Isaksson Hanna, Gröngröft Ina, Wilson Wouter, van Donkelaar Corrinus C, van Rietbergen Bert, Tami Andrea, Huiskes Rik, Ito Keita
AO Research Institute, Davos, Switzerland.
J Orthop Res. 2009 May;27(5):664-72. doi: 10.1002/jor.20725.
During the remodeling phase of fracture healing in mice, the callus gradually transforms into a double cortex, which thereafter merges into one cortex. In large animals, a double cortex normally does not form. We investigated whether these patterns of remodeling of the fracture callus in mice can be explained by mechanical loading. Morphologies of fractures after 21, 28, and 42 days of healing were determined from an in vivo mid-diaphyseal femoral osteotomy healing experiment in mice. Bone density distributions from microCT at 21 days were converted into adaptive finite element models. To assess the effect of loading mode on bone remodeling, a well-established remodeling algorithm was used to examine the effect of axial force or bending moment on bone structure. All simulations predicted that under axial loading, the callus remodeled to form a single cortex. When a bending moment was applied, dual concentric cortices developed in all simulations, corresponding well to the progression of remodeling observed experimentally and resulting in quantitatively comparable callus areas of woven and lamellar bone. Effects of biological differences between species or other reasons cannot be excluded, but this study demonstrates how a difference in loading mode could explain the differences between the remodeling phase in small rodents and larger mammals.
在小鼠骨折愈合的重塑阶段，骨痂逐渐转变为双皮质，随后合并为一个皮质。在大型动物中，通常不会形成双皮质。我们研究了小鼠骨折骨痂的这些重塑模式是否可以用机械负荷来解释。通过小鼠体内股骨干中段截骨愈合实验，确定了愈合21天、28天和42天后骨折的形态。将21天时microCT的骨密度分布转换为自适应有限元模型。为了评估加载模式对骨重塑的影响，使用一种成熟的重塑算法来研究轴向力或弯矩对骨结构的影响。所有模拟预测，在轴向加载下，骨痂重塑形成单一皮质。当施加弯矩时，所有模拟中均出现双同心皮质，与实验观察到的重塑进程非常吻合，并导致编织骨和板层骨的骨痂面积在数量上具有可比性。不能排除物种间生物学差异或其他原因的影响，但本研究证明了加载模式的差异如何解释小型啮齿动物和大型哺乳动物在重塑阶段的差异。
