SD大鼠股骨慢性骨髓炎模型构建与评价

Construction and evaluation of an animal model of chronic osteomyelitis of femur in SD rats

目的建立并评价SD大鼠股骨慢性骨髓炎动物模型。方法取雄性SD大鼠24只,暴露大鼠右股骨髁间沟,用电钻于股骨髁间沟处钻1个直径0.5 mm的小孔直通股骨髓腔,向髓腔内注入50μL细菌密度为1×10^(6)/mL的金黄色葡萄球菌悬液,用无菌骨蜡密封孔洞。观察大鼠术后行为学、切口愈合、体温、病灶大体感染等情况;术后2、4、8周,取大鼠造模股骨周围软组织进行细菌培养,采用小动物CT机观察股骨影像学表现;术后2、8周,取造模股骨组织制成病理学切片,进行H-E染色、吉姆萨染色及Masson染色。结果造模后大鼠右后肢勾悬、不能负重,术后第10天左右手术切口完全愈合,第12天恢复至正常活动水平,第15天以后活动水平稍有下降。术后大鼠体温逐渐升高,感染部位局部红肿;2周以后体温虽下降,但仍然高于正常体温,部分大鼠右膝关节局部出现包块;4周后所有大鼠均有局部红肿和体温升高等症状。大鼠造模股骨周围软组织细菌培养可见均匀分布的金黄色葡萄球菌菌落,且随时间延长而增多。小动物CT机检查结果显示,术后8周大鼠造模股骨髓腔内炎症反应明显,骨质破环累及骨皮质全层,死骨形成并伴有新骨生成。造模股骨组织病理学分析结果显示,术后2周骨髓腔内有大量炎症细胞浸润,炎症局限于骨髓腔内,可见皮质骨中胶原纤维连续排列,组织内含有大量的金黄色葡萄球菌;术后8周炎症迁延,皮质骨中胶原纤维大量断裂,皮质骨大量破坏且有窦道与外界相连,组织内金黄色葡萄球菌数量进一步增多。结论SD大鼠股骨慢性骨髓炎模型造模成功,可较好地模拟临床骨髓炎病理生理变化,具有高度可复制性。

Objective To establish and evaluate an animal model of chronic osteomyelitis of femur in SD rats.Methods Twenty-four male SD rats were used to construct the osteomyelitis model.The intercondylar groove of the femur was exposed in rats,and a small hole with diameter of 0.5 mm was drilled by electric drill into the intercondylar groove of femur through the femoral bone marrow cavity.Staphylococcus aureus suspension of 50μL with concentration of 1×10^(6)/mL was injected into the right femoral bone marrow cavity of rats,and then the hole was sealed with sterile bone wax.The behavior,wound healing,body temperature,healing of the incision,and gross infection of the lesion were observed after operation.At 2,4 and 8 weeks after operation,the soft tissue around the femur of rats was taken for bacterial culture,and micro-CT findings of the molded femur were observed.Histopathological sections were analyzed by hematoxylin-eosin,Giemsa and Masson staining at 2 and 8 weeks after surgery.Results The right lower limb of the osteomyelitis rats was suspended without weight bearing after operation,and the surgical incision completely healed about 10 d later.The animal returned to normal activity level on day 12,and 15 d after surgery the activity level decreased slightly.The body temperature of the rats began to rise after operation,and local redness and swelling occurred.After 2 weeks,the body temperature gradually decreased,but still higher than normal.The local swelling of right knee joint appeared in some rats.After 4 weeks,local swelling and body temperature increased in all the osteomyelitis rats.Staphylococcus aureus colonies were evenly distributed in the soft tissue culture around the femur of rats,and increased with time.Micro-CT results showed that 8 weeks after operation,inflammation reaction was obvious in medullary cavity of rats,with bone fragmentation involving all layers of bone cortex,also with dead bone formation and new bone formation.The histopathological analysis of the femur showed many inflammatory cells infiltrating into the bone marrow cavity with inflammation limited to the bone marrow cavity 2 weeks after operation,the collagen fibers in the cortical bone were arranged continuously,and a large number of Staphylococcus aureus were contained in the tissue.Eight weeks after operation,inflammation persisted,the collagen fibers in the cortical bone were broken and the cortical bone was destroyed,sinus channels were connected with the outside in cortical bone,and the number of Staphylococcus aureus in the tissue increased.Conclusion A model of chronic osteomyelitis of femur has been successfully established in SD rats,which can simulate the pathophysiological change of clinical osteomyelitis and has high replicability.