the magnitude of angle closure at the flap base. Manipulation of the transposition angle reoriented the primary skin strain vector. Asymmetric undermining decoupled wound closure tension from strain, with direct effects on boundary deformation. Conclusions The model demonstrates that flap width determines the degree of secondary tissue movement and impact on surrounding tissues. Transposition angle determines the orientation of maximal strain. Local flap design requires consideration of multiple factors apart from idealized biomechanics, including adjacent “immobile” structures, scar location, local skin thickness, and orientation of relaxed skin tension lines. Finite element models can be used to analyze local flap closures to optimize outcomes.
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Affiliation(s)
- Shelby G. Topp
- Naval Medical Center, San Diego, Department of Otolaryngology, San Diego, California, USA
| | - Scott Lovald
- Exponent, Incorporated, Menlo Park, California, USA
| | - Tariq Khraishi
- University of New Mexico Mechanical Engineering Department, Albuquerque, New Mexico, USA
| | - Curtis W. Gaball
- Naval Medical Center, San Diego, Department of Otolaryngology, San Diego, California, USA
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Abstract
INTRODUCTION We compared the results of our computer simulation studies of Z-plasties of different design to those of earlier studies, such as laboratory studies in dogs. MATERIAL AND METHODS The contours of single Z-plasties of different designs on flat surfaces were transferred to finite element analytical software (ADINA version 8.7). RESULTS The lengthening effect was almost proportional to the size of the Z-plasty, but was always less than what was predicted by geometric calculation. The percent gain in length decreased with the number of Z-plasties. CONCLUSION We used ADINA software analyze the lengthening effects of Z-plasties of different patterns. Our results support those of earlier experiments and should help increase our understanding of Z-plasties of various patterns.
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Affiliation(s)
- Erika Kitta
- Department of Plastic and Reconstructive Surgery, Nippon Medical School Chiba Hokusoh Hospital, Japan
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Jor JWY, Parker MD, Taberner AJ, Nash MP, Nielsen PMF. Computational and experimental characterization of skin mechanics: identifying current challenges and future directions. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 5:539-56. [PMID: 23757148 DOI: 10.1002/wsbm.1228] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/25/2013] [Accepted: 04/26/2013] [Indexed: 12/21/2022]
Abstract
The characterization of skin mechanics has many clinical implications and has been an active area of research for the past few decades. Biomechanical models have evolved from earlier empirical models to state-of-the-art structural models that provide linkage between tissue microstructure and macroscopic stress-strain response. To maximize the accuracy and predictive capabilities of such computational models, there is a need to reliably identify often a large number of unknown model parameters. This is critically dependent on the availability of experimental data that cover an extensive range of different deformation modes, and quantification of internal structural features, such as collagen orientation. To this end, future challenges should include the ongoing development of noninvasive instrumentation and imaging modalities for in vivo skin measurements. We highlight the important concept of tightly integrating computational models, instrumentation, and imaging modalities into a single platform to investigate skin biomechanics.
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Affiliation(s)
- Jessica W Y Jor
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Capek L, Jacquet E, Dzan L, Simunek A. The analysis of forces needed for the suturing of elliptical skin wounds. Med Biol Eng Comput 2011; 50:193-8. [PMID: 22201040 DOI: 10.1007/s11517-011-0857-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 12/12/2011] [Indexed: 01/30/2023]
Abstract
There is a lack of information regarding the forces required for suturing human wounds. The knowledge of suturing forces serves as complementary information for setting up the limiting geometry when using tissue adhesives and it might also be used in robot-assisted surgery. The main purpose of this paper was to evaluate the forces required for suturing selected skin wounds. An elliptical wound was chosen for our study. In this study a numerical analysis and in vivo experiments were performed. Regarding the numerical models, the maximum forces occurred in the middle of the elliptical wound in all cases. In the case of highest pre-stress used in these analyses the maximal force varied from 0.5 N for the smallest wound (30 × 5 mm) to 1.5 N for the largest wound (30 × 15 mm). The maximum peak force for the wound with a size of 46 × 13 mm was 3.2 N. The minimum peak force for the wound with a size of 36 × 5 mm was 1.1 N.
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Affiliation(s)
- Lukas Capek
- Department of Applied Mechanics, Technical University of Liberec, Studentska 2, 46117 Liberec, Czech Republic.
