Review on Hydroxyapatite-Based Coatings as Antibiotic Delivery System on Bone Graft Substitution for Controlling Infection in Orthopedic Surgery

The comparisons of ionic substitutions and antibiotics in the form of coated- hydroxyapatite (HA) on orthopedic implants were reported in this review article. The antibiotic-coated HA implants are effective in many practical applications such as incidence of femoral pain, osteolysis of femur, reduction of healing time, and simultaneous growth of new bone on the implant. The metals like Cupper (Cu), Magnesium (Mg), silver (Ag), Strontium (Sr) & Zinc (Zn), which are essential in the body skeleton, are replaced in the Ca site, killing the bacteria by releasing the metal surface ions and the internal ions of the solution. The ion-substituted HA leads to the antibacterial activity of the compound without the antibiotic side effects. The ionic substitutions have shown a slower release time than chemical antibiotics. Doping of the Mg 2+ and Ag + ions indicated better behavior in removing the E. coli and S. aureus bacteria. Both of them are substituted in the Ca site of the HA. But F − ions are sited in the place of OH − in HA and usually show osteogenic and antibacterial activity when used in orthopedic fixators. At last, the Si 4+ ions are substituted in the P 4+ site that showed osteogenic activity. Our finding confirmed the more successful antibacterial activity of ion-substituted HA compared to the synthetic antibiotic-coated-HA implant in orthopedic surgery.