Available online at
ScienceDirect www.sciencedirect.com Chirurgie de la main 33 (2014) 106–111
Original article
Use of the Konnyaku Shirataki noodle as a low fidelity simulation training model for microvascular surgery in the operating theatre Utilisation des nouilles « konnyaku shirataki » comme modèle d’entraînement de faible fidélité à la microchirurgie vasculaire en salle d’opération G.J.-C. Prunières a, C. Taleb a, S. Hendriks a, H. Miyamoto b, N. Kuroshima c, P.A. Liverneaux a,*, S. Facca a a
Department of hand surgery, Strasbourg university hospital, 10, avenue Baumann, 67403 Illkirch, France b Department of orthopaedics surgery, Graduate school of medicine, university of Tokyo, Tokyo, Japan c Department of orthopaedics, Teikyo university school of medicine, Tokyo, Japan Received 7 September 2013; received in revised form 1 December 2013; accepted 9 December 2013 Available online 4 February 2014
Abstract The aim of this study was to test the feasibility of a type of Japanese noodle, named ‘‘shirataki konnyaku’’, for microsurgery training in the operating room. Thirteen surgical residents without experience in microsurgery had to perform two microsurgical anastomoses: one on a model of a femoral artery of a rat (control) and one on a model of a konnyaku shirataki. Two quantitative variables (time in minutes and number of stitches to perform the anastomosis) and two qualitative variables (patency and tightness of the anastomosis) were measured. Sixty anastomoses were performed with the control model and 62 anastomoses with the konnyaku model. The time of the anatomosis was significantly higher in the control group. The number of stitches was similar in both groups. The patency of the anastomosis was significantly lower in the control group. The tightness (no leak) of the anastomosis was significantly higher in the control group. The ‘‘konnyaku shirataki’’ model could improve the teaching of microsurgery due to its availability, low cost and structural similarity to the animal model. # 2014 Elsevier Masson SAS. All rights reserved. Keywords: Microsurgery; Konnyaku shirataki; Training; Model; Rat
Résumé Le but de ce travail était de tester la faisabilité d’un modèle de nouilles japonaises « konnyaku shirataki » pour l’entraînement en microchirurgie au bloc opératoire. Treize internes en chirurgie sans expérience de microchirurgie devaient réaliser des couples d’anastomoses microchirurgicales avec un modèle d’artère fémorale de rat (témoin) et un modèle de konnyaku shirataki. Deux variables quantitatives (temps en minutes et nombre de points pour réaliser l’anastomose) et deux variables qualitatives (perméabilité et étanchéité de l’anastomose) étaient mesurées. Soixante anastomoses ont été réalisées avec le modèle témoin et 62 anastomoses avec le modèle konnyaku. Le temps d’anastomose était significativement supérieur dans le groupe témoin. Le nombre de points était identique dans les 2 groupes. La perméabilité des anastomoses était significativement inférieure dans le groupe témoin. L’étanchéité des anastomoses était significativement supérieure dans le groupe témoin. Le modèle konnyaku shirataki, par sa disponibilité, son faible coût et sa structure proche du modèle animal pourrait améliorer l’enseignement de la microchirurgie. # 2014 Elsevier Masson SAS. Tous droits réservés. Mots clés : Microchirurgie ; Konnyaku shirataki ; Entraînement ; Modèle ; Rat
* Corresponding author. E-mail address: [email protected] (P.A. Liverneaux). 1297-3203/$ – see front matter # 2014 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.main.2013.12.003
G.-C. Prunières et al. / Chirurgie de la main 33 (2014) 106–111
107
1. Introduction
2. Material and methods
Microsurgery is a cross technique used in many specialties such as plastic surgery, hand surgery, peripheral nerve surgery, ophthalmology or neurosurgery. Practical microsurgery training must be conducted in a laboratory observing international standards as it involves experimentation on animals. It requires a lot of training on virtual [1], synthetic [2,3] or biological experimental models [4,5]. These conventional models have several disadvantages: high cost, complex logistics, and low representation [6]. So far, none of these models has replaced the reference model: the rat. Some developing countries do not have laboratories with international standards. Thus, the training of young surgeons in microsurgery is done mostly overseas, in expensive workshops of short duration [7]. Back in their country of origin, these young microsurgeons encounter difficulties, not only to improve their skills, but also to continue their training [8]. To address this problem, the ideal microsurgery model should meet the following criteria: economical, readily available, and consistent with the sterile environment of the operating room and close to the anatomy of the anastomosed vessels in human microsurgery [5]. The aims of this study were:
