二次损伤炎症启动犬萎缩性骨不连模型骨痂生长的组织病理学分析

Histopathological analysis of callus growth in canine atrophic nonunion model induced by secondary injury inflammation

目的探讨高能量骨折端邻近软组织二次损伤炎症刺激大量巨噬细胞募集对局部骨痂生长的启动作用。方法制备48个犬股骨高能量骨折模型,随机分为A、B组,各24只。A组立即行切开复位6孔钢板内固定术,术后2周再次行断端切开,进行单纯骨折端软组织剥离损伤。B组立即行切开复位6孔钢板内固定术。2组术后摄X线片观察骨痂生长情况。A组于二次损伤术后3 d、1周、2周、4周分别处死6只犬,B组于骨折后3 d、1周、2周、4周分别处死6只犬,取出骨折标本进行组织切片观察与透射电子显微镜观察。结果 A组二次损伤术后可见少量中性粒细胞浸润,随即募集大量巨噬细胞,间充质细胞亦同步趋化,启动旺盛的骨痂生长,产生骨痂愈合。B组骨折端邻近组织表现为大量中性粒细胞浸润,无巨噬细胞募集,无间充质细胞趋化,未发生骨折愈合级联反应,出现萎缩性骨不连。结论高能量骨折早期手术后邻近软组织巨噬细胞募集障碍可能是导致萎缩性骨不连发生的重要原因,而骨折端邻近组织炎症消退后的二次损伤炎症能够有效募集巨噬细胞,促进犬萎缩性骨不连模型的骨痂愈合。

Objective To clarify the priming effect of large numbers of macrophage recruitment in adjacent tissues on local osteophyte growth of high energy fractures. Methods Forty-eight canine femur high-energy fracture models were established and randomly divided into group A and B, 24 animals each group. Animals in group A immediately received open reduction and internal fixation of the steel plate, and two weeks after surgery the fracture sites were cut again, and a simple fracture end peeling injury was made. Animals in group B immediately received open reduction and internal fixation of the steel plate. Xrays were taken to observe the growth of the bone. Six dogs in group A were sacrificed at 3 d, 1 week, 2 weeks and 4 weeks after the second injury surgery, and 6 dogs in group B were sacrificed at 3 d, 1 week, 2 weeks and 4 weeks after fracture. And the sections of fracture specimens were prepared for histological analysis and transmission microscope observation. Results A small amount of neutrophil infiltration was observed after the second injury in group A, which lead to the recruitment of numerous macrophages. Mesenchymal cells chemotaxis and growth of osteophytes were initiated, which resulted in the osteophyte healing. The adjacent tissues of bone fracture in group B showed infiltration of numerous neutrophils. No macrophage recruitment, no mesenchymal cell chemotaxis, and no fracture healing cascade were observed, which finally caused atrophic nonunion. Conclusion The failure of macrophage recruitment of soft tissue near to the bone fracture in high-energy fracture model may cause atrophic nonunion. The secondary injury after the tissue inflammation subsides can effectively recruit macrophages and promote the healing of the epiphysis of the nonunion model.