Case Report

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J Innov Med Technol 2023; 1(1): 38-43

Published online November 30, 2023

https://doi.org/10.61940/jimt.230006

© Korean Innovative Medical Technology Society

Development of 3D printed snap-fit connection for a magnetic anal sphincter

Moon Gu Lee1 , Hyung Jin Kim2

1Department of Mechanical Engineering, College of Engineering, Ajou University, Suwon, Korea, 2Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea

Correspondence to : Moon Gu Lee
Department of Mechanical Engineering, College of Engineering, Ajou University, 206 Wordcup-ro, Yeongtong-gu, Suwon 16499, Korea
e-mail moongulee@ajou.ac.kr
https://orcid.org/0000-0002-1607-806X

Received: November 11, 2023; Revised: November 14, 2023; Accepted: November 14, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

In this paper, we propose a connection that replaces the conventional surgical knotting to improve the ease of procedure, to reduce surgical time, and to secure the connection of a magnetic anal sphincter. The magnetic anal sphincter is implanting device to prevent fecal incontinence of patients. The proposed connection has a kind of simple snap-fit made by 3D printing. This mechanism may help skilled surgeons reduce the time required to knot the magnetic sphincter device when he/she is implanting it on a patient. In addition, the 3D printed snap-fit connection allows even novices to perform the procedure easily and the connection is secure.

Keywords Snap-fit kont; Magnetic anal sphincter; Fecal incontinence

Fecal incontinence is a disease in which feces in the rectum suddenly leaks out of the anus due to lack of control bowel movements. It generally occurs in older people or people in nursing homes or shelters1. Because the leak is without warning, the fecal incontinence has a significant negative impact on the quality of patients’ life. It causes mental distress to the patients and adverse effect on their social life.

When a large area of the anal sphincter is destroyed and then fecal incontinence occurs, standard sphincter repair surgery or anoplasty are performed2. If these attempts fail, a medical device that reinforces the sphincter can be implanted into the anus through a transplanting procedure. Artificial bowel sphincters have been used for this purpose, but recently, a magnetic anal sphincter was introduced as a less invasive method as shown in Fig. 13-5.

Figure 1.FENIX® Continence Restoration System (Torax Medical Inc., St. Paul, MN, USA). (A) Working principle. (B) Closed position with a knot.

This device still has room for improvement. The final step in the above-mentioned fecal incontinence prevention surgery is to secure the device around the upper anal canal by tying the knot connected to both ends’ suture line of the device together. The incised wound is then closed with absorbable sutures to prevent drainage6. Although it is known to be less invasive and have a better prognosis than surgery using the conventional artificial bowel sphincters, the surgery is still inconvenient and time-consuming for colorectal surgeons due to the multiple suturing processes.

Among the multiple sutures, what this study focused on is the final knotting process that connects the two ends’ suture line of the device. This knot should be easy to tie but secure the device firmly. For the procedure using the Lehur’s conventional device, however, the colorectal surgeon directly knots the suture line ends attached to the eyelets. This is a difficult or time-consuming for novices, and there is a risk that it will come loose even if they are tied well.

To make this final knotting step easier and faster, this study proposes using a snap-fit mechanism instead of the knot. In Fig. 1B, the yellow arrows indicate the colorectal surgeon’s knot, which ties the sutures attached to the eyelets at each end of the sphincter device. In contrast, Fig. 2 shows the device just before connecting with a proposed snap-fit instead of the knot. To prevent tissue surrounding the anal canal from penetrating into this area, this junction is covered with a cap (20 mm in diameter).

Figure 2.Magnetic anal sphincter with proposed snap-fit knotting.

Before joining, the two main parts of this connection look like Fig. 3. The snap has four elastic cantilevers (18 mm long), each of which has a wedge-shaped tip. There is a step from this tip to the cantilever. To connect, the snap is pushed into the fit, which connects as shown in Fig. 4. At this time, the cantilever is elastically deformed, and the snap is combined with the fit to maintain the connection7. These connection forms a firm fastening that is not reversed. If the colorectal surgeon wants the remove the device, the wire in Fig. 2 should be cut during the following reoperation.

Figure 3.Proposed cantilever snap-fit.

Figure 4.Cantilever’s behavior during connection.

