Three-dimensional printing of a multi-material model of the knee joint

Three-dimensional (3D) printing is additive manufacturing technology, based on the deposition of material layer by layer for the building of a 3D object. The New 3D manufacturing technologies have evolved rapidly in recent years in diverse areas application such as automotive, aerospace and medical. Nowadays, 3D technology in healthcare becoming a viable solution for customized manufacture of 3D anatomical models with high dimensional accuracy and short production time. They are becoming increasingly popular and accessible. The design/manufacture of anatomical biomodels is based on several data acquisition techniques such as 3D modeling solids through computer-aided-design (CAD), Computed tomography (CT), Coherence tomography (OCT), magnetic resonance imaging (MRI) or 3D scanning of anatomical models. ShirleyRyan AbilityLab Research Hospital has a full-color multi-material 3D printer Stratasys J750™. It uses the Photopolymer jetting (PolyJet™ technology) for the production of highly realistic and functional 3D objects in a wide range of functional materials and colors with variable durometers. Materials and methods: Polygonal mesh files (*.hm) corresponding to a finite elements (FE) model of the right knee joint reported by Dhaher et al. 2014 were the basis of this study. The 3D model includes femur, tibia, patella, fibula, ligaments, articular cartilage, menisci, retinacula, patella and quadriceps tendons (PT-QT). From this, were designed/printed three biomodels achieving the following objectives; (1) Improvement of the 3D model of the right knee joint emulating the hierarchical structure of the collagen fibers matrix and design the paths to integrate strain sensors. (2) Anterior cruciate ligament reconstruction (ACL-R) biomodel manufacture and Pre-operative planning to improve ACL-R surgery outcomes, incorporating key surgical elements, such as orientation-architecture of the femoral/Tibial tunnels and bone-patella tendon-bone (BPTB) auto-graft dimensions reported by Dhaher et al. 2014. The surgical planning consider single bundle reconstruction and include a personalized surgical guide (SG) based on the anatomy of the PT (it used in the graft harvest). The SG requirements followed the indications reported by Grawe et al. 2014 with the aim to avoid graft tunnel length mismatch. (3) Total knee replacement (TKR) biomodel manufacture with custom design, adjustment and assembly of standard prosthetic components in the improved 3D model emulating a TKR procedure. A cruciate sacrificing implant (CS) with symmetric tibial bearing fixed was considered. The process of selection and matching of the print materials with the anatomical structures was based on analysis of the stiffness and elastic modulus of the different combinations of the Agilus30 printing material. Mechanical test followed ASTM test designation D412-C.