兔膝关节置换术后感染模型的建立

目的 建立兔膝关节置换(TKA)术后感染模型.方法 设计制作兔膝关节假体,新西兰兔48只行右膝TKA,4周后随机分为4组:对照组膝关节腔内接种无菌0.45%NaCl溶液,实验A、B、C组分别接种5×10~3、5×10~5、5×10~7CFU耐甲氧西林金葡菌(MRSA);监测血沉(ESR)、C-反应蛋白(CRP),4周后处死,取材行细菌培养和血培养.结果 感染率:对照组0(0/12);实验A组58.3%(7/12);B组100.0%(12/12);C组100.0%(12/12).血培养阳性率:对照组0(0/12);实验A组0(0/12);B组0(0/12);C组41.7%(5/12).实验组CRP、ESR显著升高,分别于第3、7天达峰值并维持在较高水平.结论 兔TKA术后4周接种5×10~5CFU的MRSA可成功建模.

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.