3D finite element analysis of porous Ti-based alloy prostheses.

In this paper, novel designs of porous acetabular cups are created and tested with 3D finite element analysis (FEA). The aim is to develop a porous acetabular cup with low effective radial stiffness of the structure, which will be near to the architectural and mechanical behavior of the natural bone. For the realization of this research, a 3D-scanner technology was used for obtaining a 3D-CAD model of the pelvis bone, a 3D-CAD software for creating a porous acetabular cup, and a 3D-FEA software for virtual testing of a novel design of the porous acetabular cup. The results obtained from this research reveal that a porous acetabular cup from Ti-based alloys with 60 ± 5% porosity has the mechanical behavior and effective radial stiffness (Young's modulus in radial direction) that meet and exceed the required properties of the natural bone. The virtual testing with 3D-FEA of a novel design with porous structure during the very early stage of the design and the development of orthopedic implants, enables obtaining a new or improved biomedical implant for a relatively short time and reduced price.

Bioactive glass enhances bone ingrowth into the porous titanium coating on orthopaedic implants.

PURPOSE: The aim of the study was to verify the ability of nanoparticulate bioactive glass (BAG) to infiltrate into the porous titanium (Ti) layer on Ti-based implants to promote osseointegration. METHODS: The porous titanium layer on Ti-based implants was impregnated with nanoparticulate BAG. The implants without or with BAG were implanted bilaterally in tibial holes of ten New Zealand white rabbits. The rabbits were sacrificed after ten weeks for examinations. Beside histological examination, EDXS analysis of polished cross-sections of explanted implants was also performed with the aim to quantitatively evaluate the bone-to-pore contact and bone-in-pore ratio. RESULTS: After ten weeks, EDXS analyses of cross-sections of the explanted implants confirmed that bioactive glass was fully resorbed and that the pores throughout the thickness of the porous titanium layer were to a large extent filled with a new bone. In the absence of bioactive glass, only the outer part of the porous layer was filled with bone. The implants without BAG in the porous Ti-layer exhibited similar bone-to-pore contact, while significant improvement of bone ingrowth into the pores was observed for the implants with BAG (38%), as opposed to those without it (22%). CONCLUSION: This study confirmed that the nanoparticulate bioactive glass within the porous titanium surface layer on implants promotes osseointegration and stimulates the formation of bone within the pores.