Establishment of prosthesis-related infection model after total knee arthroplasty in rabbits

Objective An animal model was developed to test the efficacy of innovative therapies for the prevention of biomaterial centered infections in knee caused by methicillin-resistant Staphylococcus anreus (MRSA) bacteria. Methods Prostheses of rabbit knees were successfully designed and consisted of two components: the femoral components were manufactured from Co-Cr-Mo alloy, and the tibial tray was made of high molecular weight polyethylene. They were implanted and fixed with bone cement in 48 tight knees of New Zealand White rabbits after proper anesthesia. After 4 weeks, the rabbits were randomly divided into 4 groups, including control group, experimental groups A, B and C. Each right knee was respectively inoculated with 0.5×10~3, 5×10~5, 5×10~7colony forming units (CFU) MRSA. The levels of serum C-reaction protein (CRP) and erythrocyte sedimentation rate (ESR) were monitored. Animals were sacrificed after 4 weeks. Joint aspirate, tissues, biomaterial and blood samples were examined for evidence of infection. Results None of the knees in the control group was infected after injection of 0.45% saline. Seven out of 12 knees developed a biomaterial centered infection in group A when 5×10~3 CFU MRSA were introduced. All knees developed a biomaterial centered infection in group B or group C when either 5.0×10~5 or 0.5×10~7 CFU MRSA were injected. No evidence of septicemia was found in the control group, group A and group B. But five blood cultures were positive in group C. The levels of serum CRP were ele-vated and reached the peak at the day 3, while ESR reached the peak at the day 7. Conclusion An ani-mal model of prosthesis-related infection in rabbits can be established successfully after 5×10~5 CFU MRSA are inoculated into the knees which were replaced 4 weeks ago. Key words: Arthroplasty; Methicillin-resistsnt staphylococcus aurous; Model,animal