Biodegradable Drug Delivery Systems for Gentamicin Release and Treatment of Synovial Membrane Infection

OBJECTIVE: This study investigated two biodegradable drug delivery systems (BDDS) for elution of gentamicin and elimination of synovial membrane infection. STUDY DESIGN: The effect of BDDS on control and infected synovial explants was determined. ANIMALS OR SAMPLE POPULATION: Synovial explants from four adult equine cadavers. METHODS: First, BDDS were placed in phosphate buffered saline for 14 days. Eluent was tested for gentamicin concentration (G) and bioactivity. Second, synovial explants were divided into four groups (n = 14/group): Group 1 (control); Group 2 (infected control) 405 cfu Staphylococcus aureus added at 6 hours; Group 3 (antibiotic BDDS [Ab-BDDS]) Ab-BDDS added at 24 hours; Group 4 (infected Ab-BDDS) 405 cfu S. aureus added at 6 hours, Ab-BDDS added at 24 hours. Both types of Ab-BDDS were used (n = 7/type/group). Explants were incubated in standard medium for 4 days. Medium was cultured and analyzed for (G) and hyaluronic acid concentration (HA). Explants were analyzed for viability and morphologic changes. RESULTS: The Ab-BDDS released >500 microg/mL of active gentamicin for 10 days. In Group 3, infection was eliminated within 24 hours, but histologic scores did not return to normal. Viability was significantly reduced by infection, but if eliminated, viability tended to return to normal. In Group 3, the Ab-BDDS had no significant effect on viability or (HA). Histopathologic scores were significantly higher for infected synovium. Infection, even if treated, significantly reduced (HA). CONCLUSIONS: Both Ab-BDDS eliminated infection within 24 hours. However, synovial morphology, viability and function did not return to normal. CLINICAL RELEVANCE: The Ab-BDDS may be useful for treatment of synovial membrane infection.