Establishment of an animal model of chronic osteomyelitis with Staphylococcus aureus by ligating the femoral artery of rats

Background Osteomyelitis caused by Staphylococcus aureus (S. aureus) is an important post-operation complication, especially after fracture internal fixation and artificial joint replacement. Animal models play an indispensable role in exploring the pathogenesis of osteomyelitis. Most models use internal fixation, bacterial suspension and vascular sclerosing agent to destroy blood vessels. Vascular sclerosing agents not only damage blood vessels but also lead to local inflammatory immune disorders, which is different from simple vascular disease and osteomyelitis caused by ischemia in clinical practice. Methods The experimental animals were randomly divided into three groups: femoral artery ligation group, vascular sclerosing agent group and non-infection aseptic operation group. In the femoral artery ligation group, the femoral artery was ligated to reduce the blood flow of the affected limb to simulate the clinical ischemic state and increase the susceptibility, then the Kirschner needle with S. aureus biofilm was implanted into the tibia of rats, and the bone defect was sealed with aseptic paraffin. The non-infection aseptic operation group and the infection model group caused by vascular sclerosing agent have been used as the blank and positive control group. After operation, survival rate, body temperature and incision healing were monitored. Four weeks later, radiological and pathological changes of all animals were evaluated, and the secretions from osteomyelitis experienced etiological separation and cultivation. Results The chronic osteomyelitis model was established successfully by ligating femoral artery and implanting Kirschner needle covered with S. aureus biofilm. Signs of chronic osteomyelitis were observed in all rats of femoral artery ligation infection group and positive control group. No signs of infection and chronic osteomyelitis were found in the non-infection aseptic operation control group. Conclusion The method of ligating the femoral artery and implanting Kirschner needle with S. aureus biofilm into the tibia of rats can effectively establish a stable and reproducible chronic osteomyelitis model which is closer to the clinical pathogenesis and natural route of infection. This model could be useful for the study of pathogenesis and therapeutics of chronic osteomyelitis with S. aureus.