Fabrication and Performance Analysis of Porous Metallic Structures for Load Bearing Implants and Drug Delivery

Abstract

The need for implants has been increasing due to increased medical complication and increase in average life expectancy. Use of metallic structures as load bearing implant has extensively increased since its invention in 1960. Solid metallic structures as implants have some limitations, such as lack of osseointegration and stress shielding. Lack of osseointegration hinders bone ingrowth which affects the long-term stability of implant. Stress shielding due to difference in Young s modulus of implant and host bone may lead to bone resorptions and loosening of implant. Use of metallic structures with uniform porosity also do not satisfy the biological and mechanical requirements for the implant. The architecture of natural bone shows transition from a porous (cancellous bone) to solid structure (cortical bone). According to the structure of natural bone, a structure with porosity gradient is proposed to show superior material response to external load and offer greater flexibility in terms of elastic modulus and architectural strength for implant application. newlineThe success of load-bearing implants and prostheses also depends on the materials used and their properties. Ti-6Al-4V titanium alloys have gained popularity due to their favorable properties, including excellent specific strength, lower modulus, superior biocompatibility, and higher corrosion resistance. However, titanium alloys are bio-inert in nature. Hence, incorporation of local drug delivery (LDD) system for pro-osteogenic effect will be advantageous in terms of bone ingrowth. Various growth promoters such as angiogenic factors (VEGF, FGF, TGF-and#946;), bone morphogenetic proteins (BMPs), and systemic factors (calcitonin and calcitriol) have been suggested by the researchers for LDD systems to accelerate local bone regeneration and repair. However, these growth promoters are costly and require special care to maintain their bioactivity. Therefore, osteogenic drugs like Simvastatin have emerged as a promising option for LDD systems. newline newline