In vitro elution characteristics of vancomycin in a composite calcium phosphate/calcium sulfate bone substitute.
Academic Article
Overview
abstract
BACKGROUND: Periprosthetic joint infection is a particularly difficult orthopedic problem, complicating a growing number of revision procedures. Joint debridement and systemic antibiotics are the mainstay of treatment, yet difficulty remains in maintaining a minimum inhibitory concentration of antibiotic at the localized site of infection. STUDY AIMS: This study analyzes the elution characteristics of a 40%bwt calcium phosphate-60%bwt calcium sulfate composite, at varying concentrations of vancomycin. METHODS: Four groups of varying concentrations of vancomycin (2.63%bwt, 5.13%, 9.76%, and 17.78%) were mixed with one pack of the composite cement. At designated time intervals up to 28 days, the antibiotic concentration was detected using fluorescence polarization immunoassay and the elution trends compared. RESULTS: The elution rate of each of the four groups decreased over time. At almost all of the intervals, the elution rates of the higher concentration groups were significantly higher than the lower concentration groups (P < 0.05). CONCLUSIONS: Calcium sulfate reabsorbs over a prolonged period, producing porosity which allows for new bone ingrowth through occupation of osteoprogenitor cells and osteoblasts; while calcium phosphate acts as a long-term osteoconductive matrix. CLINICAL RELEVANCE: The results of this study suggest that vancomycin can be mixed affectively with a calcium sulfate/phosphate composite, both maintaining stability and eluting gradually over a clinically relevant period of time.
