应力松驰接骨板对骨结构的影响

Effects of Stress-Relaxation Plate on the Disorganization and Reparation of Regional Bone Structure

目的探讨应力松驰接骨板对局部皮质骨结构紊乱和修复的影响。 方法在传统坚硬接骨板 (RP)螺孔内加一具有蠕变性能的聚乙烯垫圈 ,构成应力松弛接骨板 (SRP) ,对 48只兔胫骨干截骨后 ,分别以SRP和RP固定 ,术后 2～ 36周 ,采用偏光镜、胶原mRNA原位杂交及免疫组化技术对两种接骨板固定板下骨质疏松的发生 ,以及对修复过程中Ⅰ、Ⅲ型胶原mRNA表达和蛋白合成作比较。 结果 12周前板下骨结构紊乱相仿 ,但SRP组骨结构紊乱发生较迟 ,程度轻 ,12周开始出现修复 ;8～ 12周 ,SRP组吸收腔表面可见成骨细胞表达Ⅰ型胶原mRNA和分泌Ⅰ型胶原蛋白 ;12～ 2 4周 ,上述变化逐渐增加 ;至 36周 ,吸收腔基本修复。RP组各期胶原基因表达和合成均少见。结论应力松弛接骨板可减轻板下骨骨质疏松的发生 ,通过吸收腔表面成骨细胞高效表达和合成Ⅰ型胶原 ,使疏松骨结构得到修复。

Objective To study the influence of stress-relaxation plate on disorganization and repair of the cortex under the plate. Methods A washer made of viscoelastic polyethylene was placed between the screw and the screw hole of a conventional stainless rigid plate(RP) to form a stress-relaxation plate(SRP). Both SRP and RP were applied to the osteotomized New Zealand rabbit tibia, the fracture healing process of either fixing with SRP or RP(control) was put under comparative study by polarized light microscopy, in situ hybridization of collagen mRNA and immunohistochemistry technique from 2 to 36 weeks postoperatively. Results The study of plated bone remodeling showed that the degree of cortex osteoporosis beneath the plate was similar between the SRP and RP group 12-week postoperatively. The organization of the bone structure in the SRP group happened later and milder than that of the RP group, and the repair process began 12 weeks after implantation. So the resorption cavities became smaller and the structure of collagen fibers became well oriented along, and the osteoblasts lying on the surface of resorption cavities expressed and synthesized type Ⅰ collagen 8 to 12 weeks after implantation. The changes above increased significantly in most cavities by 36 weeks. No expression and synthesis of any kind of collagen could be observed during 12 to 36 weeks after implantation in the RP group. Conclusion Without removal of the bone plate, the SRP fixation not only reduces the degree of plated bone osteoporosis, but also makes the disorganized bone structure return to normal by the expression and synthesis of type Ⅰ collagen mRNA of osteoblasts lying on the surface of resorption cavities.