游离骨折块移位距离对骨折愈合影响的实验研究

Influence of fracture fragment displacement distance on fracture healing

目的 探讨长骨干粉碎性骨折游离骨折块移位距离对骨折愈合的影响. 方法 在120只新西兰大白兔右桡骨中部截取楔形骨块,制成实验模型,用2枚克氏针将骨块复位固定并使之与主骨存有一定的间距,并分为五组：A组（原位固定）、B组（骨块与骨干间距为桡骨干直径1/5）、C组（桡骨干直径2/5）、D组（桡骨干直径3/5）、E组（桡骨干直径4/5）.每组动物分别于术后2,4,6,8周分批处死,摄X线片观察各组骨折愈合情况,用改进Gary X线评分标准评分;取材HE染色,观察骨折愈合的组织形态学变化,免疫组化测定BMP-2的表达. 结果 （1）X线摄片显示：A、B组骨折愈合无差异,C、D组骨折愈合延迟,E组骨块吸收骨不连.（2）组织形态学观察：A、B组骨折局部形态学变化相同,而其他各组与A组相比,骨痂出现及改建的时间明显较晚,呈延迟愈合和不愈合的表现.（3）BMP-2表达：2周时BMP-2表达B组与A组差异无统计学意义（P＞0.05）,C、D、E组与A组比较差异有统计学意义（P＜0.01）,4周时只有E组与A组差异有统计学意义（P＜0.01）;6周和8周时各组之间差异无统计学意义（P＞0.05）. 结论游离骨折块移位距离会影响骨折的愈合,移位距离越大,对骨折愈合产生的影响越明显,当游离骨折块移位距离达到其骨干直径的2/5以上时,骨折将发生愈合障碍.

Objective To study the influence of the distance of displaced fragment on the union of diaphysis fracture. Methods A wedge-shaped bone fragment was taken from central radial of the right forelimb of 120 New Zealand white rabbits for estabhshment of experimental animal model. The bone fragment was fixed to the main bone with two Kirschner wires, with certain space between bone fragment and the main bone. Then, the rabbits were divided into five groups, ie, Group A （in situ fixation）,Group B （the space was 1/5 diameter of the radial shaft）, Group C （the space was 2/5 diameter of the radial shaft）, Group D （the space was 3/5 diameter of the radial shaft）, Group E （the space was 4/5 diameter of the radial shaft）. The animals were killed at 2, 4, 6, 8 weeks after operation. X-ray photos were taken to observe the fracture healing and the improved Gary X-ray used for scoring. HE staining after tissue section was employed to observe the histomorphological changes of fracture healing. Immunohistochemical method was used to determine expression of BMP-2. Results X-ray findings showed insignificant statistical difference between Group A and Group B, delayed union in Groups C and D and nonunion of bone absorption in Group E. Morphological observation showed same change in fracture site in Groups A and B lout significant late in emergence, formation and remodeling of the callus in the other groups compared with Group A, mainly with delayed fracture union or nonunion. There was no statistical difference in expression of BMP-2 between Group B and Group A （P 〉 0. 05）, but there was statistical significance in Groups C, D and E compared with Group A at 2 weeks （P 〈0.01）. There was statistical difference between Group E and Group A at 4 weeks （P 〈0. 01） but no statistical difference at 6 and 8 weeks between either two groups （P 〉 0. 05）. Conclusions The distance of displaced fragment will influence fracture healing. The larger distance of the displaced fragment will beget more obvious influence on fracture healing. When the distance is more than 2/5 diameter of the bone shaft, the fracture will present union disorder.