This work was done in an accredited animal testing laboratory. The animals were acclimated for at least 2 weeks before the experiments. All procedures were approved by the local Ethics Committee and complied with the legislation on animal experimentation (Directive 2010/63/EU of the European Parliament and the Council of 22 September 2010 on the protection of animals used for scientific purposes). Thirteen surgical residents, preparing for a university degree in microsurgery, were recruited to participate in this work. Each resident was supposed to perform at least one pair of microsurgical anastomoses, one on a rat’s femoral artery model, and the second one on a konnyaku shirataki noodle model. The rat’s femoral artery model required the use of 38 adult male rats of Wistar strain with an average weight of 350 g to achieve 60 anastomoses. The rats were anesthetized by intraperitoneal injection of a solution of 1 mL/100 g ketamine and Midazolam with a maintenance dose of 1 mL every hour. The rats were put in the supine position, both inguinal regions were prepared and addressed surgically. The femoral artery was isolated on a vascular clamp (Biover1, TM Arex, Palaiseau, France), and sectioned, using microsurgical scissors. The konnyaku shirataki model required the use of 104 full noodles of 1.5 mm diameter and 20 mm length to achieve 62 anastomoses. One box contains a dozen konnyaku shirataki noodles approximately 20 cm long, for a total price of about $ 2. Each konnyaku shirataki noodle was drilled (Fig. 1) using a catheter of 0.7 mm diameter (Surflo-W1, TM Terumo Europe,
to test the feasibility of a Japanese noodle of type konnyaku shirataki by comparing the results from a series of konnyaku anastomoses to those of a rat’s femoral artery; to introduce konnyaku shirataki as a microvascular surgical training model in the operating theatre for hospitals with no microsurgical training lab facilities.
Fig. 1. Preparation of a konnyaku shirataki model. Drilling of the model to produce the lumen (A). The catheter needle in place, the konnyaku is incompletely removed to leave a length of 5 mm of lumen to allow anastomosis (B). Model ready to be anastomosed (C).
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G.-C. Prunières et al. / Chirurgie de la main 33 (2014) 106–111
Fig. 2. Anastomosis of a konnyaku Shirataki model. Penetration of a 10/0 nylon suture needle through the lumen (A). Tightening of the nylon 10/0 (B). Anastomosis completed (C).
Leuven, Belgium). Two konnyaku shirataki noodles were put next to each other, a few millimeters apart, to form an anastomosis model (Fig. 2 and Supplementary data, video). The anastomosis method was the same for both models. An end-to-end anastomosis was performed under a microscope (Wild1, TM Leica Microsystems, Heerbrugg, Switzerland) using 10/0 nylon stitches. The evaluation of the results was the same for both models. Two quantitative variables were measured: the time in minutes and the number of stitches used to perform the anastomosis. Two qualitative variables were evaluated: the patency and absence of anastomotic leak (watertightness) [9–11]. In the control model, patency and leak were evaluated by a conventional auto-fill test after emptying the distal segment of the anastomosed artery. After evaluation, the rats were killed by a lethal dose of ketamine. In the konnyaku shirataki model, patency and number of leaks were evaluated by filling the distal anastomosed segment of the konnyaku shirataki noodle with an injection of a colored product (chlorhexidine alcohol colored 0.5%, Gilbert TM, Herouville Saint Clair, France) through the proximal catheter. The statistical analysis of the four variables was carried out under the Bayesian paradigm. Time is a quantitative, continuous, Gaussian-character variable; the mixed linear regression model was chosen. Considering that the number of stitches is a positive quantitative discrete variable, the mixed regression model of Poisson was chosen. Patency and anastomosis leak being two binary variables, the Joint Logistic regression model was chosen. The significance of the results was assessed using the credible interval 95% of the mean difference in each group. Two averages could be considered
significantly different if the credibility interval of the difference did not contain the value 0. A dietary, bacteriological and fungal analysis was made through the process of maceration in a sterile bag on the konnyaku shirataki themselves (research microorganisms at 30 8C, coagulase-positive Staphylococcus, E. coli, Salmonella, Listeria monocytogenes, Moulds/yeast, Clostridium perfringens, Bacillus cereus) and on their conservation fluid (global analysis by seeding in 1 mL liquid surface on blood agar, incubated at 37 8C for 48 hours, identification of all microorganisms by mass spectrometry). The analyses were performed on day (D) 0 (day the pack was opened), on D7 and on D14. The konnyaku shirataki noodles were transferred into a biological safety cabinet with laminar air flow in a closed sterile container; one part of the noodles were kept at room temperature and another part stored in a refrigerator (5 8C 3 8C).
