Topographic Features Retained after Antibiotic Modification of Ti Alloy Surfaces: Retention of Topography with Attachment of Antibiotics

Periprosthetic infection is increasingly prevalent in orthopaedics with infection rates of 2% to 15% after total hip arthroplasty. To effectively decrease bacterial attachment, colonization, and subsequent development of periprosthetic infection, we previously described a method to covalently bond vancomycin to smooth Ti alloy surfaces. To attach vancomycin, the Ti surface is first passivated to create a fresh oxide layer. Previously, passivation has been achieved with an H₂SO₄/H₂O₂ etch that can destroy the topography of the underlying implant. Passivation by hydrothermal aging as well as by H₂SO₄/H₂O₂ incubation produced a robust oxide layer, but only hydrothermal aging left the geometry unaltered. These hydrothermally passivated Kirschner wires and smooth or beaded Ti surfaces were chemically coupled with vancomycin. Antibiotic-coupled samples representing all three geometries were uniformly covered with antibiotic, resisted colonization by Staphylococcus aureus for longer than 8 hours, and retained their biocompatibility as assessed by normal attachment and morphology of preosteocytic MLO-A5 cells. Using this technique, we believe it is possible to passivate many complex implant designs/geometries as a first step toward covalent bonding of antibiotics or other bioactive factors.