RF101 - From Tissue Characterization to In Silico Modeling: Toward a Bioinspired Artificial Ostomy Sphincter for Ostomy Patients

Abstract Podium Presenter(s)

• 

  fabrizio vittadello, Expertise in minivasive colorectal surgery (he/him/his)

  Senior consultant
  Azienda Ospedale Universita Padova
  Azienda Ospedale Università Padova
  Padova, Veneto, Italy

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose

Author(s)

• CF

  Chiara Giulia Fontanella, n/a

  Associate Professor
  Department of Industrial Engineering, University of Padova
  Padova, Veneto, Italy

  Disclosure information not submitted.
• VM

  Veronica Macchi, n/a

  Full Professor of Human Anatomy
  Section of Human Anatomy, Department of Neuroscience, University of Padova
  Padova, Veneto, Italy

  Disclosure information not submitted.
• ES

  Elena Stocco, n/a

  Assistant Professor (RTdB)
  Section of Human Anatomy, Department of Neuroscience
  Padova, Veneto, Italy

  Disclosure information not submitted.
• AR

  Antonio Rella, n/a

  Consultant in General Surgery
  OSA General Surgery - Padua University Hospital
  Padova, Veneto, Italy

  Disclosure information not submitted.
• AG

  Andrea Grego, n/a

  Surgeon in Sant’Antony Hospital Padova
  Escp; Siccr;
  Padova, Veneto, Italy

  Disclosure information not submitted.
• It

  Ilaria toniolo, n/a

  Assistant Professor
  Industrial Engineering Department of University of Padova
  Padova, Veneto, Italy

  Disclosure information not submitted.
• MM

  Maria Vittoria Mascolini, PhD in Industrial Engineering

  Post-doc researcher
  University of Padova
  Padova, Veneto, Italy

  Disclosure information not submitted.
• EC

  Emanuele Luigi Carniel, Ph.D.

  Associate Professor
  University of Padova
  Padova, Veneto, Italy

  Disclosure information not submitted.
• AP

  Alice Pecorino, n/a

  Medical doctor
  University of Padua
  Padova, Veneto, Italy

  Disclosure information not submitted.
• DS

  Daniele Sandonà, n/a

  General Surgery Resident
  OSA General Surgery, Padua University Hospital, 35128 Padua, Italy
  Padova, Veneto, Italy

  Disclosure information not submitted.
• VB

  Veronica Bosco, n/a

  PhD student
  Department of industrial engineering, University of Padova
  Padova, Veneto, Italy

  Disclosure information not submitted.
• 

  Nicola Passuello, MD (he/him/his)

  Senior Consultant in General Surgery
  OSA General Surgery - Padua University Hospital
  Padua University
  PADOVA, Veneto, Italy

  Disclosure information not submitted.

Senior Author(s)

• GS

  Giacomo Sarzo, n/a

  OSA General Surgery Chief Physician
  OSA General Surgery, Padua University Hospital, 35128 Padua, Italy
  Padova, Veneto, Italy

  Disclosure information not submitted.

Purpose/Background: Colostomy is an important treatment for colorectal diseases, but it can significantly impact patients' quality of life with both physical and psychological burdens for patients. Emerging biomedical technologies, such as the development of an Artificial Ostomy Sphincter (AOS), could help restore temporary continence and autonomy, reducing the dependence on external appliances. To design an effective and bioinspired AOS, it is fundamental to create in silico tools capable of accurately simulating the mechanical behavior of the bowel. A detailed understanding of the bowel's structure, composition, and mechanical behavior is essential to develop and validate computational models for tissue-device interaction.

Methods/Interventions: Colon samples were collected from 21 patients undergoing surgery for benign diseases (13F, 8M; 63 ± 11 years; BMI 23.6 ± 3.5 kg/m², ethics code AOP3212). Histomorphometric evaluation was performed on Azan-Mallory-stained sections. Digital images were analyzed using ImageJ software to quantify the thickness of individual wall layers (mucosa, muscularis mucosae, submucosa, circular and longitudinal muscle layers). Collagen content was semi-quantitatively assessed by calculating the percentage of tissue area occupied by collagen (stained blue) relative to the total image area. Mechanical testing (tensile, compression, stress relaxation) was performed along radial, circumferential, and longitudinal directions, with and without Taenia Coli, at strain rates of 1-100%/s using a Biomomentum Mach-1 v500csst.

Results/Outcomes: In accordance with the morphometric study, the mean thicknesses of different tissue layers of the colon were: 669.7 ± 331.5 μm, mucosa; 18.5 ± 8.5 μm, muscularis mucosae; 1173.1 ± 705.7 μm, submucosa; 1813.5 ± 433.4 μm, circular muscle layer; and 1209.2 ± 617.8 μm, longitudinal muscle layer. In parallel, collagen content in the submucosa was evaluated using semi-quantitative analysis of Azan-Mallory-stained sections via ImageJ software. Collagen quantification was expressed as the percentage of image area occupied by collagen relative to the total image area (% = collagen area / total area × 100), yielding an average of 51.16% ± 7.91.

The large bowel demonstrated anisotropic, nonlinear, and viscoelastic properties. Longitudinal samples exhibited higher tensile elastic modulus and ultimate tensile strength, while circumferential ones showed greater strain at failure. Compression elastic modulus and peak stress increased with strain rate. Taenia Coli significantly influenced tissue mechanics. Stress-relaxation tests revealed time-dependent behavior and lower equilibrium stiffness under compression.

Conclusion/Discussion: The combination of histomorphometric findings with mechanical evidence clarifies how tissue organization (layers thickness) and collagen distribution influence the anisotropy and viscoelasticity of the bowel. These insights support the development of in silico tools for modeling the human bowel using the Finite Element Method. This approach aims to connect engineering with clinical innovation, ultimately helping to design implants and improve the quality of life for patients with ostomies.

Figure 1
Samples collection and preparation. Histomorphometric analysis and mechanical testing.
Figure 2
Human large bowel wall 1.25x and Layers' thickness (a-b), tensile tests along Longitudinal and Circumferential directions (c-d). Model of human bowel interacting with an AOS (e).