3. Results The results are reported in Table 1. A total of 60 anastomoses were performed using the femoral artery of the rat and 62 anastomoses using the konnyaku shirataki model. Between them, 54 pairs of microsurgical anastomoses were performed. In 6 cases, only the anastomosis of the rat femoral artery model was performed. In 8 cases, only the anastomosis with the konnyaku shirataki model was performed. Incomplete pairs of anastomoses were due to an insufficient number of shirataki konnyaku models available in some cases, and to the premature death of the rat in other cases.
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Table 1 Results of a series of 60 anastomoses performed on a rat femoral artery model and 62 anastomoses on a konnyaku shirataki model. Anastomoses (n)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
Rat femoral artery model
Konnyaku shirataki model
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
46 50 60 38 27 180 180 40 26 30 50 50 90 60 50 60 30 25 30 50 45 50 60 60 60 60 30 40 25 40 90 30 30 * 20 60 * 60 30 28 38 90 90 * 120 120 * 20 45 30 20 * * * * 60 45 50 60 60 40 60
4 5 5 5 5 6 4 4 4 6 6 6 5 4 6 6 6 4 5 7 5 5 5 5 6 4 6 9 6 4 4 4 4 * 8 4 * 6 5 6 5 5 6 * 10 7 * 5 6 6 6 * * * * 5 6 7 7 5 5 5
Y N Y N Y Y N N Y Y Y Y N Y Y Y Y Y Y N Y Y N N Y N N Y Y N Y Y Y * Y N * Y Y Y N Y Y * Y Y * Y Y Y Y * * * * Y Y Y Y Y Y N
Y Y N Y Y Y N N Y Y Y Y N N Y N Y Y Y N Y N Y N Y Y Y Y Y Y Y Y Y * Y N * Y Y N Y Y N * Y Y * Y Y Y Y * * * * Y Y Y N N Y N
30 38 30 35 36 20 50 33 43 40 40 20 34 16 10 15 20 15 35 40 15 20 60 30 60 30 25 20 15 15 * * 21 16 20 45 45 25 * 25 30 25 20 25 20 25 25 20 30 20 12 10 15 19 20 20 15 20 25 20 * 20
6 6 3 6 6 6 3 6 6 5 5 5 6 6 6 6 4 6 5 6 4 5 5 5 6 4 7 6 5 7 * * 7 6 7 5 4 5 * 6 5 6 5 6 5 7 6 4 6 6 4 4 5 6 6 5 6 8 6 5 * 6
N N N N Y N N N Y N Y N Y Y Y Y Y Y Y N Y Y N N N N Y Y N Y * * Y Y Y N N N * Y Y Y Y Y N Y Y N Y Y Y Y Y Y Y N Y N N N * Y
Y Y N Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y N Y Y Y Y Y Y Y Y Y Y * * Y Y Y Y Y Y * Y Y Y Y Y N Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y * Y
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110 Table 1 (Continued ) Anastomoses (n)
63 64 65 66 67 68
Rat femoral artery model
Konnyaku shirataki model
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
25 35 80 80 60 60
6 7 5 5 5 6
Y Y Y Y Y Y
Y Y N N Y Y
17 14 20 15 * *
7 7 5 5 * *
Y N Y N * *
Y Y Y Y * *
Y: yes. N: no. *: missing data.
The average time to perform the anastomosis in the rat femoral artery group was 54.6 minutes ( 32.5 min) versus 25.6 minutes ( 11.3 min) in the konnyaku shirataki group. The difference between the two averages was significantly non-zero, according to the parameters estimated by the mixed linear regression model, and after a Box-Cox transformation parameter of –0.27, the difference was 0.2672 [0.2121, 0, 3223]. The average number of stitches to perform the anastomosis in the rat femoral artery group was 5.48 ( 1.21) versus 5.53 ( 1.00) in the konnyaku shirataki group. The difference was not significantly different from 0, according to the mixed Poisson regression model, the difference was –0.0073 [–0.1628, 0.1471]. The patency of the anastomoses in the rat femoral artery group was positive in 69% (37/54) versus 94% (51/54) in the konnyaku shirataki group. The difference was significantly non-zero, according to the Joint Logistic regression model, the difference was 2401 [–4.040, –1.087]. The water-tightness of anastomoses in the control group was 74% (40/54) against 54% (29/54) in the konnyaku shirataki group. The difference was significantly non-zero, according to the Joint Logistic regression model, the difference was –1.463 [–2.530, –0.4855]. 4. Discussion None of the experimental models used for training in microsurgery, whether organic or not, is entirely satisfactory for regular training of surgeons who have no access to laboratory animal facilities [12]. Non-biological polyurethane models have the advantage that they can be sterilized and used in an operating room or laboratory animal facility. However, their mechanical and rheological properties are too far from those of a human or animal artery and thus cannot be considered as validation models [3]. They are used as models for introduction to microsurgery. Non-living biological models, such as chicken thigh arteries [13,14] – or more recently the worm – [6] are anatomically and physiologically more similar to human vessels. However, for regulatory reasons, they can be introduced neither in the operating room nor a laboratory animal facility. These classic models should be removed from the arsenal of training models in microsurgery. In living biological models (mainly rats) [15] delayed testing of the success of vascular anastomoses is possible. However, they