To make sure, we firstly fabricate several designs with 3D printing. The result is shown in Fig. 5. It was manufactured using Objet30 Pro 3D printer (Strasys Ltd., Eden Prairie, MN, USA). Its material is acrylate-based plastic. Among the various designs, we tried to make the snap-fit small but enough to fit together well and not to be broken. In particular, the cantilever length was carefully determined, and the wedge surface was also created with a smooth curve. This design was then utilized to make a metal snap-fit from stainless steel (SUS 316L) using a metal 3D printing process. A new magnetic anal sphincter with the snap-fit, magnets coated with silicone, and an elastic rubber band wire, was fabricated as shown in Fig. 6. Stainless steel, silicone coating, and rubber bands were selected for biocompatibility.

Figure 5.Snap and fit for connection. (A) Snap with 4 cantilever & wedges. (B) Fit with hollow inner space. L: cantilever length.

Figure 6.Fabricated magnetic anal sphincter with biocompatible metallic snap-fit. (A) Snap-fit made of SUS 316L. (B) Magnetic anal sphincter with the proposed connection.

To check whether the magnetic anal sphincter with the proposed connection worked well, a phantom mimicking a rectum and anus was devised as shown in Fig. 7A. This phantom has a vertical pipe, like a rectum, and a flexible tube that mimics the anal canal. Water corresponding to feces is supplied into the pipe then inner pressure is developed. Meanwhile, some water branch out of the pipe goes to the pressure sensor, which measures the pressure inside the canal.

Figure 7.Experimental phantom and anal sphincter’s squeeze pressure. (A) Closed state when P<2 kPa. (B) Open state when P>2 kPa. P: pipe-rectum, tube–anus canal, water–feces.

According to reports in the literature, the maximum pressure exerted when a patient pushes stool out of the rectum is approximately 3–40 kPa (20–300 mmHg)8. Assuming that defecation begins when a pressure of 2–3 kPa is applied to a patient’s sphincter, we checked whether the magnetic anal sphincter with the connection opens well at the pressure range and discharges water corresponding to feces. As a result, it was confirmed that defecation occurred properly as shown in Fig. 7B.

It is anticipated that the connection time will be reduced by using the proposed snap-fit compared to the time required to connect the conventional sphincter device. In the conventional device, a knot is needed to connect both ends. According to discussion with a colorectal surgeon, it takes about 10–30 seconds to tie one knot. Assuming that he/she ties two knots to securely tie the sutures at both ends, it is expected to take 20–60 seconds. If the proposed snap fit method is used, this time will take approximately 13 seconds, and it is expected to take less time since the connection is completed with a single push.

During more than 100 experiments on the phantom, the metal snap-fit has never separated. Typically, surgical knots should be tied more than twice to ensure adequate tension and prevent from coming undone9. Therefore, it can be said that the connection method proposed here is safe and guarantees a certain degree of tension.

This magnetic anal sphincter uses a magnet. Since the magnet is made of heavy metals such as neodymium or samarium, which are harmful to the human body, biocompatibility may be problematic if it is not properly coated. Additionally, even with coated magnets, there is a risk of inflammation and necrosis if tissue gets caught between the magnets in the closed position. It seems a good idea to wrap the outside of the magnetic anal sphincter with a donut-shaped silicone tube to prevent tissue pinching.

Since the snap-fit type connection is a permanent connection, it has the disadvantage of not being able to be removed and corrected during the surgical procedure. Therefore, the appropriate position and length must be secured during the surgical process and then the snap-fit connection must be completed at the end. If the proper connection is not made, the surgeon must cut the rubber band wire and use another new device. Some snap-fit allow modification, so it is worth trying to apply them to the device.

If the outer surface of the cantilever snap-fit’s wedge is not designed to be smooth and curved, it may not be easy to join or it may be broken. If the length of the cantilever is not appropriate, it may be too difficult to fit or may be too loosely coupled. In this study, the first attempts to fabricate several snap fits were performed with plastic materials because the 3D printing process using metal is very expensive. The metal can be titanium and stainless steel. The former is more expensive, and the latter is cheaper. However, the titanium is recently more widely used in medical implant.

The range of pressure that opens the anus in the phantom used in this study was set to over 2 kPa, but other literature reports that the anus opens at pressures greater than this pressure10. Therefore, it is necessary to find the appropriate pressure, conduct more new experiments, and perform statistical analysis.

