This paper presents a finite element analysis to investigate the biomechanical changes caused by transforaminal (TLIF) and anterior lumbar interbody fusion (ALIF) at the L5-S1 level, applying two different implants: T_PAL (TLIF) and SynFix (ALIF). The main objective is to determine which one is more stable for patients. Numerical simulations of segmental motion show that, in the early postoperative phase, displacements and rotation angles obtained in ALIF are greater than the corresponding ones obtained in TLIF, as well as the principal stress values on the ligaments. So, TLIF performed with T_PAL is more stable than ALIF, especially during the recovery phase.

The fetal membranes are an essential mechanical structure for pregnancy, protecting the developing fetus in an amniotic fluid environment and rupturing before birth. In cooperation with the cervix and the uterus, the fetal membranes support the mechanical loads of pregnancy. Structurally, the fetal membranes comprise two main layers: the amnion and the chorion. The mechanical characterization of each layer is crucial to understanding how each layer contributes to the structural performance of the whole membrane. The in-vivo mechanical loading of the fetal membranes and the amount of tissue stress generated in each layer throughout gestation remains poorly understood, as it is difficult to perform direct measurements on pregnant patients. Finite element analysis of pregnancy offers a computational method to explore how anatomical and tissue remodeling factors influence the load-sharing of the uterus, cervix, and fetal membranes. To aid in the formulation of such computational models of pregnancy, this work develops a fiber-based multilayer fetal membrane model that captures its response to previously published bulge inflation loading data. First, material models for the amnion, chorion, and maternal decidua are formulated, informed, and validated by published data. Then, the behavior of the fetal membrane as a layered structure was analyzed, focusing on the respective stress distribution and thickness variation in each layer. The layered computational model captures the overall behavior of the fetal membranes, with the amnion being the mechanically dominant layer. The inclusion of fibers in the amnion material model is an important factor in obtaining reliable fetal membrane behavior according to the experimental dataset. These results highlight the potential of this layered model to be integrated into larger biomechanical models of the gravid uterus and cervix to study the mechanical mechanisms of preterm birth.

This study researches the viscous and hyperelastic mechanical behaviors of hydrogel-based nanocomposite materials, including: (i) a composite of human methacryloyl platelet lysate (hPLMA), human platelet lysates (hPL), and nanohydroxyapatite (nHA); (ii) bovine serum albumin methacryloyl (BSAMA); and (iii) hyaluronic acid methacryloyl (HAMA). These materials stand out for their enhanced bioactivity and mechanical strength compared to traditional hydrogels. Their potential applications in various scaffold architectures and the biomechanical restoration of the mandibular joint are investigated. Mechanical compression and relaxation tests are performed on the hydrogel-based samples, with varying nHA content (0%, 1%, and 5%) in the hPL/hPLMA composite, to characterize their visco-hyperelastic behavior. Mechanical parameters are optimized using a micro-genetic algorithm. Results show that increasing nHA content raises compressive stress and intensifies the viscoelastic response. Besides, higher strut density and staggered orthogonal patterns produce more uniform stress distribution despite a less stable viscous response. In in silico simulations of the human mandible, a multimaterial scaffold was created, featuring a hydrogel core with ceramic-based scaffold ends (hydroxyapatite-based cement enriched with hPL). The ceramic phase provided effective mechanical protection for the hydrogel. Besides, substituting the hPL/hPLMA core with HAMA reduced the stress values in the hydrogel phase, while using BSAMA led to increased stress. This study introduces a novel framework integrating experimental data, mechanical optimization, and numerical simulations to elucidate the viscoelastic behavior of hydrogel-based nanocomposite inks and multimaterial scaffolds. This research advances the development of next-generation biomaterials with improved durability and functionality, promoting regenerative medicine and personalized tissue engineering.