require complex and expensive logistics, which are subject to strict regulations. Many teams do not have access to a laboratory animal facility. This was the main motivation for our work. The ideal microsurgical training model for surgeons, who do not have access to animal experimentation models, must meet the following criteria: availability, cost-effectiveness, standardization, reproducing the properties of the vascular wall, and sterility. The konnyaku shirataki noodle meets these criteria. It is available in food retail at $ 2 for a 228 g-pack, good for at least 100 anastomoses. The konnyaku shirataki noodle has a constant diameter of about 1.5 mm, which corresponds to the femoral artery of a rat. Statistical analysis of the four variables was carried out under the Bayesian paradigm, thus overcoming the limits of decisions set beforehand in frequentist methods. The Bayesian paradigm is used to evaluate the probability of the hypothesis to prove, and thus refine the findings. Moreover, the use of mixed models allows comparing a couple of values in each session, or repeated measures, which significantly reduces bias in the estimates. Results comparing our two models show that the konnyaku shirataki anastomosis is very close to the anastomosis of a rat’s femoral artery. The anastomosis is faster with the konnyaku shirataki model. This can be explained by the absence of adventitia and spasm that keeps the lumen permanently open. The number of stitches required to achieve an anastomosis is identical for both models. Patency was better with the konnyaku shirataki model. This can be explained by the absence of platelet thrombi induced by any damage to the inner luminal wall. However, the watertightness was slightly worse with the konnyaku shirataki model. This can be explained by the absence of platelet plug formation. The results of bacteriological and fungal analysis show that the commercial presentation of the konnyaku shirataki is sterile at D0, D7 and D14. The Committee against nosocomial infections in our institution even allowed its introduction to the operating room. However, we recommend not keeping the konnyaku shirataki in the operating room once the package has been opened twice. 5. Conclusion The konnyaku shirataki model can be introduced in the operating room to perfect the training of junior microsurgeons who do not have access to a proper microsurgery laboratory. It also reduces the number of animals used for training purposes, but does not fully replace the reference model: the rat.
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Disclosure of interest Philippe Liverneaux has conflict of interest with Newclip Technics, Integra, Argomedical, SBI. The other authors declare that they have no conflicts of interest concerning this article. Acknowledgements Mr. Michael Schaeffer, engineer in Biostatistics, Department of Methodology and Biostatistics, University of Strasbourg, Strasbourg, France. Dr. Celine Hernandez and Dr. Laura Belotti, Hospital Sanitary Laboratory, University Hospital of Strasbourg, Strasbourg, France. Appendix A. Supplementary data Supplementary data (video) associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.main.2013.12.003. References [1] Erel E, Aiyenibe B, Butler PE. Microsurgery simulators in virtual reality: review. Microsurgery 2003;23:147–52. [2] Lannon DA, Atkins JA, Butler PE. Non-vital, prosthetic, and virtual reality models of microsurgical training. Microsurgery 2001;21:389–93.
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[3] Meier SA, Lang A, Beer GM. Polyurethane vessels for microvascular surgical training to reduce animal use. ALTEX 2004;21:135–8. [4] Liverneaux PA, Hendriks S, Jesse CS, Sijo J. Parekattil. Robotic Assisted Microsurgery–Development of basic course skill. Arch Plast Surg 2013 [in Press]. [5] Kim DC, Hayward PG, Morrison WA. Training model for microvessel anastomosis. Microsurgery 1994;15:820–1. [6] Mantovani G, Fukushima WY, Baik Cho A, Aita MA, Mazzetti MV. Use of earthworms for microsurgery training. J Reconstr Microsurg 2009;25: 275–8. [7] Merrell JC, Tien NV, Son NT, An LN, Sellers D, Russell R, et al. Introduction of microsurgery in Vietnam by a charitable organization: a 15-year experience. Plast Reconstr Surg 2007;119:1267–73. [8] Katzen JT, Ruiz-Razura A, Leiva J. Teaching microsurgery in developing countries. Bull Am Coll Surg 1997;82:8–12. [9] Leung CC, Ghanem AM, Tos P, Ionac M, Froschauer S, Myers SR. Towards a global understanding and standardization of education and training in microsurgery. Arch Plast Surg 2013;40:304–11. [10] Moris M, Caskey R, Mitchell M, Sawaya D. Surgical skills training restructured for the 21st century. J Surg Res 2012;177:33–6. [11] Ramachandran S, Ghanem AM, Myers SR. Assessment of microsurgery competency-where are we now? Microsurgery 2013;33:406–15. [12] Balasundaram I, Aggarwal R, Darzi LA. Development of a training curriculum for microsurgery. Br J Oral Maxillofac Surg 2010;48:598–606. [13] Hino A. Training in microsurgery using a chicken wing artery. Neurosurgery 2003;52:1495–8. [14] Olabe J, Olabe J. Microsurgical training on an in vitro chicken wing infusion model. Surg Neurol 2009;72:695–9. [15] Chan WY, Matteucci P, Southern SJ. Validation of microsurgical models in microsurgery training and competence: a review. Microsurgery 2007;27: 494–9.