The time it takes for a surgeon to tie a surgical knot was estimated to be 10–30 seconds through discussion with the surgeons, but this is not based on appropriate statistics. Therefore, more data on this is required. It was thought that the connection of this device has been robust after more than 100 experiments. However, if the actual patient defecated daily and his expected survival was 5 years, more than 1,800 experiments would be needed. Therefore, this also needs to be analyzed by conducting more experiments and obtaining more data.

In this study, the previously proposed magnetic anal sphincter device was improved to enable easy, fast and robust connection. For this connection, a snap-fit mechanism made of metal was designed and manufactured, and its usefulness was tested on a phantom. As a result, it was possible to develop a magnetic anal sphincter device with a connector that allows for a faster, easier, but more robust connection. The differences between the conventional and proposed connections are listed in Table 1.

Table 1 Differences between the conventional and the proposed connections

Conventional wayProposed way
Connection methodTying square or surgeon’s knotPushing snap into fit in cap
Required instrumentsFinger, needle, and scissorsFingers
AdvantagesFamiliar to surgeonsFast, easy, and robust

However, this study still has risks to the human body, irreversibility of the surgery, high cost of the device, and limitations of the experiment. Therefore, additional animal or human test is necessary.

No potential conflict of interest relevant to this article was reported.

  1. Nelson RL. Epidemiology of fecal incontinence. Gastroenterology 2004;126(1 Suppl 1):S3-S7. https://doi.org/10.1053/j.gastro.2003.10.010.
    Pubmed CrossRef
  2. Christiansen J. Modern surgical treatment of anal incontinence. Ann Med 1998;30:273-277. https://doi.org/10.3109/07853899809005855.
    Pubmed CrossRef
  3. Rao SS. Current and emerging treatment options for fecal incontinence. J Clin Gastroenterol 2014;48:752-764. https://doi.org/10.1097/MCG.0000000000000180.
    Pubmed KoreaMed CrossRef
  4. Madoff RD, Rosen HR, Baeten CG, et al. Safety and efficacy of dynamic muscle plasty for anal incontinence: lessons from a prospective, multicenter trial. Gastroenterology 1999;116:549-556. https://doi.org/10.1016/s0016-5085(99)70176-9.
    Pubmed CrossRef
  5. Lehur PA. The magnetic anal sphincter: an option to treat fecal incontinence. Proceedings of 7th Biennnial congress of ASEAN Society (ASCS), 2014 Jul 16-18; Singapore.
  6. Mantoo S, Meurette G, Podevin J, Lehur PA. The magnetic anal sphincter: a new device in the management of severe fecal incontinence. Expert Rev Med Devices 2012;9:483-490. https://doi.org/10.1586/erd.12.38.
    Pubmed CrossRef
  7. Klahn C, Singer D, Meboldt M. Design guidelines for additive manufactured snap-fit joints. Procedia CIRP 2016;50:264-269. https://doi.org/10.1016/j.procir.2016.04.130.
    CrossRef
  8. Bak YT. Anorectal functional testing. Korean J Neurogastroenterol Motil 1999;5:215-226.
    Pubmed CrossRef
  9. Ching SS, Mok CW, Koh YX, Tan SM, Tan YK. Assessment of surgical trainees' quality of knot-tying. J Surg Educ 2013;70:48-54. https://doi.org/10.1016/j.jsurg.2012.07.002.
    Pubmed CrossRef
  10. Pedersen IK, Christiansen J. A study of the physiological variation in anal manometry. Br J Surg 1989;76:69-70. https://doi.org/10.1002/bjs.1800760121.
    Pubmed CrossRef

Article

Case Report

J Innov Med Technol 2023; 1(1): 38-43

Published online November 30, 2023 https://doi.org/10.61940/jimt.230006

Copyright © Korean Innovative Medical Technology Society.

Development of 3D printed snap-fit connection for a magnetic anal sphincter

Moon Gu Lee1 , Hyung Jin Kim2

1Department of Mechanical Engineering, College of Engineering, Ajou University, Suwon, Korea, 2Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea

Correspondence to:Moon Gu Lee
Department of Mechanical Engineering, College of Engineering, Ajou University, 206 Wordcup-ro, Yeongtong-gu, Suwon 16499, Korea
e-mail moongulee@ajou.ac.kr
https://orcid.org/0000-0002-1607-806X

Received: November 11, 2023; Revised: November 14, 2023; Accepted: November 14, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In this paper, we propose a connection that replaces the conventional surgical knotting to improve the ease of procedure, to reduce surgical time, and to secure the connection of a magnetic anal sphincter. The magnetic anal sphincter is implanting device to prevent fecal incontinence of patients. The proposed connection has a kind of simple snap-fit made by 3D printing. This mechanism may help skilled surgeons reduce the time required to knot the magnetic sphincter device when he/she is implanting it on a patient. In addition, the 3D printed snap-fit connection allows even novices to perform the procedure easily and the connection is secure.

