复合庆大霉素抗生素骨制备及其治疗感染性骨缺损的实验研究

PREPARATION OF GENTAMICIN-IMPREGNATED BONE ALLOGRAFT AND EXPERIMENTAL STUDY ON TREATMENT OF INFECTIVE BONE DEFECT

目的研制一种既有成骨作用，又有抗感染能力，且免疫原性较低的新型植骨材料。方法以5mm×5mm×5mm骨粒和6mm×6mm×20mm骨条作为载体，采用超声和负压双重复合法制备复合庆大霉素抗生素骨粒和骨条。将抗生素骨粒分别埋入24只Wistar大鼠左、右股肌袋内，于术后1、3、5、7、10和14d检测庆大霉素体内释药浓度及持续时间。将健康雄性成年绵羊10只，制成6mm×6mm×20mm左前肱骨和右后股骨缺损感染模型，于缺损处注入5×10^10 CFU／ml金黄色葡萄球菌1ml。将感染动物随机均分为实验组和对照组（n=5），实验组将复合庆大霉素抗生素骨条植入缺损区，对照组将空白骨条植入缺损区。术后行大体观察、白细胞计数、X线片及组织学观察。结果大鼠抗生素骨粒植入后1d，骨粒与肌肉组织中药物浓度分别为46．1μg／ml和17．3μg／ml，后缓慢释放，至14d局部软组织药物浓度仍高于金黄色葡萄球菌最小抑菌浓度（〈2．0μg／ml）。羊体内抗感染实验：术后2周，实验组1只羊1侧肢体植骨部位出现脓性分泌物，4～8周植入骨与周围较好融合，12周愈合良好；对照组2～8周植入骨基本被脓液包裹或软组织取代，其中1只羊于20d死亡，12周植骨区除中央被软组织填充外，余愈合较好。白细胞计数术前各组均在正常生理范围，术后1～14d实验组白细胞计数均低于对照组。X线片和组织学观察显示，实验组术后2周除1侧肢体植骨腔内出现脓液，余在各周内逐渐有新骨生成并爬行取代植入骨，愈合良好；对照组2～8周显示植入骨被脓液包裹，并逐渐被吸收，未见新生骨爬行取代。结论复合庆大霉素抗生素骨具有较好的缓释特性、体内抗感染效果和成骨能力，有望成为治疗感染性骨缺损的一种较理想的骨植入材料。

Objective To study and prepare a new kind of bone graft, which has osteogenesis, local antiinfective function and low immunogenicity. Methods Gentamicin-impregnated bone was prepared by means of ultrasonic and vacuum, the release of gentamicin in vivo was measured by inhibition bacteria. Ten healthy male adult sheep were made animal infection models of thigh bone or humerus defect of 6 mm × 6 mm × 20 mm at size, and the defect was inoculated into 1 ml 5× 10^10CFU/ml Staphylococcus aureus. The animals were randomly divided into the experimental group （n=5, the bone graft with gentamicin was implanted） and the control group （n=5, the bone graft without gentamincin）. Macroscopic, WBC count, radiological, and histological investigations were carried out to evaluate the anti-infective and osteosis capability. Results The concentrations of gentamicin were 46. 1 μg/ml in bone allograft and 17. 3 μg/ml in muscles after 1 day. The concentrations of gentamicin exceeding the minimum inhibitory concentration lasted for 14 days in vivo. WBC in the control group was higher than that in the experimental group. In the control group, 1 case died owing to septemia 3 weeks after operation. The implanted bones were wrapped in pus 4 and 6 weeks, and the defects were filled with fibre tissue 8 and 10 weeks after operation. In the experimental group, 1 case was infected, the others had a good concrescence. The bone allografts began to integrate with adjacent bone after 4- 8 weeks and integrate well after 12 weeks. The X-ray and histological observation showed that new bone formed and took the place of bone allograft. Conclusion The gentamicin-impregnated bone allograft was of a good sustained release feature in vivo, local anti infection and osteogenesis. It might be an ideal bone grafting material for bone defects with infection.