含药髓内钉缓释系统对兔胫骨骨折后骨髓炎的预防研究

Preventive effect of drug delivery system in intramedullary nail on osteomyelitis after fracture in tibia of rabbit

目的探讨含药髓内钉缓释系统用于开放污染性骨折一期固定对预防术后感染及促进骨损伤修复的效果。方法在自行研制的兔胫骨用不锈钢质交锁C形套管中,分别灌注聚甲基丙烯酸甲酯(PMMA)、加有庆大霉素的PMMA、含骨形态发生蛋白-2(BMP-2)人工骨粒和庆大霉素PMMA的混合物,制备成空白、庆大霉素和复合材料三种套管。采用兔胫骨污染性骨折模型,于胫骨近端骨窗内注入金葡菌后即刻,分别置入复合材料套管(复合材料组)、庆大霉素套管(庆大霉素组)和空白套管(空白组)。术后3个月无菌取材,进行解剖学、放射学、组织学、细菌学检查,比较上述三组骨感染预防和促进成骨作用。结果术后3个月,复合材料组的细菌计数及改良的Norden分值较庆大霉素组及空白组明显减少(P均<0.01);复合材料组和庆大霉素组在其解剖学及组织学观察的骨髓炎程度也明显好于空白组。术后3个月,复合材料组和庆大霉素组改良的X线Norden骨髓炎分值均极低,明显小于空白组(P<0.01),其解剖学和组织学观察均无骨髓炎表现,复合材料组的髓腔再通情况明显好于庆大霉素组。结论含BMP-2异体骨粒和庆大霉素PMMA混合物的交锁髓内钉缓释系统除有非常强的抗感染能力外,还有良好的骨传导和骨诱导作用,能应用于开放污染性骨折的一期固定,并能有效预防骨髓炎的发生。

Objective To study the effect on the prevention of osteomyelitis by drug delivery system in intramedullary nail as onestage internal fixation in rabbits. Methods A rabbit tibial osteomyelitis model was used, in which staphylococci aureus was injected through a bone fracture, followed by immediate internal fixation with stainless steel C-shape case as intramedullary nail which included polymethyl methaerylate （PMMA） with slowly-delivered gentamicin and artificial bone with bone morphogenetic protein-2 （BMP-2） in Group A, PMMA with slowly-delivered gcntamicin in Croup B, and PMMA in Group C. Specimens were harvested 3 months postoperatively for gross observation, and radiological, histological and bacteriological evaluation. Comparison was made among the three groups with regard to the beneficial effect of the above procedures on preventing osteomyelitis. Results At 3 months, the values of bacteria counting and modified Norden scoring in Group A were the smallest among all the three groups （ P 〈0. 01 ）. The recanalization of medullary cavity and the radiologically modified Norden scoring were better in Croup A and B than in Group C （P 〈 0.01 ）. Conclusion Apart from its slowly delivering antibiotics, the delivery system including PMMA with gentamicins and artificial bone with BMP-2 in intramedullary nail is capable of taking osteoconductive and osteoiuductive effect, so it could be used in primary internal fixation to repair a contaminated fracture for effective prevention of osteomyelitis.