Keywords: Snap-fit kont, Magnetic anal sphincter, Fecal incontinence

Introduction

Fecal incontinence is a disease in which feces in the rectum suddenly leaks out of the anus due to lack of control bowel movements. It generally occurs in older people or people in nursing homes or shelters1. Because the leak is without warning, the fecal incontinence has a significant negative impact on the quality of patients’ life. It causes mental distress to the patients and adverse effect on their social life.

When a large area of the anal sphincter is destroyed and then fecal incontinence occurs, standard sphincter repair surgery or anoplasty are performed2. If these attempts fail, a medical device that reinforces the sphincter can be implanted into the anus through a transplanting procedure. Artificial bowel sphincters have been used for this purpose, but recently, a magnetic anal sphincter was introduced as a less invasive method as shown in Fig. 13-5.

Figure 1. FENIX® Continence Restoration System (Torax Medical Inc., St. Paul, MN, USA). (A) Working principle. (B) Closed position with a knot.

This device still has room for improvement. The final step in the above-mentioned fecal incontinence prevention surgery is to secure the device around the upper anal canal by tying the knot connected to both ends’ suture line of the device together. The incised wound is then closed with absorbable sutures to prevent drainage6. Although it is known to be less invasive and have a better prognosis than surgery using the conventional artificial bowel sphincters, the surgery is still inconvenient and time-consuming for colorectal surgeons due to the multiple suturing processes.

Case Report

Among the multiple sutures, what this study focused on is the final knotting process that connects the two ends’ suture line of the device. This knot should be easy to tie but secure the device firmly. For the procedure using the Lehur’s conventional device, however, the colorectal surgeon directly knots the suture line ends attached to the eyelets. This is a difficult or time-consuming for novices, and there is a risk that it will come loose even if they are tied well.

To make this final knotting step easier and faster, this study proposes using a snap-fit mechanism instead of the knot. In Fig. 1B, the yellow arrows indicate the colorectal surgeon’s knot, which ties the sutures attached to the eyelets at each end of the sphincter device. In contrast, Fig. 2 shows the device just before connecting with a proposed snap-fit instead of the knot. To prevent tissue surrounding the anal canal from penetrating into this area, this junction is covered with a cap (20 mm in diameter).

Figure 2. Magnetic anal sphincter with proposed snap-fit knotting.

Before joining, the two main parts of this connection look like Fig. 3. The snap has four elastic cantilevers (18 mm long), each of which has a wedge-shaped tip. There is a step from this tip to the cantilever. To connect, the snap is pushed into the fit, which connects as shown in Fig. 4. At this time, the cantilever is elastically deformed, and the snap is combined with the fit to maintain the connection7. These connection forms a firm fastening that is not reversed. If the colorectal surgeon wants the remove the device, the wire in Fig. 2 should be cut during the following reoperation.

Figure 3. Proposed cantilever snap-fit.

Figure 4. Cantilever’s behavior during connection.

To make sure, we firstly fabricate several designs with 3D printing. The result is shown in Fig. 5. It was manufactured using Objet30 Pro 3D printer (Strasys Ltd., Eden Prairie, MN, USA). Its material is acrylate-based plastic. Among the various designs, we tried to make the snap-fit small but enough to fit together well and not to be broken. In particular, the cantilever length was carefully determined, and the wedge surface was also created with a smooth curve. This design was then utilized to make a metal snap-fit from stainless steel (SUS 316L) using a metal 3D printing process. A new magnetic anal sphincter with the snap-fit, magnets coated with silicone, and an elastic rubber band wire, was fabricated as shown in Fig. 6. Stainless steel, silicone coating, and rubber bands were selected for biocompatibility.

Figure 5. Snap and fit for connection. (A) Snap with 4 cantilever & wedges. (B) Fit with hollow inner space. L: cantilever length.

