Comparison of Gentamicin Impregnated Polymethlymetacrylate Bead, Gentamicin Coated Native Calcium Sulfate Bead and Gentamicin Coated High Porous Calcium Sulfate Bead on Osteomyelitis Management in a Rat Model

Three types of gentamicin beads were compared in a rat osteomyelitis model. The gentamicin beads were prepared in cylinder shape (diameter 2 mm x height 4 mm). Gentamicin impregnated polymethylmethacrylate (GIPMMA) beads were fabricated according to manufacturer’s instructions. Gentamicin coated native calcium sulfate (GNCS) bead and gentamicin coated high porous calcium sulfate (G-HPCS) bead were prepared in laboratory. Osteomyelitis was induced in the rat’s tibias by using methicillin resistance Staphylococcus aureus (MRSA). After 3 weeks of infection, the infected tibias were implanted with GI-PMMA bead, G-NCS bead, G-HPCS bead or sham treatment (control). Radiographic change, white blood cell count and infection signs were weekly monitored for 6 weeks. At the end of the experiment, all tibias were collected for histopathologic examination and bone culture. Although white blood cell count and infection signs were not significantly different among different group of rats, the radiolucent area reduced significantly in GI-PMMA, G-NCS and G-HPCS compared to the control group. There was no significant difference in bacterial count among the groups, however, the histopathologic results revealed new bone development in G-NCS and G-HPCS groups, and a large bone defect in GI-PMMA group resulting from bead removal. This study suggests that the G-HPCS can be used as a local antibiotic carrier for management of osteomyelitis instead of calcium sulfate and polymethylmethacrylate beads.