应力松弛接骨板固定对骨折愈合骨痂及板下骨改建的影响

Effect of stress-relaxation plate on forming callus and remodeling cortex structure beneath plate

目的 探讨应力松弛接骨板固定对骨折愈合骨痂及板下骨改建的影响。 方法 将 2 4只新西兰兔胫骨干横形截骨后 ,右侧用应力松弛接骨板 (stress -relaxationplate ,SRP)固定 ,左侧用坚硬接骨板 (rigidplate ,RP)固定并作为对照。所有动物分为 4组 ,每组 6只。术后 4～ 2 4周 ,偏光及透射电镜检查。 结果 早期两组间骨痂及板下骨结构改变相似 ,表现为骨痂胶原排列紊乱 ,折光性弱 ,板下骨吸收腔形成。 12周后 ,SRP组骨痂板层骨化 ,板下骨吸收腔逐渐变小 ;而RP组骨痂及板下骨吸收腔逐渐增多、增大 ,直至松质骨化。透射电镜发现 :(1) 4～ 8周时 ,两组间均出现活跃破骨细胞 ,SRP组骨表面同时可见较多功能活跃的成骨细胞 ,而RP组 ,成骨细胞功能不活跃。 (2 ) 2 4周时 ,SRP组愈合骨基质内骨细胞形态正常 ,破骨细胞少见 ;而RP组破骨细胞活跃 ,并见骨细胞性骨溶解现象。 结论 应力松弛接骨板固定促进骨痂后期改建 ,同时减少了板下皮质骨骨质疏松的发生 ,可望成为一种理想的接骨板。

Objective [WT5”BZ]To study the influence of stress relaxation plate (SRP) on forming callus and remodeling the cortex structure beneath the plate. [WT5”HZ]Methods [WT5”BZ]The bilateral tibia of New Zealand rabbits were osteotomized in the middle and fixed with SRP and rigid plate (RP), respectively. The callus forming and the cortex under the plate were studied with polarized light microscopy (PLM) and transmission electron microscopy (TEM) from 4 to 24 weeks postoperatively. [WT5”HZ]Results [WT5”BZ] Under PLM, the change of callus and cortex structure beneath the plate was similar between the SRP group and the RP group at the early stage of the operation, the collagen fibers in the callus were oriented in a disorderly pattern and had weak birefringence, and the resorption cavities could be seen in the cortex under the plate; at 12 weeks postoperatively, the callus in the SRP group started to transform to the lamellar bone, and the resorption cavities of the cortex under the plate became smaller. In comparison, the resorption cavities could be seen more and larger in the synthetic bone and the cortex, until the whole layer of the cortex was cancellated at 24 weeks after operation. Under TEM, active osteoclasts were observed in both the SRP group and the RP group during 4 to 8 weeks postoperatively; and in the SRP group, there also existed high functional osteoblasts, while in the RP group, the function of osteoblasts was not very active; the normal osteocytes were found at 24 weeks, and the osteoclasts were seldom found in the SRP group. On the contrary, the osteoclasts became more active and accompanied with the sign of osteocytic osteolysis. [WT5”HZ]Conclusions [WT5”BZ]The fixation with SRP not only enhances the callus forming, but also abates the degree of osteoporosis in the cortex under the plate. It suggests that SRP might be an ideal plate for bone fractures.