Figure 6. Fabricated magnetic anal sphincter with biocompatible metallic snap-fit. (A) Snap-fit made of SUS 316L. (B) Magnetic anal sphincter with the proposed connection.

To check whether the magnetic anal sphincter with the proposed connection worked well, a phantom mimicking a rectum and anus was devised as shown in Fig. 7A. This phantom has a vertical pipe, like a rectum, and a flexible tube that mimics the anal canal. Water corresponding to feces is supplied into the pipe then inner pressure is developed. Meanwhile, some water branch out of the pipe goes to the pressure sensor, which measures the pressure inside the canal.

Figure 7. Experimental phantom and anal sphincter’s squeeze pressure. (A) Closed state when P<2 kPa. (B) Open state when P>2 kPa. P: pipe-rectum, tube–anus canal, water–feces.

According to reports in the literature, the maximum pressure exerted when a patient pushes stool out of the rectum is approximately 3–40 kPa (20–300 mmHg)8. Assuming that defecation begins when a pressure of 2–3 kPa is applied to a patient’s sphincter, we checked whether the magnetic anal sphincter with the connection opens well at the pressure range and discharges water corresponding to feces. As a result, it was confirmed that defecation occurred properly as shown in Fig. 7B.

It is anticipated that the connection time will be reduced by using the proposed snap-fit compared to the time required to connect the conventional sphincter device. In the conventional device, a knot is needed to connect both ends. According to discussion with a colorectal surgeon, it takes about 10–30 seconds to tie one knot. Assuming that he/she ties two knots to securely tie the sutures at both ends, it is expected to take 20–60 seconds. If the proposed snap fit method is used, this time will take approximately 13 seconds, and it is expected to take less time since the connection is completed with a single push.

During more than 100 experiments on the phantom, the metal snap-fit has never separated. Typically, surgical knots should be tied more than twice to ensure adequate tension and prevent from coming undone9. Therefore, it can be said that the connection method proposed here is safe and guarantees a certain degree of tension.

Discussion

This magnetic anal sphincter uses a magnet. Since the magnet is made of heavy metals such as neodymium or samarium, which are harmful to the human body, biocompatibility may be problematic if it is not properly coated. Additionally, even with coated magnets, there is a risk of inflammation and necrosis if tissue gets caught between the magnets in the closed position. It seems a good idea to wrap the outside of the magnetic anal sphincter with a donut-shaped silicone tube to prevent tissue pinching.

Since the snap-fit type connection is a permanent connection, it has the disadvantage of not being able to be removed and corrected during the surgical procedure. Therefore, the appropriate position and length must be secured during the surgical process and then the snap-fit connection must be completed at the end. If the proper connection is not made, the surgeon must cut the rubber band wire and use another new device. Some snap-fit allow modification, so it is worth trying to apply them to the device.

If the outer surface of the cantilever snap-fit’s wedge is not designed to be smooth and curved, it may not be easy to join or it may be broken. If the length of the cantilever is not appropriate, it may be too difficult to fit or may be too loosely coupled. In this study, the first attempts to fabricate several snap fits were performed with plastic materials because the 3D printing process using metal is very expensive. The metal can be titanium and stainless steel. The former is more expensive, and the latter is cheaper. However, the titanium is recently more widely used in medical implant.

The range of pressure that opens the anus in the phantom used in this study was set to over 2 kPa, but other literature reports that the anus opens at pressures greater than this pressure10. Therefore, it is necessary to find the appropriate pressure, conduct more new experiments, and perform statistical analysis.

The time it takes for a surgeon to tie a surgical knot was estimated to be 10–30 seconds through discussion with the surgeons, but this is not based on appropriate statistics. Therefore, more data on this is required. It was thought that the connection of this device has been robust after more than 100 experiments. However, if the actual patient defecated daily and his expected survival was 5 years, more than 1,800 experiments would be needed. Therefore, this also needs to be analyzed by conducting more experiments and obtaining more data.

In this study, the previously proposed magnetic anal sphincter device was improved to enable easy, fast and robust connection. For this connection, a snap-fit mechanism made of metal was designed and manufactured, and its usefulness was tested on a phantom. As a result, it was possible to develop a magnetic anal sphincter device with a connector that allows for a faster, easier, but more robust connection. The differences between the conventional and proposed connections are listed in Table 1.

