High active local levels of vancomycin without nephrotoxicity released from impacted bone allografts in 20 revision hip arthroplasties

BACKGROUND: Cancellous bone can act as a delivery vehicle for vancomycin without impairment of graft incorporation. However, local and systemic antibiotic levels, biological activity of vancomycin, interaction with antibiotic-loaded cement, and also nephrotoxicity of these composites have not yet been studied clinically. MATERIAL AND METHODS: Blood, drainage and urine samples of 20 consecutive patients undergoing revision total hip arthroplasties with impaction grafting technique utilizing 1 g of vancomycin per femoral head were studied. Plain PMMA cement was used in 10 cases, while PMMA with gentamycin was used in 5 cases and tobramycin was used in the remaining 5 cases. Biological activity of vancomycin was studied using kinetic killing curves in three ATCC organisms (methicillin-sensitive Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosas). Quantification was done with fluorescent polarized immunoassay. Renal function was evaluated with preoperative and postoperative urea and creatinine. RESULTS: Local active bactericidal levels of vancomycin reached 1400 microg/mL (average 5-point level = 367 microg/mL) without nephrotoxicity. Vancomycin was present in urine until the fifteenth day. Both aminoglycosides in the cement had activity against Pseudomonas aeruginosas. INTERPRETATION: Local levels of vancomycin were 35 times greater than the highest levels reported with vancomycin-loaded PMMA. A synergistic effect was observed between vancomycin released from impacted allografts and aminoglycoside-loaded PMMA.