Master’s degree thesis
Title: Optimization of the T-REMEDIE for tendon repair
The experimental thesis project focused on the reassessment and optimization of the T-rem3die, an innovative implantable device for tendon repair, applicable both in human medicine and veterinary fields. The first phase involved an in-depth analysis of polymeric materials available on the market to identify the one best suited to the specific requirements, followed by the search for a resin highly compatible with the mechanical properties of the selected material. The second phase aimed to refine the device’s geometry using CAD-3D design software, subsequently fabricating the model through 3D printing. Tensile tests were conducted to evaluate the behavior of the tendon with the device inserted and to assess its mechanical properties. Finally, finite element analysis was performed using Ansys software to avoid the costs and time associated with producing physical prototypes. The results obtained were then compared with those from the experimental tests, showing a consistent correlation between the two.
Title: Constitutive modelling of the mechanical behaviour of animal tissue tendons
The purpose of this research is to develop a model of tendons. These are defined as the “soft tissue” of the human body, and the study aims to analyze the contribution of the two main components, matrix and fibers, which determine their behavior in response to stress. The analysis begins with the extraction of test samples from pig legs, whose tendons have a structure and behavior similar to those of humans. The process continues with the measurement of the samples, followed by stress tests using a tensile machine, which allows for the collection of stress, strain, and time data (all while keeping the tendons moist with saline solution to prevent the degradation of their properties due to in vitro conditions). Once the data is collected, it is processed and used to obtain the parameters of the constitutive model through genetic algorithm fitting. The experimentally and numerically obtained curves are then compared to assess the effectiveness of the mathematical model, which is based on the theory of viscoelasticity: although the behavior of tendons (like other soft tissues) closely follows this model, at higher strains, a deviation from the theoretical behavior is observed due to the nonlinear behavior typical of biological tissues.
Master’s degree thesis
Title: Design of the device for repair of T-SURE abdominal hernia. From CAD design to production through techniques prototyping: stereolithography and injection moulding
Abdominal hernia is a pathological condition in which part of an internal organ protrudes through a weakness or opening in the abdominal wall. This typically occurs at anatomical weak points in the abdomen, leading to symptoms such as pain, swelling, and in some cases, bowel obstruction.
The healthcare costs associated with hernia treatment are substantial, and current repair techniques often fail to provide a lasting solution. Long-term outcomes show recurrence rates of up to 40% within ten years, accompanied by postoperative complications such as seroma, infections, and chronic pain.
This thesis aims to develop the T-Sure (Tissue SUrgical REpair), a novel technique for abdominal hernia repair designed to replace traditional sutures. The device is intended to support mesh repair outside the peritoneum, improving the strength of the repair system by joining and securing the edges of the hernia defect. The study focused on the realization of prototypes in 3d printing (stereolithography) through an iterative ’trial and error’ process, followed by insertion tests on bovine intercostal tissue and tensile tests on the tissue-device complex. These tests were aimed at assessing the device’s design and performance in terms of tissue
penetration and insertion. Moreover, it was crucial to ensure that the mechanical properties of the device were compatible with those of the tissue to effectively respond to the stresses on the abdominal wall.
Title: Constitutive modelling of the mechanical behaviour of the bovine abdominal muscle
The goal of this research is to create a Matlab model that can predict the mechanical behavior of a muscle tissue. The work stems from the need to understand the muscular response when it is subjected to stress; knowing the mechanical limits of muscle tissue is essential for designing devices that will then come into contact with it, such as abdominal hernia repair devices, avoiding any damage to the abdominal muscle. Specimens of bovine abdominal tissue were tested uniaxially and with different velocities in order to derive the characteristic mechanical parameters and stress-strain curves. These data, which are results of the same order of magnitude as the human abdominal muscle, will be used to train a GA algorithm so that it is reliable in predicting tissue behavior, thus eliminating physical experiments with animal tissue.
Title: Design and development of an applicator for the insertion of the T-SURE device
The aim of this research focuses on the design and development of an applicator for insertion of a device used as suture in abdominal repair of patients with hernia. The device was designed with SolidWorks software and later produced by 3D printing using resins. After developing several versions and selecting the best in terms of functionality and reliability, this version was subjected to experimental tests on animal tissues, carried out with the support of a surgeon, to evaluate its effectiveness.