2004 Abstract : CS 2

Authors: Javad Parvizi MD, FRCS, Noreen J. Hickok PhD, Eric Wickstrom PhD, Allen R. Zeiger PhD, James J. Purtill MD, Peter F. Sharkey MD, William J. Hozack MD, Irving M. Shapiro PhD, Christopher S. Adams PhD, Richard H. Rothman MD, PhD

Title: Titanium Surface with Biologic Activity Against Infection

Addresses :Department of Orthopedic Research, Rothman Institute of Orthopedics, Thomas Jefferson University, Philadelphia, PA 19107

Purpose: Despite immense improvements, periprosthetic infection continues to compromise the result of otherwise successful joint arthroplasty. There are various limitations in the management of periprosthetic infection, the most important of which is the inability to deliver antibiotics to the local tissue without the need for intravenous administration. The purpose of this study is to repoprt the result of a novel series of experiments during which covalent bonding of antibiotics to the surface of titanium was achioeved.

Methods: Titanium particles were reacted with aminopropyltriethoxy silane (APTS) to yield a surface suitable for solid-phase Fmoc couplingd addition of aminoethoxyacetic acid linkers (AEEA), followed by FMOC Fmoc coupling with of vancomycin. Based on coupling efficiencies, greater than 50% of available Ti-APTS were derivatized with AEEA-vancomycin. AdditionBonding of vancomycin to the surface was tested using by Matrix Assisted Laser Desorption Time of Flight (MALDI-TOF) mass spectrometry using a chamber, with laser power of ? at l=?. Vancomycin activity was tested using a [ 14C]-peptidoglycan binding assay and by the ability to inhibit bacterial growth or kill adherent Staphylococcus aureusbacteria, as measured by a proliferation colony formation assay and the Live/Dead BacLight Assay (Molecular Probes).

Results: Covalent bonding of vancomycin via AEEA and silane linkers to the Ti support was confirmed by The experiments utilizing Matrix Assisted Laser Desorption-Time of Flight (MALDI-TOF) confirmed that coupling covalent bonding of vancomycin via AEEA and silane linkers to the Ti support was achieved. The presence of active vancomycin bound to the APTS-Ti was further confirmed by the specific binding of its ligand, [14C]-D-Ala-D-Ala. S. aureus cultured on Vvancomycin-APTS-Ti showed greatly decreased viability by differential membrane/nuclear staining (Live/Dead Bac Light Assay, Molecular Probes) and decreased colony formation. In contrast, When S. aureus was incubatedcultured on with APTS-Ti, organisms stained as viable organisms and exhibited continued to proliferategreater colony formation and remain viable as determined by Live staining technique (?Noreen), with only a few dead organisms. In contrast, almost all S. aureus incubated with VAN-Ti were completely eradicated. This confirmed that theIn summary, it is possible to covalently bond vancomycin presence of organisms lead to cleavage of APTS-Ti covalently bound to APTS-Ti such that it and successful release of vancomycinretaineds its bactericidal activity and is present at concentrations that are bactericidal upon repeated challenges.

Discussion: Recent advances in delivery of surgical care has lead to signifiacnt reduction in the incidence of periprosthetis fracture from the historical 9-10% to about 1-2%. Ther current strategies to treat periprosthetic infection,however, remains imperfect. The inability to prevent infection or to eradicate organisms in all cases of infection, highlight some of these limitations. Furthermore, the surgical treatment of periprosthetc fracture under current circumstances carries immense psychosocial and economic costs. Improved techniques for prevention and treatment of periprosthetic infection is needed. This study has accomplished a novel method of attaching antibiotics to the surface of implants using stable covalent bonds that can be directly modulted.

Significance: This technology holds a great promise for manufacturing of `smart' implants that can be self-protective against periprosthetic infection or be used for the treatment of periprosthetic infection when they occur.