| Sumario: | Background: Stroke is one of the leading causes of acquired disability in adults, with upper limb spasticity being a common sequela that compromises motor functionality. Biomechanics plays a crucial role in developing effective assistive devices, highlighting the importance of technologies such as biomodels, which replicate limbs or organs in three dimensions to analyze pathophysiological conditions. Additive manufacturing, integrated with ComputerAided Design, Engineering, and Manufacturing (CAD/CAE/CAM) techniques, enables a digitized workflow in the development of assistive technologies. Among the methods for obtaining biomodel geometries found in literature, 3D scanning and parameterization stand out, allowing the fabrication of customized post-stroke orthoses that overcome the anatomical limitations of conventional methods. Objectives: Evaluate the feasibility and compare 3D scanning and parameterization methodologies on creating biomodels of post-stroke spastic upper limbs, applied to the production of customized orthoses via additive manufacturing. Materials and Methods: This project was approved by the Research Ethics Committee and by the Brazillian National Research Ethics Comission (CAAE No. 85355924.1.0000.5503). First, the geometry of the simulation of a spastic upper limb was obtained through 3D scanning with a Shinning Einstar scanner and parametric reconstruction via software (Make-Human and Blender), aiming to replicate it in a functional position, relevant for physiotherapeutic rehabilitation using orthoses. No poststroke patients were involved in the study, the scanned biomodel was created based on one of the coauthors’s arm simulating a spastic upper limb. The obtained digital models served as the basis for the 3D modeling of the respective orthoses, followed by structural analysis and shape optimization using the Finite Element Analysis (FEA) technique. Three-dimensional printing was performed using fused filament fabrication with Thermoplastic Polyurethane (TPU) for the biomodels and rigid thermoplastic Polylactic Acid (PLA) for the orthoses. Based on kinesiology concepts, a professional physiotherapist evaluated the biomechanical properties of the orthoses as a criterion for assessing the feasibility of the proposed methodology. Results: Three-dimensional printing provided satisfactory dimensional accuracy, with TPU ensuring the biomodels flexibility and physical integrity for clinical simulations, while PLA used in the orthoses provided the necessary rigidity and mechanical strength for rehabilitation. The digitized biomodel resulted in an orthosis with greater anatomical fidelity to the scanned user and a smoother 3D modeling process; however, the angles of the functional position were not fully maintained. Conversely, the parameterized biomodel exhibited better alignment with the functional position angles but was limited in representing all the anatomical features of a potential volunteer, such as anatomical accidents. Conclusions: The integration of CAD/CAE/CAM techniques in biomodel prototyping proved promising for clinical applications in post-stroke orthosis production. The 3D scanned biomodel ensured anatomical accuracy and ease of modeling, whereas the parameterized biomodel better maintained the angles required for the functional position. Combining both biomodeling techniques represents an alternative to optimize this process, ensuring anatomical fidelity and precise finger positioning. Future research should focus on refining modeling processes and clinically validating the orthoses, contributing to advances in biomechanical rehabilitation for post-stroke patients.
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