Objective To observe the effects of seawater immersion on the healing process of open tibial fracture in rabbits.Methods Forty-four New Zealand rabbits were randomly divided into two groups: the experimental group (group A) and the control group (group B), each consisting of 22 animals. The 2 groups of animals all had bilateral open fracture of tibia. The wounded limbs of the animals in group A were immersed in the artificial seawater for 3 hours. And the animals in group B were left there untended for 3 hours. Following debridement, wounds were sutured. Lesion of osteoblast, vascular endothelial growth factor (VEGF),the expression of transforming growth factor-β1 (TGF-β1) and the process of porosis in the animals of both groups were observed on the 7th,14th,21st and 28th days respectively under the electron and optical microscopes.Results (1) Under the electron microscope, obvious lesion of osteoblast in the animals of group A was observed at the fractured sites, 7-14 days after the fracture, displaying cell membrane and nuclear membrane damage, mitochondrial swelling and vacuolation, cell nucleus dissolution and necrosis. On the 21st and 28th days, morphology of osteoblasts in the animals of group A returned to normal. (2) Immunohistochemistry indicated that the expression of VEGF and TGF-β1 in the animals of group A increased and gradually rose to the peak on the 14th day after fracture, and then decreased. The expression of VEGF and TGF-β1 was not delayed in the animals of group A, but their expression intensity at various times was all obviously weaker than that of group B.(3)On the 28th day, for the animal in group B, 15 limbs were of complete osseous callus, accounting for 75%, while 5 limbs were of mixed type osseous callus, accounting for 25%. For the animal in group A, 6 limbs were of complete osseous callus, accounting for 30%, while 14 limbs were of mixed type osseous callus, accounting for 70%. Significant statistical differences could be seen, when a comparison was made between the groups(P<0.01).Conclusions The process of intramembranous/cartilaginous ossification and fracture healing delayed, following open fracture of limbs coupled with 3-hour seawater immersion.%目的 观察海水浸泡对兔胫骨开放性骨折愈合进程的影响.方法 44只新西兰兔按数字表法随机分为实验组和对照组,每组22只,均造成双侧胫骨横行骨折.实验组伤口浸泡于人工海水中3 h,对照组旷置3 h,清创后依次缝合伤口.电镜和光镜下观察2组第7、14、21、28天成骨细胞损伤情况、组织中血管内皮生长因子(VEGF)、转移生长因子-β1(TGF-β1)的表达及骨痂形成过程.结果 (1)电镜下,实验组骨折处成骨细胞在骨折后第7～14天可见明显损害,表现为胞膜及核膜破坏、线粒体肿胀空泡变、胞核溶解坏死,第21天及第28天成骨细胞形态恢复正常.(2)免疫组化显示,对照组VEGF及TGF-β1的表达于骨折后逐渐增强,至第14天时达到高峰,之后呈减弱趋势;实验组表达未见延迟,但各时段表达强度均明显弱于对照组.(3)第28天时,对照组骨痂完全为骨性骨痂者共15肢,占75%;为混合性骨痂(即软骨骨痂与骨性骨痂共存)者共5肢,占25%.实验组骨痂完全为骨性骨痂者共6肢,占30%;为混合性骨痂者共14肢,占70%.2组比较差异有统计学意义(χ2=8.12,P<0.01).结论 肢体开放性骨折经海水浸泡3 h后,膜内成骨及软骨内成骨进程延缓,骨折愈合延迟.
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