The influence of gap size on the development of fracture union with a micro external fixator
The influence of gap size on the development of fracture union with a micro external fixator
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DOI：
10.1016/j.jmbbm.2019.07.015
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发表时间：
2019-11-01
影响因子：
3.9
通讯作者：
Blunn, Gordon
中科院分区：
文献类型：
--
作者：
Meeson, Richard;Moazen, Mehran;Blunn, Gordon
越来越多的大鼠股骨骨折模型被用于骨折愈合的临床前研究，然而，间隙大小的影响及其对机械生物学的影响还没有得到很好的理解。我们的目的是评估截骨间隙对截骨愈合的影响，在之前发表的保证愈合的极端情况之间12-14周龄雌性Wistar大鼠股骨截骨术用微型固定器稳定（钛块，碳纤维棒），截骨间隙为1.0 mm（n = 5），1.5 mm（n = 7），2.0 mm（n = 6）。5周后，取出左侧股骨。使用X线显微断层扫描截骨间隙，然后进行组织学评价。1.0 mm间隙的影像学愈合率（截骨处完全矿化骨桥接）是2.0 mm间隙的3倍。1.0 mm的间隙具有最大的骨痂（0.069 μ m（3））和骨体积（0.035 μ m（3））。骨痂和骨体积在2.0 mm间隙内约小50%。使用用外固定器固定的尸体大鼠股骨，在材料试验机位移与载荷输出上计算第0天结构刚度的机械评估。1.0、1.5和2.0 mm间隙的结构刚度分别为32.6 +/- 5.4、32.5 +/- 2.4和32.4 +/- 8.3 N/mm（p = 0.779）。使用跨越截骨间隙的微应变微型差动磁阻传感器测量截骨间隙位移的变化，计算骨折块间应变（IFS）。增加差距尺寸显著降低了IFS（p = 0.013）。1.0、1.5和2.0 mm间隙的平均“第0天”IFS分别为11.2 +/- 1.3、8.4 +/- 1.5和6.1 +/- 1.2%。1.5 mm间隙导致骨折愈合延迟5周，可能代表骨折愈合治疗的有用测试环境。增加间隙尺寸不影响结构刚度，但确实降低了“第0天”IFS，在1.0和2.0 mm间隙之间测量的骨不连增加了一倍，骨体积减少了一半。
Increasingly, the rat femoral fracture model is being used for preclinical investigations of fracture healing, however, the effect of gap size and its influence on mechanobiology is not well understood. We aimed to evaluate the influence of osteotomy gap on osteotomy healing between the previously published extremes of guaranteed union (0.5 mm) and non-union (3 mm) using this model.A femoral osteotomy in 12-14 week old female Wistar rats was stabilised with a micro fixator (titanium blocks, carbon fiber bars) with an osteotomy gap of 1.0 mm (n = 5), 1.5 mm (n = 7), 2.0 mm (n = 6). After five weeks, the left femur was retrieved. The osteotomy gap was scanned using X-ray microtomography and then histologically evaluated. The radiographic union rate (complete mineralised bone bridging across the osteotomy) was three times higher for the 1.0 mm than the 2.0 mm gap. The 1.0 mm gap had the largest callus (0.069 mu m(3)) and bone volume (0.035 mu m(3)). Callus and bone volume were approximately 50% smaller within the 2.0 mm gap.Using cadaveric rat femurs stabilised with the external fixator, day 0 mechanical assessment of construct stiffness was calculated on materials testing machine displacement vs load output. The construct stiffness for the 1.0, 1.5 and 2.0 mm gaps was 32.6 +/- 5.4, 32.5 +/- 2.4, and 32.4 +/- 8.3 N/mm (p = 0.779). Interfragmentary strain (IFS) was calculated using the change in osteotomy gap displacement as measured using microstrain miniature differential reluctance transducer spanning the osteotomy gap. Increasing the gap size significantly reduced the IFS (p = 0.013). The mean 'day 0' IFS for the 1.0, 1.5 and 2.0 mm gaps were 11.2 +/- 1.3, 8.4 +/- 1.5 and 6.1 +/- 1.2% respectively.A 1.5 mm gap resulted in a delayed fracture healing by 5 weeks and may represent a useful test environment for fracture healing therapy. Increasing gap size did not affect construct stiffness, but did reduce the 'day 0' IFS, with a doubling of non-union and halving of bone volume measured between 1.0 and 2.0 mm gaps.