Preliminary investigations on a new gentamicin and vancomycin-coated PMMA nail for the treatment of bone and intramedullary infections: An experimental study in the rabbit.

To evaluate a new gentamicin-vancomycin- impregnated (2:1) PMMA coating nail as a drug delivery device to treat bone and intramedullary infections, methicillin-resistant Staphylococcus aureus (MRSA) was used to induce femoral osteomyelitis in 20 New Zealand male rabbits. Four weeks after inoculum, the animals were submitted to debridement of infected femur canal, divided into four groups of five animals each and treated according to the following protocols: Group 1, insertion of a steel AISI316 intramedullary nail; Group 2, insertion of a gentamicin-vancomycin-impregnated PMMA nail; Group 3, no therapy; and Group 4 no fixation device and 1-week systemic antibiotic therapy with teicoplanin i.m. At 7 weeks after inoculum, the femurs were explanted sterilely. The radiological score showed that the lowest and best radiological score was observed in Group 2 that was significantly different from the other groups. The highest bacterial load in the femoral canal was found in Group 1, which was significantly different from Group 2 and Group 4 (p < 0.05). Histology showed that Group 2 produced a marked improvement (p < 0.005) of the bone injuries induced by the osteomyelitis in comparison with the other groups (Smeltzer score). The current findings showed that tested device might effectively lead to MRSA infection healing after surgical debridement and immediate implantation.