## 1 Introduction  
Ancient skeletal remains of \"upright\" humans reveal evidence of spinal diseases and deformities predating antiquity. It was [PERSON] (460-375 BC) who used the terms \"scoliosis\" and \"kyphosis\", along with \"lordosis\", to describe the deformities of the spine in his work _On the joints_[1]. The basic engineering principles of early spinal braces still apply to modern ones, such as three-point bending and inversion forces [2]. As of now, the most commonly used scoliosis braces are the Boston Brace and the Milwaukee Brace [3, 4, 5]. Both braces are manufactured using a combination of thermoplastics (polyethylene or polypropylene), foam liners, and straps. To manufacture the brace, the thermoplastic is heated to mold the plastic sheet into the shape of the patient's body, foam liners are placed in contact areas where the main pressure is applied, and then straps are used to adjust and secure the brace. The manufacturing process, especially the molding of the thermoplastic, is quite complicated and leaves much to be desired in terms of precision. Efforts are currently in progress to advance the design of modern spinal braces with a primary focus on ensuring patient comfort and usability. To achieve this goal, the integration of laser scanning is necessary for the design of personalized spinal braces. Laser scanning technology provides a noninvasive and precise means of capturing detailed anatomical information, making it valuable for custom product design in medical applications [6; 7]. This detailed digital representation serves as the dataset for the subsequent design phases. The ability to consider all torso nuances enables the creation of braces that are tailor made to accommodate the patient's anatomy. This personalized approach, facilitated by laser scanning, should not only enhance the efficacy of spinal braces but also contribute to heightened patient comfort and adherence. In recent years, 3D-printing technology has started to be experimented with in the orthopedic field. Some notable applications include the manufacturing of spinal braces, bone splints, and customized prosthetics [8; 9; 10; 11; 12; 13; 14; 15; 16]. Several researchers have proposed procedures integrating advanced design methods and additive manufacturing for the realization of lightweight, easy-to-use personalized braces. Among them, [PERSON] et al. [10] presented a comparative study using four different materials in the 3D-printing process and evaluated their performance to conclude which one is more suitable for a 3D-printed spinal brace. [PERSON] et al. [14] performed a study for the evaluation of the advantages and disadvantages of 3D-printed spinal braces in comparison to the traditional ones using different evaluation criteria. Among the many different parameters of the 3D-printing techniques a particularly important aspect refers to material selection. This much-needed parameter of the mechanical properties of 3D-printed polymers has been studied in [12; 13; 14; 15], also addressing the very significant issues of reliability and fatigue. Furthermore, [PERSON] et al. [16] compared the performance of three varied materials simulating a spinal brace in the finite element analysis software Abaqus. A necessary step towards optimizing the brace in terms of weight and comfort is the numerical modeling and simulation of its interaction with the patient's body using the finite element method, enabling the estimate of the developing deformations and stresses of the brace as well as the developing pressures on the body during the brace's use. For that purpose, the geometry, material properties, and interaction properties must be modeled. When addressing the simulation of boundary conditions, various simplified approaches employing pinned or fixed supports have been explored in previous works [16; 17]. However, this approach overestimates the local stresses in the vicinity of such supports.