Authors: A. Heijink, M. Rouse, D. Lewallen, M. Yaszemski, R. Patel, AD Hanssen
Title: Compatibilty of vancomycin with Osteo-set, DBX-putty, Collagraft and Polymethylmethacrylate (PMMA).
Purpose: PMMA is currently used as an antibiotic delivery system for treatment of bone and joint infections. PMMA may be less than optimal because it is not biodegradable and not all of the antimicrobial loaded is released. The purpose of our study was to determine the compatibility of vancomycin with: Osteo-Set® (Wright Medical), DBX-putty®(MTF), Collagraft® (Zimmer) and polymethylmathacrylate (PMMA) bone cement (Howmedica). We measured the antimicrobial activity of vancomycin loaded Osteo-Set, DBX, Collagraft or PMMA.
Methods: Osteo-Set® beads were prepared by adding vancomycin to the powder component of Osteo-Set for a concentration of 7.5% (w/w) of powder and solvent together. DBX® was mixed with 7.5% vancomycin (w/w). Collagraft® strips were ground to a fine powder and mixed with saline 1:1 (w/v). Vancomycin was added to the paste to a concentration of 7.5% (w/w). PMMA beads were prepared by adding vancomycin to the powder component of PMMA to a concentration of 7.5% (w/w). Six independently prepared beads of each formulation were tested. The antibiotic loaded samples were allowed to set up for 2 hrs, homogenized in 5 mL of saline and incubated for 24 hrs at 37oC to elute from carrier material. Eluates were assayed in triplicate for vancomycin concentration by microbiological assay.
Results: Results were expressed as mean percentage of vancomycin recovered from each material
± standard deviation.
Discussion: We recovered 73 - 100% of vancomycin loaded into Osteo-Set, DBX-putty or powdered Collagraft.
Significance: Vancomycin is compatible in vitro with all compounds tested. Osteo-Set, DBX-putty or powdered Collagraft are biodegradable and readily available to the surgeon for clinician directed applications. They may be effective antimicrobial delivery depot compounds. Further studies of antimicrobial release kinetics and clinical activity may be warranted.