自控微动带锁髓内钉内固定促进骨折愈合的扫描电镜观察

目的观察采用自控微动带锁髓内钉（autocontrol micromotion locking nail，AMLN）固定对骨折愈合的影响及机制。方法对14只山羊两侧股骨干横断截骨，分别采用AMLN和GK钉内固定，术后1、2、4、8周分批处死，采用扫描电镜观察骨折愈合过程中细胞的超微结构变化。结果术后1～2周AMLN固定组骨痂丰富、排列有序，骨小梁的吸收陷窝内有胶原纤维不断形成；术后4～8周骨胶原纤维在吸收陷窝内外形成丰富，互相平行束状排列，与骨干主应力轴相一致，骨吸收和骨形成活跃，骨塑形改建迅速，哈佛氏系统结构完整，结构网架在骨质钙盐结晶沉积下十分坚韧；而GK钉固定组则无上述特征现象发生。结论AMLN钉固定使骨折端局部稳定、有轴向生理性应力刺激与应力传导，增加了成骨细胞的代谢活性，使骨小梁沿压应力轴线发育，骨折边愈合边塑形，给骨折愈合提供了较佳的力学环境。

Scanning Electron Microscopy for Influence of Autocontrol Micromotion Locking Nail Internal Fixation on Fracture Healing

Objective To explore the influence of autocontrol micromotion locking nail (AMLN) fixation on the fracture healing and the mechanism.Methods Twenty-eight femoral shafts of fourteen sheep were fractured transversely and were fixed with AMLN or GK nails respectively. The sheep were killed respectively at the first,the second,the fourth and the eighth week postoperatively.The changes of the ultrastructure of cells in the process of fracture healing were observed with the scanning electron microscope.Results In one week or two weeks after operation,the callus in the AMLN fixing group was rich and in order;there was continuous formation of the collagen fibers in the absorption lacuna of the bone trabecula.From the fourth week to the eighth week after operation,the collagen fibers in the absorption lacuna of the bone trabecula were rich and paralleled the principal axis of stress of the bone shaft;both bone absorption and bone formation were active;the bone reconstruction was rapid;the Havasian system was integral;the structural network of the bone was very strong with the crystal deposition of the calcium salts.However,no phenomena mentioned above were observed in the GK fixation group. Conclusion The AMLN fixation with the axial physiological stress stimuli and the stress conduction can stabilize the fracture,increase the metabolic activity of the osteobalsts and make the trabecular bone grow along the axis of the tress,which will make the bone healed and molded in the same time.The AMLN fixation provides a better topical biomechanical environment for fracture healing.