Brace Simulation for Patients with Scoliosis: Biomechanical Comparison with Three Different Polymeric Materials

Abstract

ne of the wonders of creation in humans is symmetry as this symmetry brings about balance and beauty. The human spinal cord, as the axis of this symmetry, has its own defining principles and curvature. The spinal cord is vital in withstanding body weight and focused pressure, as well as maintaining the nervous system and performing different body movements.One of the consequences of modern life is the appearance of conditional disorders and pain in musculoskeletal structures especially in young people. These disorders are caused by several factors such as motion poverty, muscle imbalances, individual physical characteristics, physical maturity especially rapid bone growth, nutrition disorders especially vitamin D deficiency, long periods of sitting, inappropriate ways of carrying bags, improper motion patterns, psychological characteristics and also congenital factors. These problems cause illnesses such as kyphosis, which is as a uniform arch on the top of spinal cord, and musculoskeletal disorders, such as scoliosis, which may appear as a unilateral deviation (C-form deviation) or as a bilateral deviation (S-form deviation) of the spinal cord. 1The International Scientific Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT) recommends the following treatments based on the Cobb angle. However, individual treatment may vary depending on speed of progression and remaining skeletal growth (< 20°:

Numerical Modeling and Nonlinear Finite Element Analysis of Conventional and 3D-Printed Spinal Braces

“…In a study by Yun Hwan et al [23], the elastic properties of polypropylene/ultra-high molecular weight polyethylene fiber were estimated, yielding a calculated value of approximately 1325 MPa. Additionally, the mechanical properties of materials used in traditional braces have been identified through experimental investigations in various studies [16,17,23,24]. One of the key objectives of this study is to conduct a comparative analysis between traditional brace materials and those produced through additive manufacturing, particularly utilizing 3D-printed PLA.…”

“…There are three potential sources of nonlinearity in structural engineering simulations, material, geometry, and boundary condition nonlinearity, corresponding, respectively, to cases where stresses exceed the linear part of the material law, large deformations develop so that the deformed geometry differs substantially from the undeformed one, and when boundary conditions change during the analysis. The loads and stresses that the brace is subjected to in its daily use by a patient do not usually produce significant stresses of the material [16,[27][28][29], while the developing deformations are also limited by the patient's body. For this reason, the prevailing type of nonlinearity is the one of the brace's boundary conditions, namely its interaction with the patient's body, which is described by the nonlinear pressure-overclosure chart of Figure 6.…”

“…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.…”

“…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, Mafi et al [16] compared the performance of three varied materials simulating a spinal brace in the finite element analysis software Abaqus.…”

“…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.…”