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Flynn C. Finite element models of wound closure. J Tissue Viability 2010; 19:137-49. [DOI: 10.1016/j.jtv.2009.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 10/22/2009] [Accepted: 10/22/2009] [Indexed: 10/20/2022]
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Flynn C, McCormack BA. A simplified model of scar contraction. J Biomech 2008; 41:1582-9. [DOI: 10.1016/j.jbiomech.2008.02.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 02/01/2008] [Accepted: 02/04/2008] [Indexed: 11/29/2022]
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Gambarotta L, Massabò R, Morbiducci R, Raposio E, Santi P. In vivo experimental testing and model identification of human scalp skin. J Biomech 2005; 38:2237-47. [PMID: 16154411 DOI: 10.1016/j.jbiomech.2004.09.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2002] [Accepted: 09/10/2004] [Indexed: 10/26/2022]
Abstract
A comprehensive experimental/numerical procedure is formulated and validated for the in vivo characterization of the mechanical properties of human skin and the simulation of reconstructive surgery. The procedure uses in vivo experimental tests on undermined skin flaps, which can be performed during surgery, a numerical model formulated within the framework of nonlinear finite strain elasticity and a nonlinear parameter identification technique for the calibration of the model from indirect measurements. The procedure is applied to characterize the scalp skin tested in Raposio and Nordström (Skin Res. Technol. 4 (1998) 94). The skin is treated as a time independent, isotropic and hyperelastic membrane and the problem is solved through a finite element discretization. The study highlights that the model parameters can be determined with good accuracy using displacement measurements of a few points in the domain.
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Affiliation(s)
- L Gambarotta
- Department of Structural and Geotechnical Engineering, University of Genoa, Via Montallegro 1, 16145 Genoa, Italy.
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Spicer MA, van Velsen M, Caffrey JP, Apuzzo MLJ. Virtual Reality Neurosurgery: A Simulator Blueprint. Neurosurgery 2004; 54:783-97; discussion 797-8. [PMID: 15046644 DOI: 10.1227/01.neu.0000114139.16118.f2] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2003] [Accepted: 11/18/2003] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE This article details preliminary studies undertaken to integrate the most relevant advancements across multiple disciplines in an effort to construct a highly realistic neurosurgical simulator based on a distributed computer architecture. Techniques based on modified computational modeling paradigms incorporating finite element analysis are presented, as are current and projected efforts directed toward the implementation of a novel bidirectional haptic device. METHODS Patient-specific data derived from noninvasive magnetic resonance imaging sequences are used to construct a computational model of the surgical region of interest. Magnetic resonance images of the brain may be coregistered with those obtained from magnetic resonance angiography, magnetic resonance venography, and diffusion tensor imaging to formulate models of varying anatomic complexity. RESULTS The majority of the computational burden is encountered in the presimulation reduction of the computational model and allows realization of the required threshold rates for the accurate and realistic representation of real-time visual animations. CONCLUSION Intracranial neurosurgical procedures offer an ideal testing site for the development of a totally immersive virtual reality surgical simulator when compared with the simulations required in other surgical subspecialties. The material properties of the brain as well as the typically small volumes of tissue exposed in the surgical field, coupled with techniques and strategies to minimize computational demands, provide unique opportunities for the development of such a simulator. Incorporation of real-time haptic and visual feedback is approached here and likely will be accomplished soon.
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Affiliation(s)
- Mark A Spicer
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, 1200 North State Street, Los Angeles, CA 90033, USA.
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Spicer MA, Apuzzo MLJ. Virtual reality surgery: neurosurgery and the contemporary landscape. Neurosurgery 2003; 52:489-97; discussion 496-7. [PMID: 12590672 DOI: 10.1227/01.neu.0000047812.42726.56] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2002] [Accepted: 10/31/2002] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Virtual reality-simulated environments have been used for the training of personnel, most notably for military applications, for more than 35 years. The advantages conferred by being able to train novice personnel in a low- to no-risk simulated environment have long been appreciated by the medical community. The recent availability of affordable gigahertz-range microprocessors (once the exclusive domain of the Cray supercomputer) has made photorealistic graphical rendering and manipulation of virtual surgical substrates a reality. Concomitant advances in artificial intelligence systems and the portability of patient-specific magnetic resonance imaging, computed tomographic scanning, and angiographic image data presage the emergence of the surgical simulator as a modern surgical training adjunct. An overview of the status of surgical simulation with regard to its adaptability to current surgical training regimens is presented. METHODS Extensive MEDLINE, Internet, and other database searches spanning the years 1960 to 2002 were conducted in an effort to delineate the status of simulated surgical environments. RESULTS As would be expected, most articles addressing surgical simulation as their primary focus have been published in the past decade. A review of this literature demonstrates the broadest application in the field of endoscopic (and laparoscopic) procedures, most likely as a result of the reduced engineering burden with respect to incorporation of a haptic interface. CONCLUSION The realization of ergonomically acceptable haptic interfaces remains elusive. Improvements in graphical rendering and the incorporation of artificial intelligence functions signal the certain emergence of surgical simulators as a viable supplement to the Halstedian method of surgical training.
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Affiliation(s)
- Mark A Spicer
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
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