天鹅型记忆接骨器对骨折愈合影响的超微结构研究

目的：对比天鹅型记忆接骨器（SMC）与加压接骨折（CP）固定下骨折愈合的组织学和细胞超微结构变化，探讨SMC内固定下骨折愈合的特点。方法：25只家犬两侧股骨中段横型截骨，左侧以SMC内固定，右侧以CP固定，术后1、2、4、8、12周行X线摄片、光镜、电镜观察。结果：X线显示SMC组内固定后4周，骨折初步愈合，CP组在8周骨折愈合，SMC组愈合过程中未见明显的外骨痂及骨质疏松。骨折后2、4周时，SMC组骨痂内成骨细胞和成软骨细胞在数量上高于CP组，功能活跃。8周时SMC组骨折端已出现板样骨替代，CP组发生骨性连接，板下已出现骨吸收腔和退变相骨细胞。12周时SMC侧骨皮质出现部分吸收腔，CP组板下骨皮质吸腔更趋明显。结论：与CP相比，SMC内固定可使骨折端稳定的同时，又可对骨折断端施加主动的、持续的轴向应力刺激、有利于促进骨折愈合和骨改建。

Ultrastructural study on effects of swan-like memory compressive connector on bone healing

Objective:To explore the effect and mechanism of swan like memory compressive connector(SMC) made of Ni Ti shape memory alloy on experimental fracture healing. Methods:A transverse osteotomy on both sides of femoral diaphyses was performed in 25 adult dogs. One side was plated with compression plate(CP) and the other with SMC. Five animals in each group were sacrificed at 1,2,4,8,12 weeks after operation and observed with X ray examination, light microscopy and transmission electron microscopy. Results:In SMC group, the process of fracture healing was accelerated with SMC fixation, and no external callus and osteoporosis were observed. A great number of osteoblasts and chondroblasts with high functional activity emerged 2 4 weeks after operation. While in CP group, the number and functional activity of osteoblasts and chondroblasts were lower than those of SMC group. By 8 weeks after operation, the lamellar bone substituted the woven bone. The osseous callus bridged the fragments of fracture, but the bony absorbed cavities and osteocyte entered into degenerative phase were observed in cortical bone underneath CP. A small number of bony absorbed cavities were formed underneath SMC 12 weeks post operation, the bony absorption cavities underneath CP were enlarged remarkably. Conclusion:Fixation with SMC is stable, and it can provide continual axial stress for fracture fragment, which enhances fracture healing and bone reconstruction.