小夹板固定对实验性家兔长管状骨骨折愈合骨密度的影响

目的：通过测定小夹板局部外固定骨折愈合过程中骨密度值及比率,探讨小夹板固定对骨折愈合的影响和机制。方法：将18只家兔通过手术造成左侧胫骨中下1/3 3 mm标准横形骨折模型,随机分成A组、B组、C组,每组各6只。A组与B组用石膏固定5 d后改成小夹板外固定,但A组与B组夹板包扎松紧不一致,A组包扎带上下移动3 mm,B组移动7 mm,C组钢板内固定;术后第6周末处死家兔进行骨密度及比率测定,每只家兔在处死前先行X线摄片检查。结果：X线摄片显示A组骨断端致密骨痂填充,骨折线模糊,外骨痂致密,部分髓腔再通,而B组和C组骨折端骨痂较少,骨折线仍存在。骨密度值测量显示,A组与B、C组比较,有非常显著性差异（P〈0.01）。结论：微动加速了局部矿物化,增加骨膜骨痂的成骨,是加速骨折愈合的最重要机制。

Influence of Small Splint Fixation on Bone Density in Experimental Rabbits of Long Tubular Bone Fracture Healing

Objective：To explore the influence and mechanism of external fixation of small splint on fracture healing by determining bone density value and ratio during fracture healing. Methods：Typical 3mm transverse fracture model was prepared at middle-inferior 1/3 of left tibia in 18 rabbits. A,B and C groups were randomized,6 rabbits in each one. In groups A and B, after gypsum fixation for 5 d, small splint fixation was applied, but the tightness of splinting was different between groups A and B. In group A,the ribbon was shifted up and down by 3 mm and in group B by 7 ram. In group C, steel plant was used for fixation. At the end of the 6th week after operation,the rabbits were sacrificed for the determination of bone density and ratio. X-ray test was done before sacrificed. Results ：X-ray showed that in group A, the fractured ends of bone were filled up by compact callus,the fracture line was vague, external callus was compact,recanalization could be found in partial medullary cavity,while in groups B and C,there was less callus in fractured ends and the frac- ture line was still existed. The measure of bone density and ratio demonstrated that there was highly significant difference in comparison of group A with groups B and C（P〈0.01 ）. Conclusion ：Micromotion accelerates the local mineralization,enhances bone formation of periosteal callus, which is the most important mechanism for the acceleration of fracture healing.