Sustained drug release from surface modified UHMWPE for acetabular cup lining in total hip implant

Abstract

Despite sterilization and aseptic procedure, bacterial infection remains a key challenge in total hip arthroplasties. This fact emphasizes the urgent need for development of new implant systems, which should releases the drug in a controlled manner without sparing its mechanical and tribological properties. In this study, the lining material of the acetabular cup, in total hip implant, has been modified for sustained release of drugs, which should be available throughout the site of implantation to fight the post-operation bacterial infection. A modified solvent based etching and lypolization technique has been used to engineer a thin porous surface layer on ultra-high molecular weight polyethylene (UHMWPE) substrate, which is clinically used as acetabular-cup lining. Gentamicin loaded chitosan solution has been impregnated into modified surface, which suitably gets released over a long period. The main challenge was to keep the mechanical and tribological behavior of this lining material unaffected after the modification. Modified surface offers reduction in friction coefficient and wear rate, by 26% and 19%, respectively, in comparison to UHMWPE, which is encouraging towards the intended application. Hardness and elastic modulus decreases slightly, by 27% and 20%, respectively, possibly due to improper impregnation of chitosan inside porous surface. However, after drug release, the modified surface regains the mechanical and tribological behavior similar to unmodified UHMWPE. Surface modified UHMWPE have shown an impressive release profile for drug up to 26days and released >94.11% of the total drug content. In vitro antibacterial tests have proven that the modified surface of UHMWPE can effectively release the drug and fight against infection. This surface engineered acetabular cup lining is a promising candidate in the area of drug eluting implant, which can bring a significant advancement to the functionality of commercially used orthopedic implants by providing inherent capacity for fighting infections in-vivo.