ScienceDirect www.sciencedirect.com Chirurgie de la main 33 (2014) 106–111
Original article
Use of the Konnyaku Shirataki noodle as a low fidelity simulation training model for microvascular surgery in the operating theatre Utilisation des nouilles « konnyaku shirataki » comme modèle d’entraînement de faible fidélité à la microchirurgie vasculaire en salle d’opération G.J.-C. Prunières a, C. Taleb a, S. Hendriks a, H. Miyamoto b, N. Kuroshima c, P.A. Liverneaux a,*, S. Facca a a
Department of hand surgery, Strasbourg university hospital, 10, avenue Baumann, 67403 Illkirch, France b Department of orthopaedics surgery, Graduate school of medicine, university of Tokyo, Tokyo, Japan c Department of orthopaedics, Teikyo university school of medicine, Tokyo, Japan Received 7 September 2013; received in revised form 1 December 2013; accepted 9 December 2013 Available online 4 February 2014
Abstract The aim of this study was to test the feasibility of a type of Japanese noodle, named ‘‘shirataki konnyaku’’, for microsurgery training in the operating room. Thirteen surgical residents without experience in microsurgery had to perform two microsurgical anastomoses: one on a model of a femoral artery of a rat (control) and one on a model of a konnyaku shirataki. Two quantitative variables (time in minutes and number of stitches to perform the anastomosis) and two qualitative variables (patency and tightness of the anastomosis) were measured. Sixty anastomoses were performed with the control model and 62 anastomoses with the konnyaku model. The time of the anatomosis was significantly higher in the control group. The number of stitches was similar in both groups. The patency of the anastomosis was significantly lower in the control group. The tightness (no leak) of the anastomosis was significantly higher in the control group. The ‘‘konnyaku shirataki’’ model could improve the teaching of microsurgery due to its availability, low cost and structural similarity to the animal model. # 2014 Elsevier Masson SAS. All rights reserved. Keywords: Microsurgery; Konnyaku shirataki; Training; Model; Rat
Résumé Le but de ce travail était de tester la faisabilité d’un modèle de nouilles japonaises « konnyaku shirataki » pour l’entraînement en microchirurgie au bloc opératoire. Treize internes en chirurgie sans expérience de microchirurgie devaient réaliser des couples d’anastomoses microchirurgicales avec un modèle d’artère fémorale de rat (témoin) et un modèle de konnyaku shirataki. Deux variables quantitatives (temps en minutes et nombre de points pour réaliser l’anastomose) et deux variables qualitatives (perméabilité et étanchéité de l’anastomose) étaient mesurées. Soixante anastomoses ont été réalisées avec le modèle témoin et 62 anastomoses avec le modèle konnyaku. Le temps d’anastomose était significativement supérieur dans le groupe témoin. Le nombre de points était identique dans les 2 groupes. La perméabilité des anastomoses était significativement inférieure dans le groupe témoin. L’étanchéité des anastomoses était significativement supérieure dans le groupe témoin. Le modèle konnyaku shirataki, par sa disponibilité, son faible coût et sa structure proche du modèle animal pourrait améliorer l’enseignement de la microchirurgie. # 2014 Elsevier Masson SAS. Tous droits réservés. Mots clés : Microchirurgie ; Konnyaku shirataki ; Entraînement ; Modèle ; Rat
* Corresponding author. E-mail address: [email protected] (P.A. Liverneaux). 1297-3203/$ – see front matter # 2014 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.main.2013.12.003
G.-C. Prunières et al. / Chirurgie de la main 33 (2014) 106–111
107
1. Introduction
2. Material and methods
Microsurgery is a cross technique used in many specialties such as plastic surgery, hand surgery, peripheral nerve surgery, ophthalmology or neurosurgery. Practical microsurgery training must be conducted in a laboratory observing international standards as it involves experimentation on animals. It requires a lot of training on virtual [1], synthetic [2,3] or biological experimental models [4,5]. These conventional models have several disadvantages: high cost, complex logistics, and low representation [6]. So far, none of these models has replaced the reference model: the rat. Some developing countries do not have laboratories with international standards. Thus, the training of young surgeons in microsurgery is done mostly overseas, in expensive workshops of short duration [7]. Back in their country of origin, these young microsurgeons encounter difficulties, not only to improve their skills, but also to continue their training [8]. To address this problem, the ideal microsurgery model should meet the following criteria: economical, readily available, and consistent with the sterile environment of the operating room and close to the anatomy of the anastomosed vessels in human microsurgery [5]. The aims of this study were:
This work was done in an accredited animal testing laboratory. The animals were acclimated for at least 2 weeks before the experiments. All procedures were approved by the local Ethics Committee and complied with the legislation on animal experimentation (Directive 2010/63/EU of the European Parliament and the Council of 22 September 2010 on the protection of animals used for scientific purposes). Thirteen surgical residents, preparing for a university degree in microsurgery, were recruited to participate in this work. Each resident was supposed to perform at least one pair of microsurgical anastomoses, one on a rat’s femoral artery model, and the second one on a konnyaku shirataki noodle model. The rat’s femoral artery model required the use of 38 adult male rats of Wistar strain with an average weight of 350 g to achieve 60 anastomoses. The rats were anesthetized by intraperitoneal injection of a solution of 1 mL/100 g ketamine and Midazolam with a maintenance dose of 1 mL every hour. The rats were put in the supine position, both inguinal regions were prepared and addressed surgically. The femoral artery was isolated on a vascular clamp (Biover1, TM Arex, Palaiseau, France), and sectioned, using microsurgical scissors. The konnyaku shirataki model required the use of 104 full noodles of 1.5 mm diameter and 20 mm length to achieve 62 anastomoses. One box contains a dozen konnyaku shirataki noodles approximately 20 cm long, for a total price of about $ 2. Each konnyaku shirataki noodle was drilled (Fig. 1) using a catheter of 0.7 mm diameter (Surflo-W1, TM Terumo Europe,
to test the feasibility of a Japanese noodle of type konnyaku shirataki by comparing the results from a series of konnyaku anastomoses to those of a rat’s femoral artery; to introduce konnyaku shirataki as a microvascular surgical training model in the operating theatre for hospitals with no microsurgical training lab facilities.
Fig. 1. Preparation of a konnyaku shirataki model. Drilling of the model to produce the lumen (A). The catheter needle in place, the konnyaku is incompletely removed to leave a length of 5 mm of lumen to allow anastomosis (B). Model ready to be anastomosed (C).
108
G.-C. Prunières et al. / Chirurgie de la main 33 (2014) 106–111
Fig. 2. Anastomosis of a konnyaku Shirataki model. Penetration of a 10/0 nylon suture needle through the lumen (A). Tightening of the nylon 10/0 (B). Anastomosis completed (C).
Leuven, Belgium). Two konnyaku shirataki noodles were put next to each other, a few millimeters apart, to form an anastomosis model (Fig. 2 and Supplementary data, video). The anastomosis method was the same for both models. An end-to-end anastomosis was performed under a microscope (Wild1, TM Leica Microsystems, Heerbrugg, Switzerland) using 10/0 nylon stitches. The evaluation of the results was the same for both models. Two quantitative variables were measured: the time in minutes and the number of stitches used to perform the anastomosis. Two qualitative variables were evaluated: the patency and absence of anastomotic leak (watertightness) [9–11]. In the control model, patency and leak were evaluated by a conventional auto-fill test after emptying the distal segment of the anastomosed artery. After evaluation, the rats were killed by a lethal dose of ketamine. In the konnyaku shirataki model, patency and number of leaks were evaluated by filling the distal anastomosed segment of the konnyaku shirataki noodle with an injection of a colored product (chlorhexidine alcohol colored 0.5%, Gilbert TM, Herouville Saint Clair, France) through the proximal catheter. The statistical analysis of the four variables was carried out under the Bayesian paradigm. Time is a quantitative, continuous, Gaussian-character variable; the mixed linear regression model was chosen. Considering that the number of stitches is a positive quantitative discrete variable, the mixed regression model of Poisson was chosen. Patency and anastomosis leak being two binary variables, the Joint Logistic regression model was chosen. The significance of the results was assessed using the credible interval 95% of the mean difference in each group. Two averages could be considered
significantly different if the credibility interval of the difference did not contain the value 0. A dietary, bacteriological and fungal analysis was made through the process of maceration in a sterile bag on the konnyaku shirataki themselves (research microorganisms at 30 8C, coagulase-positive Staphylococcus, E. coli, Salmonella, Listeria monocytogenes, Moulds/yeast, Clostridium perfringens, Bacillus cereus) and on their conservation fluid (global analysis by seeding in 1 mL liquid surface on blood agar, incubated at 37 8C for 48 hours, identification of all microorganisms by mass spectrometry). The analyses were performed on day (D) 0 (day the pack was opened), on D7 and on D14. The konnyaku shirataki noodles were transferred into a biological safety cabinet with laminar air flow in a closed sterile container; one part of the noodles were kept at room temperature and another part stored in a refrigerator (5 8C 3 8C).
