Recently there is a growing interest in the fabrication of novel structures to mimic multiple tissues and tissue interfaces on the same implant, such as implants with gradients in porosity and pore sizes that will allow on one side of the implant high vascularization and direct osteogenesis, while promoting osteochondral ossification on the other.
In the current context, innovative designs such as functionally graded acetabular shells with open porosity on one side (in contact with the bone) to improve cell-material interactions and a hard ceramic coating on the other side (in contact with UHMWPE liner) to reduce liner wear, can significantly improve the implant's in vivo life. While creating a hard/low friction ceramic surface on metal substrates seems plausible, there is a possibility of delamination or cracking due to the mismatch in elastic moduli, coefficient of thermal expansion and hardness between the ceramic coating and the metal substrate. Although functionally graded coatings (FGCs) can overcome such difficulties, it is difficult, if not impossible, to fabricate net shape implants/structures with spatial gradation in composition and structure (porosity) with conventional processing routes.
WSU inventors have overcome this fabrication issue using Laser Engineering Net Shaping (LENSÔ) - a solid freeform technique, to fabricate compositionally and structurally graded Ti-TiO2 structures with sound interface between the two materials and high surface hardness. Such gradient structures provide useful mechanical support for the wear resistant, low friction exterior layers, and minimize the likelihood of localized Hertzian failure during implant service.
Applications and Advantages
Offers an improved process to fabricate net shape implants/structures with desired characteristics (e.g. spatial gradation in composition and structure (porosity), biocompatibility, and excellent wear resistance)
US Patent Application Filed 14/378, 160