Surface Modified Metallic Orthopedic Implant for Sustained Drug Release and Osteocompatibility

Designing implants with good antibacterial activity and simultaneously providing a platform for osteoblast adhesion is a challenge for researchers. All metallic implants, currently in use, are biocompatible but bioinert. This may lead to a weak interface with the bone and cause asceptic loosening. The aim of the present study is designing an implant with good antibacterial activity and simultaneously providing a platform for osteoblast adhesion. This is achieved by surface engineering of the currently used metallic implants without affecting their mechanical properties. The FDA approved plasma spraying technique is utilized to synthesize interconnected microporous bioactive hydroxyapatite (HA) coating on the Ti-6Al-4 V implant surface. The modified implant surface is impregnated with drug (gentamicin) loaded biodegradable polymer (chitosan) through a customized vacuum impregnation process. During impregnation, drug loaded polymer filled the pores of coating while leaving the rest of the HA surface exposed to promote osteoconductivity. The hardness and elastic modulus of the HA coating showed insignificant changes after impregnation with the drug loaded polymer, while the fracture toughness is improved by ∼42%. In vitro drug release studies have revealed a sustained release up to 180 h, with an ideal initial burst release. The drug loaded surfaces have also shown very efficient antibacterial activity against S. aureus, even after 5 days of incubation. Further, the modified surfaces have shown excellent osteocompatibility, due to the presence of the exposed HA coated surface. Thus, the surface modified implants, with a unique combination of antibacterial activity, osteocompatibility, and improved fracture toughness, have promising potential applications in orthopedics.