3. Results The results are reported in Table 1. A total of 60 anastomoses were performed using the femoral artery of the rat and 62 anastomoses using the konnyaku shirataki model. Between them, 54 pairs of microsurgical anastomoses were performed. In 6 cases, only the anastomosis of the rat femoral artery model was performed. In 8 cases, only the anastomosis with the konnyaku shirataki model was performed. Incomplete pairs of anastomoses were due to an insufficient number of shirataki konnyaku models available in some cases, and to the premature death of the rat in other cases.
G.-C. Prunières et al. / Chirurgie de la main 33 (2014) 106–111
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Table 1 Results of a series of 60 anastomoses performed on a rat femoral artery model and 62 anastomoses on a konnyaku shirataki model. Anastomoses (n)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
Rat femoral artery model
Konnyaku shirataki model
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
46 50 60 38 27 180 180 40 26 30 50 50 90 60 50 60 30 25 30 50 45 50 60 60 60 60 30 40 25 40 90 30 30 * 20 60 * 60 30 28 38 90 90 * 120 120 * 20 45 30 20 * * * * 60 45 50 60 60 40 60
4 5 5 5 5 6 4 4 4 6 6 6 5 4 6 6 6 4 5 7 5 5 5 5 6 4 6 9 6 4 4 4 4 * 8 4 * 6 5 6 5 5 6 * 10 7 * 5 6 6 6 * * * * 5 6 7 7 5 5 5
Y N Y N Y Y N N Y Y Y Y N Y Y Y Y Y Y N Y Y N N Y N N Y Y N Y Y Y * Y N * Y Y Y N Y Y * Y Y * Y Y Y Y * * * * Y Y Y Y Y Y N
Y Y N Y Y Y N N Y Y Y Y N N Y N Y Y Y N Y N Y N Y Y Y Y Y Y Y Y Y * Y N * Y Y N Y Y N * Y Y * Y Y Y Y * * * * Y Y Y N N Y N
30 38 30 35 36 20 50 33 43 40 40 20 34 16 10 15 20 15 35 40 15 20 60 30 60 30 25 20 15 15 * * 21 16 20 45 45 25 * 25 30 25 20 25 20 25 25 20 30 20 12 10 15 19 20 20 15 20 25 20 * 20
6 6 3 6 6 6 3 6 6 5 5 5 6 6 6 6 4 6 5 6 4 5 5 5 6 4 7 6 5 7 * * 7 6 7 5 4 5 * 6 5 6 5 6 5 7 6 4 6 6 4 4 5 6 6 5 6 8 6 5 * 6
N N N N Y N N N Y N Y N Y Y Y Y Y Y Y N Y Y N N N N Y Y N Y * * Y Y Y N N N * Y Y Y Y Y N Y Y N Y Y Y Y Y Y Y N Y N N N * Y
Y Y N Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y N Y Y Y Y Y Y Y Y Y Y * * Y Y Y Y Y Y * Y Y Y Y Y N Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y * Y
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110 Table 1 (Continued ) Anastomoses (n)
63 64 65 66 67 68
Rat femoral artery model
Konnyaku shirataki model
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
Time (min)
Stitches (n)
No leak Y/N
Patency Y/N
25 35 80 80 60 60
6 7 5 5 5 6
Y Y Y Y Y Y
Y Y N N Y Y
17 14 20 15 * *
7 7 5 5 * *
Y N Y N * *
Y Y Y Y * *
Y: yes. N: no. *: missing data.
