Bioactive Hybrid Material Surface Treatments for Infection Resistant Implants without Drugs

In the civilian population, infection rates of orthopaedic implants have come down to around 2%, with re-infection rates as high as 30%. However, this is amplified with combat injuries where high-energy and contaminated wounds cause infection rates as high as 40-50%. The goals of orthopedic injury management are to prevent infection, promote fracture healing, and restore function. Titanium and stainless steel implants have been the standard for fracture fixation. Biocompatibility of these devices is attributed to the formation of a stable surface oxide layer called passivation. Transitional metals (Ti, Zr, Ta etc.) are known for their ability to form these passive oxide layers which are also bioactive during implantation. However, these materials do not actively resist infection

Here we explored the influence of implant grade non-resorbable polymer hybridization of transitional metals on cellular bioresponses. Doping with noble metal oxides was also used to impart additional antibacterial properties. We used a wet chemistry, metal-organic synthesis route to form coatings of various transitional metal oxide and polymer hybrids on the bottom of cell culture microplates. Hundreds of coatings were rapidly screened for bacterial and human cell growth and adhesion.

A range of compositions were identified which resisted bacterial growth, while facilitating health soft-tissue and bone cell growth. These materials were sent out for standard ISO biocompatibility and ASTM antimicrobial tests on implant grade titanium coupons in preparation for a large animal study. The blending of metal, ceramic and polymer biomaterials allowed us to control several bioactive properties independently and influence cellular proliferation and adhesion in a dose dependent manner. These materials show promise for imparting bioactivity and for use as controlled delivery matrices for orthopaedic trauma devices.