加压外固定促进合并放射损伤骨折愈合的实验研究

Experimental study on compressive external fixation for the management of fracture combined with irradiation bone injury

目的研究合并放射损伤的骨折难愈机制与促愈措施。方法60Coγ射线15Gy局部照射成年兔右后肢小腿,人工致胫骨横型骨折,以微型半环槽式外固定器加压固定骨折为加压组,未加压者为对照组,每组72只。分别于术后第1、3、6、12和24周通过组织学、X射线片、生物力学扭转试验、BMP,TGFβ1免疫组化染色、骨断端局部血流量测定及活体顺序性荧光标记新生骨等技术进行实验观察。结果加压组于术后12周断端已由骨性骨小梁完全连接;24周骨折断端骨性愈合,而对照组24周断端方由骨性骨小梁相连,但无血管及哈佛氏管形成。加压组于术后的各时相点骨断端处的局部血流量明显高于对照组(P<0.01);加压外固定能显著增加BMP、TGFβ1的表达;扭转试验测试,对照组12周骨折发生于原骨折处,其他各组均为骨干的螺旋型骨折,加压组12、24周抗扭强度及抗扭刚度均高于对照组(P<0.01,P<0.05):X射线片示加压组12周骨折线消失,24周骨质塑形,而对照组24周骨折线消失,但骨髓腔未通。加压组骨皮质的改建至术后24周已基本完成,而对照组尚未完成。结论加压外固定能加快骨复合损伤的修复速度并提高其愈合质量。

Objective To further explore the underlying mechanism of the compromise in healing capacity of bone after irradiation, and to seek means to promote healing capacity. Methods The model of fracture combined with radiation injury of bone （ combined injury of bone ） was established in rabbits by bisecting the upper third of the tibia with an electric saw, followed by fixation of fractured bone with a half-ring external flxator （improved llizarnv external fixator）. In the exprerimental group, compression was applied between two ends of the bone, and no compression was applied in the control group. The therapeutic effects of compressive external fixation on the combined injury of bone were observed with histological examination, roentgenograms, BMP-McAb and TGF-β 1-McAb immunohistochemistry, sequencing florescent labeling, measurement of local blood flow in the area of the fraeture at the 1^st 3^nd, 12^th , and 24^th week, and biomeehanie torstion test at the 12^th , 24^th week postoperatively. Results It was found that clinical bone healing was attained at the 12^th and bone construction was completed at the 24^th week after the operation in the experimental group, and in contrast, these processes were delayed for 6 weeks in the control group. Conclusion It is suggested that compressive external fixation can significantly accelerate the healing of combined injury of bone.