The average time to perform the anastomosis in the rat femoral artery group was 54.6 minutes ( 32.5 min) versus 25.6 minutes ( 11.3 min) in the konnyaku shirataki group. The difference between the two averages was significantly non-zero, according to the parameters estimated by the mixed linear regression model, and after a Box-Cox transformation parameter of –0.27, the difference was 0.2672 [0.2121, 0, 3223]. The average number of stitches to perform the anastomosis in the rat femoral artery group was 5.48 ( 1.21) versus 5.53 ( 1.00) in the konnyaku shirataki group. The difference was not significantly different from 0, according to the mixed Poisson regression model, the difference was –0.0073 [–0.1628, 0.1471]. The patency of the anastomoses in the rat femoral artery group was positive in 69% (37/54) versus 94% (51/54) in the konnyaku shirataki group. The difference was significantly non-zero, according to the Joint Logistic regression model, the difference was 2401 [–4.040, –1.087]. The water-tightness of anastomoses in the control group was 74% (40/54) against 54% (29/54) in the konnyaku shirataki group. The difference was significantly non-zero, according to the Joint Logistic regression model, the difference was –1.463 [–2.530, –0.4855]. 4. Discussion None of the experimental models used for training in microsurgery, whether organic or not, is entirely satisfactory for regular training of surgeons who have no access to laboratory animal facilities [12]. Non-biological polyurethane models have the advantage that they can be sterilized and used in an operating room or laboratory animal facility. However, their mechanical and rheological properties are too far from those of a human or animal artery and thus cannot be considered as validation models [3]. They are used as models for introduction to microsurgery. Non-living biological models, such as chicken thigh arteries [13,14] – or more recently the worm – [6] are anatomically and physiologically more similar to human vessels. However, for regulatory reasons, they can be introduced neither in the operating room nor a laboratory animal facility. These classic models should be removed from the arsenal of training models in microsurgery. In living biological models (mainly rats) [15] delayed testing of the success of vascular anastomoses is possible. However, they
require complex and expensive logistics, which are subject to strict regulations. Many teams do not have access to a laboratory animal facility. This was the main motivation for our work. The ideal microsurgical training model for surgeons, who do not have access to animal experimentation models, must meet the following criteria: availability, cost-effectiveness, standardization, reproducing the properties of the vascular wall, and sterility. The konnyaku shirataki noodle meets these criteria. It is available in food retail at $ 2 for a 228 g-pack, good for at least 100 anastomoses. The konnyaku shirataki noodle has a constant diameter of about 1.5 mm, which corresponds to the femoral artery of a rat. Statistical analysis of the four variables was carried out under the Bayesian paradigm, thus overcoming the limits of decisions set beforehand in frequentist methods. The Bayesian paradigm is used to evaluate the probability of the hypothesis to prove, and thus refine the findings. Moreover, the use of mixed models allows comparing a couple of values in each session, or repeated measures, which significantly reduces bias in the estimates. Results comparing our two models show that the konnyaku shirataki anastomosis is very close to the anastomosis of a rat’s femoral artery. The anastomosis is faster with the konnyaku shirataki model. This can be explained by the absence of adventitia and spasm that keeps the lumen permanently open. The number of stitches required to achieve an anastomosis is identical for both models. Patency was better with the konnyaku shirataki model. This can be explained by the absence of platelet thrombi induced by any damage to the inner luminal wall. However, the watertightness was slightly worse with the konnyaku shirataki model. This can be explained by the absence of platelet plug formation. The results of bacteriological and fungal analysis show that the commercial presentation of the konnyaku shirataki is sterile at D0, D7 and D14. The Committee against nosocomial infections in our institution even allowed its introduction to the operating room. However, we recommend not keeping the konnyaku shirataki in the operating room once the package has been opened twice. 5. Conclusion The konnyaku shirataki model can be introduced in the operating room to perfect the training of junior microsurgeons who do not have access to a proper microsurgery laboratory. It also reduces the number of animals used for training purposes, but does not fully replace the reference model: the rat.
G.-C. Prunières et al. / Chirurgie de la main 33 (2014) 106–111
Disclosure of interest Philippe Liverneaux has conflict of interest with Newclip Technics, Integra, Argomedical, SBI. The other authors declare that they have no conflicts of interest concerning this article. Acknowledgements Mr. Michael Schaeffer, engineer in Biostatistics, Department of Methodology and Biostatistics, University of Strasbourg, Strasbourg, France. Dr. Celine Hernandez and Dr. Laura Belotti, Hospital Sanitary Laboratory, University Hospital of Strasbourg, Strasbourg, France. Appendix A. Supplementary data Supplementary data (video) associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.main.2013.12.003. References [1] Erel E, Aiyenibe B, Butler PE. Microsurgery simulators in virtual reality: review. Microsurgery 2003;23:147–52. [2] Lannon DA, Atkins JA, Butler PE. Non-vital, prosthetic, and virtual reality models of microsurgical training. Microsurgery 2001;21:389–93.
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