天鹅型记忆接骨器对大白兔骨折愈合骨矿含量及力学性能的影响

目的　探讨天鹅记忆接骨器 (SMC)对实验性骨折愈合的骨矿含量和力学性能的影响 ,揭示其促进骨折愈合的机制。方法　 40只新西兰大白兔双侧肱骨干截骨后 ,随机选取一侧用天鹅型形状记忆接骨器固定 (SMC组 ) ,对侧用 4孔加压接骨板 (DCP)固定 (DCP组 ) ,分别在术后 2、4、8、12、16周时杀死取材 ,行骨折部骨矿密度测量和抗拉伸力学性能测试 ,观察固定段骨矿含量和力学性能变化。结果　术后 4周开始 ,SMC组骨矿含量开始高于DCP组 (P <0 0 1) ,至术后 16周时 ,两组含量接近。在同一时间段内 ,SMC组的抗拉伸刚度明显优于DCP组 (P <0 0 5或P <0 0 1)。DCP组术后 12周以后 ,其力学性能即不再增加。结论　SMC与DCP相比 ,具有材料特性和几何构型上的优势 ,有助于骨折愈合过程中骨矿物质的沉积 ,防止固定段骨骨质疏松发生 ,使骨的力学性能尽早恢复

Effects of swan-shaped memory connector on bone mineral density and mechanical properties of humeral fracture in rabbits

Objective To investigate the effects of swan shaped memory connector(SMC) on the bone mineral density and mechanical properties of humeral fracture in rabbits in order to disclose the mechanism of SMC stimulating fracture healing. Methods Shafts of both humeri of 40 rabbits were osteotomized. One side was selected to fix with SMC, but the contralateral side was fixed with the 4 hole dynamic compression plate (DCP). Eight rabbits were sacrificed and the humeri were harvested respectively at 2, 4, 8, 12 and 16 weeks after operation. The bone mineral density(BMD) was examined by dual energy radiographic absorptiometry(DRA). The mechanical properties were assessed by mechanical traction test. Results From 4 to 16 weeks after operation, the BMD in SMC group was significantly higher than that in DCP group ( P <0 01 or P <0 01). Simultaneously, the traction strength in SMC group was also stronger than that in DCP group( P <0 05 or P <0 01). However, at 12 weeks after operation, the mechanical properties in DCP group stopped improving. Conclusion The advantageous material and geometrical conformation in SMC group are beneficial to bone mineral deposition and early recovery of the mechanical properties of the fixed bone.