Table 1 . Differences between the conventional and the proposed connections.

Conventional wayProposed way
Connection methodTying square or surgeon’s knotPushing snap into fit in cap
Required instrumentsFinger, needle, and scissorsFingers
AdvantagesFamiliar to surgeonsFast, easy, and robust


However, this study still has risks to the human body, irreversibility of the surgery, high cost of the device, and limitations of the experiment. Therefore, additional animal or human test is necessary.

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Acknowledgments

None.

Fig 1.

Figure 1.FENIX® Continence Restoration System (Torax Medical Inc., St. Paul, MN, USA). (A) Working principle. (B) Closed position with a knot.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Fig 2.

Figure 2.Magnetic anal sphincter with proposed snap-fit knotting.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Fig 3.

Figure 3.Proposed cantilever snap-fit.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Fig 4.

Figure 4.Cantilever’s behavior during connection.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Fig 5.

Figure 5.Snap and fit for connection. (A) Snap with 4 cantilever & wedges. (B) Fit with hollow inner space. L: cantilever length.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Fig 6.

Figure 6.Fabricated magnetic anal sphincter with biocompatible metallic snap-fit. (A) Snap-fit made of SUS 316L. (B) Magnetic anal sphincter with the proposed connection.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Fig 7.

Figure 7.Experimental phantom and anal sphincter’s squeeze pressure. (A) Closed state when P<2 kPa. (B) Open state when P>2 kPa. P: pipe-rectum, tube–anus canal, water–feces.
Journal of Innovative Medical Technology 2023; 1: 38-43https://doi.org/10.61940/jimt.230006

Table 1 . Differences between the conventional and the proposed connections.

Conventional wayProposed way
Connection methodTying square or surgeon’s knotPushing snap into fit in cap
Required instrumentsFinger, needle, and scissorsFingers
AdvantagesFamiliar to surgeonsFast, easy, and robust

References

  1. Nelson RL. Epidemiology of fecal incontinence. Gastroenterology 2004;126(1 Suppl 1):S3-S7. https://doi.org/10.1053/j.gastro.2003.10.010.
    Pubmed CrossRef
  2. Christiansen J. Modern surgical treatment of anal incontinence. Ann Med 1998;30:273-277. https://doi.org/10.3109/07853899809005855.
    Pubmed CrossRef
  3. Rao SS. Current and emerging treatment options for fecal incontinence. J Clin Gastroenterol 2014;48:752-764. https://doi.org/10.1097/MCG.0000000000000180.
    Pubmed KoreaMed CrossRef
  4. Madoff RD, Rosen HR, Baeten CG, et al. Safety and efficacy of dynamic muscle plasty for anal incontinence: lessons from a prospective, multicenter trial. Gastroenterology 1999;116:549-556. https://doi.org/10.1016/s0016-5085(99)70176-9.
    Pubmed CrossRef
  5. Lehur PA. The magnetic anal sphincter: an option to treat fecal incontinence. Proceedings of 7th Biennnial congress of ASEAN Society (ASCS), 2014 Jul 16-18; Singapore.
  6. Mantoo S, Meurette G, Podevin J, Lehur PA. The magnetic anal sphincter: a new device in the management of severe fecal incontinence. Expert Rev Med Devices 2012;9:483-490. https://doi.org/10.1586/erd.12.38.
    Pubmed CrossRef
  7. Klahn C, Singer D, Meboldt M. Design guidelines for additive manufactured snap-fit joints. Procedia CIRP 2016;50:264-269. https://doi.org/10.1016/j.procir.2016.04.130.
    CrossRef
  8. Bak YT. Anorectal functional testing. Korean J Neurogastroenterol Motil 1999;5:215-226.
    Pubmed CrossRef
  9. Ching SS, Mok CW, Koh YX, Tan SM, Tan YK. Assessment of surgical trainees' quality of knot-tying. J Surg Educ 2013;70:48-54. https://doi.org/10.1016/j.jsurg.2012.07.002.
    Pubmed CrossRef
  10. Pedersen IK, Christiansen J. A study of the physiological variation in anal manometry. Br J Surg 1989;76:69-70. https://doi.org/10.1002/bjs.1800760121.
    Pubmed CrossRef
Journal of Innovative Medical Technology
Nov 30, 2023 Vol.1 No.1, pp. 1~9

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