Investigation of applicability functionally graded hybrid scaffold structures on femoral component

Nowadays, additive manufacturing (AM) methods are preferred due to insufficient production methods in aviation, space, defense industry and biomedical fields. With the use of this method, it becomes possible to produce different geometries and pore dimensions. Especially in order to increase the services life of joint prostheses used in biomedical applications, scaffold structures are produced with AM methods. In this study, the applicability of functional graded hybrid (FGH) scaffold structures to the femoral component was investigated. Within the scope of the experiments, the triple periodic minimal surface (TPMS)-based primitive-gyroid (P-G), body centred cubic -gyroid (BCC-G) and primitive-body centered cubic (P-BCC) scaffold structures are designed. After the design, hybrid scaffold structures were produced using the selective laser melting (SLM) method at functional grading (FG) percentage (20%-30%-40%-50%) for four different porosity coefficients. In order to determine the mechanical performance of the scaffold structures, single-axis compression tests were performed and compared with the results of finite element analysis (FEA). In addition, the scanning electron microscope (SEM) and micro-CT images were taken in order to determine production defects and sensitivity. Finally, cell growth experiments were performed for the top three FGH scaffold structure in terms of mechanical performance. In the compression test results obtained, the highest elastic modulus was in the P-BCC hybrid scaffold structure, while the energy absorption ability was measured in the BCC-G hybrid scaffold structure. On the other hand, in the microscope images taken after production, it was determined that both superficial defects appeared due to the bonded particle, stair effect and mass agglomeration, and it adversely affected the dimensional accuracy. Finally, when the cell growth results were evaluated, it was determined that the cell viability was above 80% in all P-G, P-BCC and BCC-G hybrid scaffold structures. As a result, it is suggested that the service life of knee joint prostheses can be increased with the application of FDH scaffold structures to the femoral component.