Molecular engineering of an orthopaedic implant: from bench to bedside

The use of metallic implants has revolutionised the practice of orthopaedic surgery. While the safety and biocompatibility of these devices are excellent, a small percentage becomes infected. These infections are due to the formation of a biofilm that harbours bacteria encased in a complex extracellular matrix. The matrix serves as a barrier to immune surveillance as well as limiting the biocidal effects of systemic and local antibiotics. The objective of the review is to describe a novel approach to controlling implant infection using an antibiotic that is linked to titanium through a self-assembled monolayer of siloxy amines. We show that the hybrid-engineered surface is stable, biocompatible and resists colonisation by bacterial species most commonly associated with implant-related infections. Studies with rodent bone infection models suggest that the engineered titanium surface prevents bone infection. Results of a very recent investigation utilising a sheep model of infection indicate that the titanium-tethered antibiotic controls infection without compromising bone formation and remodelling. From all of these perspectives, the tethered antibiotic holds promise of providing a novel and practical approach to reducing implant-associated infections.