BACKGROUND: To establish an animal osteomyelitis model is the basis and key to explore the treatment of osteomyelitis. In the past, direct addition of bacteria was used to make the osteomyelitis model, which is significantly different from clinical pathogenic factors. Moreover, it is difficult to control the amount of bacterial suspension dripped, which can easily lead to the death of model animals. Osteomyelitis caused by bacterial biofilms is the most common in clinical practice. 
OBJECTIVE: To prepare a rat model of osteomyelitis by inserting Kirschner wires with bacterial biofilms into the rat bone marrow cavity.
METHOD: Bacterium-bearing Kirschner wires were prepared using Staphylococcus aureus. Eighteen healthy Sprague-Dawley rats were enrolled. Kirschner wires with Staphylococcus aureus biofilms were inserted into the rat tibia, and the borehole was sealed with sterile paraffin. Rats’ behaviors and incision healing were observed after modeling. Bone infection was observed through imaging and pathological examinations at 4 weeks after modeling. Secretions at the model site were aseptically taken for bacterial culture, and mass spectrometry was used to identify whether they were the bacteria inoculated during the production of bacterial biofilms, and the serum inflammatory factors of rats before and after modeling were detected as indicators for evaluating the success of the osteomyelitis model.
RESULTS AND CONCLUSION: All the 18 rats presented with the characteristics of osteomyelitis. They all showed different degrees of pus, dead bone, dead space and new bone formation. After modeling, the levels of serum inflammatory factors, such as procalcitonin, tumor necrosis factor alpha and interleukin-10, increased significantly (P < 0.05). The bacteria that formed after secretion culture were identified as Staphylococcus aureus. To conclude, the rat osteomyelitis model can be successfully made by inserting the Kirschner wire into the rat tibia through the Staphylococcus aureus biofilm, which is closer to osteomyelitis in clinic.