Hernia is a physiological condition that significantly impacts patients’ quality of life. Surgical treatment for hernias often involves the use of specialized meshes to support the abdominal wall. While this method is highly effective, it frequently leads to complications such as pain, infections, inflammation, adhesions, and even the need for revision surgeries. According to the Food and Drug Administration (FDA), hernia recurrence rates can reach up to 11%, surgical site infections occur in up to 21% of cases, and chronic pain incidence ranges from 0.3% to 68%. These statistics highlight the urgent need to improve mesh technologies to minimize such complications. The design and material composition of meshes are critical in reducing postoperative complications. Moreover, integrating drug-eluting properties into the meshes could address issues like infections and inflammation by enabling localized delivery of antibiotics and anti-inflammatory agents. Mesh design is equally important, with innovative structures like auxetic designs offering enhanced mechanical properties, flexibility, and tissue integration. These advanced designs can distribute stress more evenly, reduce fatigue, and improve performance in areas subjected to high pressures, such as during intense coughing, sneezing, or heavy lifting. Technological advancements, such as 3D printing, enable the precise fabrication of meshes with tailored designs and properties, providing new opportunities for innovation. By addressing these challenges, the development of next-generation mesh implants has the potential to reduce complications, improve patient outcomes, and significantly enhance quality of life for individuals undergoing hernia repair.

Pelvic organ prolapse (POP) occurs due to inadequate support of female pelvic organs and is often treated with synthetic implants. However, complications like infections, mesh shrinkage, and tissue erosion can arise due to biomechanical incompatibilities with native tissue. This study aimed to optimize the melt electrowriting process using medical-grade biodegradable Poly(ε-caprolactone) (PCL) with a pellet extruder to print meshes that mimic the mechanical properties of vaginal tissue. Square and diagonal mesh designs with filament diameters of 80 µm, 160 µm, and 240 µm were produced and evaluated through mechanical testing, comparing them to a commercial mesh and sheep vaginal tissue. The results showed that when comparing medical-grade with non-medical-grade square meshes, there was a 54% difference in the Secant modulus, with the non-medical-grade meshes falling short of matching the properties of vaginal tissue. The square-shaped medical-grade PCL mesh closely approximated vaginal tissue, showing only a 13.7% higher Secant modulus and a maximum stress of 0.29 MPa, indicating strong performance. Although the diagonal-shaped mesh exhibited a 14% stress difference, its larger Secant modulus discrepancy of 45% rendered it less suitable. In contrast, the commercial mesh was significantly stiffer, measuring 77.5% higher than vaginal tissue. The diagonal-shaped mesh may better match the stress–strain characteristics of vaginal tissue, but the square-shaped mesh offers stronger support due to its higher stress–strain curve. Overall, meshes printed with medical-grade PCL show superior performance compared to non-medical-grade meshes, suggesting that they are a promising avenue for future advancements in the field of POP repair.

Additive manufacturing technologies have numerous advantages over conventional technologies; nevertheless, their production process can lead to high residual stresses and distortions in the produced parts. The use of numerical simulation models is presented as a solution to predict the deformations and residual stresses resulting from the printing process. This study aimed to predict the tensions and distortions imposed in the gear repair process by directed energy deposition (DED). First, the case study proposed by National Institute of Standards and Technology (NIST) was analyzed to validate the model and the numerically obtained results. Subsequently, a parametric study of the influence of some of the parameters of DED technology was carried out. The results obtained for the validation of the NIST benchmark bridge model were in agreement with the results obtained experimentally. In turn, the results obtained from the parametric study were almost always in line with what is theoretically expected; however, some results were not very clear and consistent. The results obtained help to clarify the influence of certain printing parameters. The proposed model allowed accounting for the effect of residual stresses in calculating the stresses resulting from gear loading, which are essential data for fatigue analysis. Modeling and simulating a deposition process can be challenging due to several factors, including calibrating the model, managing the computational cost, accounting for boundary conditions, and accurately representing material properties. This paper aimed to carefully address these parameters in two case studies, towards reliable simulations.

Stress urinary incontinence often results from pelvic support structures’ weakening or damage. This dysfunction is related to direct injury of the pelvic organ’s muscular, ligamentous or connective tissue structures due to aging, vaginal delivery or increase of the intra-abdominal pressure, for example, defecation or due to obesity. Mechanical changes alter the soft tissues’ microstructural composition and therefore may affect their biomechanical properties. This study focuses on adapting an inverse finite element analysis to estimate the in vivo bladder’s biomechanical properties of two groups of women (continent group (G1) and incontinent group (G2)). These properties were estimated based on MRI, by comparing measurement of the bladder neck’s displacements during dynamic MRI acquired in Valsalva maneuver with the results from inverse analysis. For G2, the intra-abdominal pressure was adjusted after applying a 95% impairment to the supporting structures. The material parameters were estimated for the two groups using the Ogden hyperelastic constitutive model. Finite element analysis results showed that the bladder tissue of women with stress urinary incontinence have the highest stiffness (α ₁ = 0.202 MPa and µ ₁ = 7.720 MPa) approximately 47% higher when compared to continent women. According to the bladder neck’s supero-inferior displacement measured in the MRI, the intra-abdominal pressure values were adjusted for the G2, presenting a difference of 20% (4.0 kPa for G1 and 5.0 kPa for G2). The knowledge of the pelvic structures’ biomechanical properties, through this non-invasive methodology, can be crucial in the choice of the synthetic mesh to treat dysfunction when considering personalized options.

Pelvic organ prolapse (POP) is a common condition among women, characterized by the descent of pelvic organs through the vaginal canal. Although traditional synthetic meshes are widely utilized, they are associated with complications such as erosion, infection, and tissue rejection. This study explores the design and fabrication of biodegradable auxetic implants using polycaprolactone and melt electrowriting technology, with the goal of developing implants that closely replicate the mechanical behavior of vaginal tissue while minimizing implant-related complications. Four distinct auxetic mesh geometries—re-entrant Evans, Lozenge grid, square grid, and three-star honeycomb—were fabricated with a 160 $\mathrm{\mu }$m diameter and mechanically evaluated through uniaxial tensile testing. The results indicate that the square grid and three-star honeycomb geometries exhibit hyperelastic-like behavior, closely mimicking the stress–strain response of vaginal tissue. The re-entrant Evans geometry has been observed to exhibit excessive stiffness for applications related to POP, primarily due to material overlap. This geometry demonstrates stiffness that is approximately five times greater than that of the square grid or the three-star honeycomb configurations, which contributes to an increase in local rigidity. The unique auxetic properties of these structures prevent the bundling effect observed in synthetic meshes, promoting improved load distribution and minimizing the risk of tissue compression. Additionally, increasing the extrusion diameter has been identified as a promising strategy for further refining the biomechanical properties of these meshes. These findings lay a solid foundation for the development of next-generation biodegradable implants.