| Objective:1.To prepare the vancomycin-impregnated TCP as an antibiotic delivery system and to characterize its material properties in terms of setting time, compression strength and crystal structure. The release profiles of vancomycin in vitro and in vivo were determined, as well as microbiological activity and bone formation. 2. To observe infection controls when vancomycin-impregnated TCP was employed to manage hemiprosthetic hip joints infection in rabbits.Methods: 1.Preparation of vancomycin-impregnated TCP and its relative tests in vivo-in vitro.①The TCP was prepared using powder versus its liquid ratio of 3, and under the same method the vancomycin-impregnated TCP was prepared by powder containing vancomycin(1:20w/w) and liquid. ②The setting times of TCP and vancomycin- impregnated TCP were measured during preparing, then the compression strength and crystal structure of specimens were observed. ③The specimens of TCP and vancomycin- impregnated TCP were immersed in PBS which was incubated at 37℃ and was changed every 24 hours. At 1, 4, 7,10, 13, 16, 19, 22, 25 and 28 day , the concentrations of vancomycin in the elution fluids were determined by high performance liquid chromatography(HPLC). ④The specimens of TCP and vancomycin-impregnated TCP were placed on culture media of agar which had been inoculated 1.5×108CFU of MRSE, and the inhibitory zones were measured after incubated at 37℃ for 24 hours. Then the culture media were changed every 3 days and the inhibitory zones were measured and recorded at 1, 4, 7,10, 13, 16, 19, 22, 25 and 28 day. ⑤The specimens of vancomycin-impregnated TCP were implanted into femoral condyle of rabbits and the concentrations of vancomycin in adjacent bone tissues and blood serum were measured at 1, 4, 7,10, 13, 16, 19, 22, 25 and 28 day, and the bone formation of the specimens was investigated at 16,28 day. 2.Revision arthroplasty with vancomycin-impregnated TCP and gentamycin-PMMA or no delivery systems placed locally were employed to 36 rabbits with hemiprosthetic hip joints infection, which were divided into 3 groups with 12 in each group respectively. Animals were sacrificed 12W later, culturing of MRSE was performed andX-ray was taken, CRP, ESR and counts of WBC examined, as well histological changes were investigated. Results:1.The characteristics of vancomycin-impregnated TCP and its release profiles in vivo-in vitro. ①The initial time and final time of TCP were 5.4±0.6min and 15.5±1.3 min respectively, and the compression strength of which was 33.3±2.4MPa. The initial time and final time of vancomycin-impregnated TCP were 6.1±0.7min and 17.0±1.6min respectively, and the compression strength of which was 30.2±2.8MPa. No significant changes were observed between them(p>0.05). Crystals of TCP showed an irregular array with irregular space between them when observed through scanning electronic microscope, and no significant changes were observed when vancomycin was added into. ②The delivery of vancomycin from vancomycin-impregnated TCP showed a burst one when vancomycin-impregnated TCP immersed in PBS at 1st day, then it showed a rapid decrease, but still maintained a mean concentration of vancomycin in elution fluids about 11.6±1.9μg·ml-1 at 28thday, which was greater than MIC for MRSE(MIC≈4μg·ml-1). While no vancomycin was detected in the elution fluids of TCP. ③Vancomycin-impregnated TCP showed an inhibitory effect for MRSE in vitro and the inhibitory zone was about 27.1±1.6mm in diameter at 1st day, which reduced gradually as the procedure went on and an obvious one could be measured at 28th day, while for TCP no inhibitory zones were observed. ④The concentrations of vancomycin in adjacent bone tissues reached their high at 1st day and decreased gradually, which was still greater than MIC for MRSE at 28th day, while vancomycin was detected in blood serum only at 1st day. New bone formation had been observed when vancomycin-impregnated TCP had been implanted into the femoral condyle for 16 and 28 days. 2. Four weeks after 1×108 CF...
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