Architected materials are increasingly applied in form of lattice structures to biomedical implant design for the purpose of optimizing the implant’s biomechanical properties. Since the porous design of the lattice structures affects the resulting properties of the implant, its parameters are being investigated by numerous research articles. The design-related parameters of the unit cells for a strut-architected material are mainly the pore size and the strut thickness. Until today, researchers have not been able to decide on the perfect values of the unit cell parameters for the osseointegration process and tissue regeneration. Based on in vivo and in vitro experiments conducted in the field, researchers have suggested a range of values for the parameters of the lattice structures where osseointegration is in acceptable status. The present study presents a comprehensive review of the research carried out until today, experimenting and proposing the optimum unit cell parameters to generate the most suitable lattice structure for the osseointegration procedure presented in orthopedic applications. Additional recommendations, research gaps, and instructions to improve the selection process of the unit cell parameters are also discussed.
The development of medical implants is an ongoing process pursued by many studies in the biomedical field. The focus is on enhancing the structure of the implants to improve their biomechanical properties, thus reducing the imperfections for the patient and increasing the lifespan of the prosthesis. The purpose of this study was to investigate the effects of different lattice structures under laboratory conditions and in a numerical manner to choose the best unit cell design, able to generate a structure as close to that of human bone as possible. Four types of unit cell were designed using the ANSYS software and investigated through comparison between the results of laboratory compression tests and those of the finite element simulation. Three samples of each unit cell type were 3D printed, using direct metal laser sintering technology, and tested according to the ISO standards. Ti6Al4V was selected as the material for the samples. Stress–strain characteristics were determined, and the effective Young’s modulus was calculated. Detailed comparative analysis was conducted between the laboratory and the numerical results. The average Young’s modulus values were 11 GPa, 9 GPa, and 8 GPa for the Octahedral lattice type, both the 3D lattice infill type and the double-pyramid lattice and face diagonals type, and the double-pyramid lattice with cross type, respectively. The deviation between the lab results and the simulated ones was up to 10%. Our results show how each type of unit cell structure is suitable for each specific type of human bone.
The deviation between the designed lattice structures and the 3D-printed ones has been studied in this research. Three types of lattice structures were designed using the SpaceClaim application in the ANSYS software and then fabricated using Direct Metal Laser Sintering (DMLS) via EOS M 290 3D printer. Considering the orthopedic application, Ti6Al4V alloy of grade 23 was selected as a material for all samples of the structures. A thorough comparison was done on the volume, mass, and porosity to effectively map the possible deviations between the designed and the printed version. The shape accuracy of the 3D printing process was discussed during the study. As the complexity of the shape of the unit cell increases, the accuracy of the printing process becomes lower. Dimensional accuracy in the XY plane is higher than accuracy in the Z plane. Simple unit cell shape was proven to be more accurate in the 3D printing process.
The research is dedicated to determine one of the most important mechanical properties which is the Young's modulus. Its value is crucial for clearly explaining and understanding the results of any mechanical loading experiment. Three cylindrical samples of 15 mm height and 7.5 mm diameter were designed using SpaceClaim application in the ANSYS Software and then 3D printed using Direct Metal Laser Sintering via EOS M 290 3D printer. The specimens were then tested under compression in order to determine the value of the Young's modulus for titanium alloy of grade 23 (Ti, Al, V, O, N, C, H, Fe, Y). The finite element method was executed using ANSYS mechanical to run a comparison between laboratory results with nominal results of the Young's modulus. Young's modulus value is affected by the 3D printing accuracy and quality, the material's quality as well; however, the deviation is within 10%.
Additive manufacturing (AM) is a process in which the product is composed of overlapping layers of a material that is added using devices such as 3D printers. Its process has been evolving for decades and nowadays it can be used for several applications and with different materials. One modern usage is for medical and dental purposes. Since it became possible to print metal, it has been a good solution for bone implants, once it must be done with biomaterials and can now replicate the bone structure, for that unit cells should compose the implant. Both conditions are now possible to be achieved by AM, and the current study will analyze, using finite element method, the possibilities to create specimens for tests which the final product would result in a 3D printed bone implant.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.