背景:理想的骨折固定系统,在骨折早期应能达到坚强固定,后期要能防止应力遮挡作用诱发的固定骨段的骨质疏松.可降解骨科内固定材料无疑为此种骨折固定系统提供了理论可能.目的:旨在评估自制可变刚度接骨板系统(由可降解聚-DL-乳酸泡沫衬垫材料和钛合金接骨板组成)对兔胫骨干中段骨折的固定效果和对骨折愈合的影响.方法:新西兰大白兔64只采用随机数字表法分为实验组和对照组,线锯造成兔右侧胫骨中段骨折模型.用相对分子质量为 200 000的自制超高相对分子质量聚乳酸材料膜垫(厚1 mm)和4孔钛合金Tc4接骨板制作成可变刚度接骨板系统固定实验组兔胫骨中段骨折,以单纯Tc4钛合金接骨板固定对照组.于第2,4,8,12周处死动物,从大体观察、X射线平片、组织学和骨生物力学等方面观察和评定骨折愈合情况.结果与结论:X射线及大体标本示术后两组对位效果佳,无移位.组织学观察可见术后同期实验组标本较对照组标本骨痂内骨小梁排列紧密、髓腔开通完全、新生骨组织改塑重建完整.生物力学结果显示8周时两组愈合骨最大抗弯曲强度差异无显著性意义.12周时实验组愈合骨抗弯曲刚度优于对照组.提示自制可变刚度接骨板系统用于兔胫骨骨折固定效果可靠,有利于骨折段骨痂改塑重建,利于骨折愈合,用于骨折内固定治疗效果优于单纯钢板,为其进一步临床应用研究提供了实验依据.%BACKGROUND:An ideal fracture fixation system should strong fix bone fracture at early time and prevent stress shelter effect-induced local osteoporosis. Degradable internal fixation material provides theoretical basis fo r preparing this fixation system .OBJECTIVE:To investigate the result and effect of the changeable rigidity plate system composed of degradable poly-lactic-acid gasket and titanium alloy for the fixation of middle tibia fracture of rabbits.METHODS:Totally 64 New Zealand rabbits were divided into the experimental and control groups randomly. The tibia shaft fracture models were prepared by wire saw. The experimental groups were fixed with changeable rigidity plate systems which were made of self-restraint macromoleculer poly-lactic-acid gasket and 4-hole Tc4 plate. The control group was fixed with 4-hole Tc4 plate only. The bone fracture healing was evaluated by general observation, X-ray film, histological and biomechanic examination at 2, 4, 8 and 12 weeks after operation.RESULTS AND CONCLUSION:General observation and X-ray films showed that fracture contraposition and the bone healed well in both groups. The histological examination demonstrated that compared with the control group, osteotylus around the fracture was more thick and dense, marrow cavity cross earlier in the experimental group. The biomechanic examination found that there was no significant in maximum bending strength in two groups at 8 weeks, but the experimental group showed superior to the control group at 12 weeks. All these results prove that the complexity system with the changeable degrational gasket is a reliable method for the fixation of the tibia fractu re, which is benefit for the heeling of the bone than single plate. This experiment provides an experimental foundation for its further using in clinic.
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