Thurs., 10/13/11 Basic Science, Paper #33, 4:18 pm OTA-2011
Effect of Negative-Pressure Wound Therapy on the Elution of Antibiotics from Polymethylmethacrylate Beads in a Porcine Simulated Open Femur Fracture Model
Thomas M. Large, MD1; Geoffrey Douglas, MD2; Gregory Erickson, MD1;
J. Kevin Grayson, DVM, PhD2;
1Dept. of Orthopaedic Surgery,
2Clinical Investigation Facility, David Grant Medical Center, Travis AFB,
South Bend, Indiana, USA
Purpose: There are few data on the simultaneous use of antibiotic-impregnated polymethylmethacrylate (PMMA) beads and negative-pressure wound therapy (NPWT). Our objective was to determine whether NPWT affects antibiotic concentrations in simulated femur fractures treated with antibiotic-impregnated PMMA beads and whether fascial closure between beads and sponge affects the outcome.
Methods: PMMA beads containing vancomycin and tobramycin were placed adjacent to bilateral corticotomies created in 20 anesthetized pigs. In one leg, NPWT was applied with the sponge either in direct contact with the beads, or superficial to reapproximated fascia lata. The contralateral wound was conventionally closed. Vancomycin and tobramycin concentrations in wound drainage were measured every 12 hours for 72 hours, and tobramycin levels were measured in periosteal tissue obtained at 72 hours.
Results: Drainage vancomycin and tobramycin concentrations were highest at 12 hours and fell rapidly by 24 hours, but remained steady thereafter. At each 12-hour interval, there were no significant differences in the vancomycin and tobramycin concentrations between NPWT and control wound drainage, although whether the fascia was closed or left open had an influence on vancomycin levels. The total vancomycin and tobramycin eluted into the drains was significantly less in the NPWT group with open fascia. The antibiotic levels measured in wound drainage remained above the minimum inhibitory concentration for common wound organisms throughout the study period. Neither NPWT nor fascial closure had a significant effect on tobramycin periosteal tissue concentrations.
Conclusions: Concurrent application of NPWT along with antibiotic-impregnated PMMA beads to simulated open femur fractures in pigs did not decrease local antibiotic concentrations in the wounds but did decrease the total amount of eluted vancomycin and tobramycin locally available when the fascia was left open.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.