Proposes Geometric Accuracy and Surface Roughness Estimation of Anatomical Models of the Pelvic Area Manufactured Using a Material Extrusion Additive Technique  
[PERSON]  
1 Department of Manufacturing Techniques and Automation, Rzeszow University of Technology, 35-959 Rzeszow, Poland; [EMAIL_ADDRESS]  
2 Orthopedics and Traumatology Department, University Hospital, 35-301 Rzeszow, Poland; [EMAIL_ADDRESS]  
technology in the field of orthopedics have led to significant advances in the area of research into hip replacement design and manufacturing methods [9]. To ensure the best fit for individual patients, doctors increasingly seek custom-made products manufactured for a specific patient [10]. Because of the unique geometry of models of anatomical structures, surgical templates, or implants, additive methods are often used in manufacturing [11; 12]. However, such devices must be characterized by a certain accuracy of manufacture. So far, no specific procedures have been developed for controlling the geometric accuracy and surface roughness of anatomical models made by additive methods for planning procedures in the hip bone area [11; 13; 14]. During anatomical models' reconstruction and manufacturing stages, errors can affect geometrical accuracy [15; 16; 17] and surface roughness [18]. Currently, the ISO/ASTM TR 52916 [19], ISO/IEC 3532-1 [20], and ISO/IEC 3532-2 [21] standards offer fundamental information on errors occurring during the diagnosis and modeling of anatomical structures. Literature also includes studies that estimate the errors encountered during diagnosing and modeling anatomical structures within the hip joint [22; 23]. Furthermore, some studies assess the accuracy of model manufacturing using additive methods [24; 25]. Presently, additive methods, specifically MEX, are widely used in manufacturing models for hip surgery planning [25; 26; 27; 28]. To ensure the accuracy and quality of the manufactured model surface using this method, special attention should be given to factors such as the temperature around the 3D printer workspace [29], the nozzle and the work platform [29], the layer thickness [30; 31], the manufacturing speed [32], the orientation of the model in the 3D printer space [33; 34], the degree of filling of the model [35], and the type of material used in manufacturing process. In the evaluation process of an anatomical structure model's geometrical accuracy and surface roughness, contact [17; 18; 36; 37] and optical [25; 38; 39] measurement tools and systems are commonly used. It is crucial to reliably assess the metrological accuracy of the manufactured anatomical structure, as it provides comprehensive information about the precision of the final model's development. This information can significantly enhance the accuracy of procedure planning. Currently, the guidelines outlined in ISO/ASTM 52902 [40] are utilized to determine the accuracy of models produced using additive methods. The standard also provides information on selecting CAI systems. However, it's important to note that ISO/ASTM 52902 only offers suggestions for dimensional evaluation and partially covers the evaluation of profile parameters of surface roughness. Unfortunately, ISO/ASTM 52902 does not address the selection of systems and measurement parameters when evaluating anatomical structure models' geometrical accuracy and surface roughness. It is essential to include discussions on the potential challenges in inspecting the accuracy of anatomical models manufactured using MEX additive methods. This research aspect is crucial, especially considering that, based on the current literature, models of anatomical structures made of polymeric materials are most commonly used for planning procedures within the hip joint area. These materials have different properties, often making conducting a reliable metrological evaluation during measurement difficult. The most frequently used material in manufacturing models of anatomical structures of the hip joint is PLA [15; 16; 18; 41].