摘要
目的测量三足负重酒精灭活性股骨头坏死犬模型的股骨头松质骨的矿物质密度和骨小梁的三维结构变化,初步探讨局部注射酒精和负重对股骨头力学强度的影响。方法取健康成年Beagle犬24只,体重18～23 kg。随机取12只犬建立三足负重犬动物模型,余12只不作任何处理,为四足犬。所有动物随机取一侧后肢为实验侧,于股骨头内局部注射无水酒精,建立股骨头坏死犬动物模型;对侧为对照侧,股骨头内注入等量生理盐水。将三足和四足犬对照侧作为对照组,三足犬实验侧为三足犬组,四足犬实验侧作为四足犬组。于髋部注射酒精后1、3、6及12周处死动物,取双后肢股骨头行Micro-CT扫描。以股骨头内钻孔针道为中心,自针道边缘由中心向外各选取相互连接的直径为1 mm的圆柱形区域,依次命名为Ⅰ、Ⅱ和Ⅲ区。对各区的骨矿密度(bone mineral density,BMD)、骨体积分数(bone volume fraction,BVF)、骨矿容量(bone mineral content,BMC)、骨表面积与骨骼体积比(bone surface to bone volume ratio,BS/BV)、结构模型指数(structure model index,SMI)、骨小梁厚度(trabecular plate thickness,Tb.Th)、骨小梁数目(trabecular plate number,Tb.N)、骨小梁间隙(trabecular spacing,Tb.Sp)进行测量和比较;对股骨头软骨下骨区行三维重建,观察其三维结构变化。结果注射酒精后1周各组各项参数差异均无统计学意义(P > 0.05)。3周,三足犬和四足犬组Ⅰ、Ⅱ和Ⅲ区的BMC、BMD、BVF及BS/BV自针道向外逐渐递增,各区间差异有统计学意义(P< 0.05)。6周,三足犬组和四足犬组Ⅰ、Ⅱ区的BMC、BMD、BVF和Tb.N较Ⅲ区明显下降,Tb.Sp较Ⅲ区增加,差异有统计学意义(P< 0.05)。12周,对照组、三足犬组和四足犬组3区的各项参数差异无统计学意义(P> 0.05)。注射酒精后3周,BMC、BMD和BVF在三足犬组和四足犬组开始下降,与1周比较差异有统计学意义(P< 0.05);6周,下降最明显,BMC与1、3周比较,差异有统计学意义(P< 0.05),BMD与BVF差异无统计学意义(P> 0.05),12周与6周比较,差异无统计学意义(P> 0.05)。三足犬组股骨头内注射酒精后,随时间延长,骨小梁结构逐渐变细、密度降低、间隙增宽、12周时可观察到局部骨小梁的连续性破坏和骨小梁的断裂。结论局部注射酒精致犬股骨头坏死后,坏死骨质的吸收将导致骨小梁力学强度的下降。持续的生物应力将阻碍坏死后的修复反应,使坏死骨小梁的力学强度更为降低,是致坏死股骨头塌陷的重要原因。
Objective To measure the changes of bone mineral density and bone micro-architecture of the femoral head that harvested from the three-foot bearing ethanol destroyed canine model for osteonecrosis of femoral head, and discuss the influences of local injection of ethanol and biomechanical loading to the structural properties of the femoral head. Methods Twenty-four Beagles were divided randomly into four-foot bearing canines and three-foot bearing canines. One fore-limb was fixed randomly in three-foot bearing canines. Osteonecrosis was induced in all experimental animals by local injection of 5 mL pure ethanol into one side of the femoral head. The hind limbs injected with NS were acted as control group, that of three-foot canines injected with ethanol were acted as three-foot canine group, and that of four-foot canines injected with ethanol were acted as four-foot canine group. The contralateral femoral head was injected into equal amount of NS. Animals were sacrificed at the time intervals of 1, 3, 6, and 12 weeks after the injection of ethanol. Quantitative micro- computed tomography was used to characterize changes in bone micro-architecture and bone mineral density of femoral head. Results The clear three-dimensional model of trabecular bone of necrotic femoral head were obtained. There were no significant differences among 3 groups according to the time line by 1 week after ethanol injection（P 〉 0.05）. At 3 weeks after injection of ethanol, in three-foot canine group and four-foot canine group, the volume of BMC, BMD, BVF, and BS/BV increased gradually as the distance to the drilling canal increased. There were significant differences between 3 regions （P 〈 0.05）. At 6 weeks, in three-foot canine group and four-foot canine group, the volume of BMC, BMD,BVF, and Tb.N of region Ⅰ and Ⅱ decreased significantly compared with region Ⅲ （P 〈 0.05）. At 12 weeks, there are no differences among 3 groups （P 〉 0.05）. There were significant decreases in BMD values, BVF, BS/BV, Tb.N, Tb.Sp and Tb.Th after the injection of pure ethanol. And, the changes were more and more obvious by the time line. These changes were differentiable at 3 weeks after injection of ethanol, and became obvious at 6 weeks. These changes were more obvious at the part that near the injection canal. The changes in three- foot canine group were more obvious than that in four-foot canine group. Conclusion Resorption of necrotic compact bone trabecular may weaken the structural properties of the femoral head. Moreover, remodeling and repairing process of necrotic bone trabecular may be hampered by constant biomechanical loading that presented in three-foot bearing canines, and thereby further weaken the structural properties of the femoral head. Biomechanical loading may be one of the critical reasons that lead to the collapse of femoral head.
出处
《中国修复重建外科杂志》
CAS
CSCD
北大核心
2008年第3期281-289,共9页
Chinese Journal of Reparative and Reconstructive Surgery
基金
上海市科学技术委员会重点资助项目(054119506)~~
