低频可控性微动影响长骨骨折愈合的实验研究

Experimental study on influence of controlled low frequency micromovement on fracture healing

目的应用可控性微动外固定支架研究骨折端低频微动对骨痂增殖和骨折愈合的影响。方法绵羊39只,双侧胫骨中段横行截骨,间隙2mm,用连有微动装置的单边外固定支架固定。术后10d,随机选择一侧肢体进行微动,按不同的微动频率分为3组:A组0.5Hz,B组1Hz,C组5Hz;幅度为0.25mm,4周结束(30min/d)。另一侧肢体不微动,为对照组。分别于术后4、6、9周切取标本进行大体观察、X线检查、组织学检测及生物力学测试。结果大体与X线检查显示各实验组均有大量的骨痂生成,4周末达高峰;组织学检测显示微动组骨痂软骨内骨化与类骨质形成的速率在6周最为明显,均快于对照组,以B组形成速率最快。9周末生物力学测试微动组弯曲刚度均强于对照组,以B组的力学强度最大。结论骨折端低频微动在骨折愈合早期均能有效地促进骨痂生长,加速骨痂的矿化,以1Hz频率效果最佳。

Objective To investigate the influence of low frequency micromovement induced by an external fixator with controlled mieromovement device on callus formation and fracture healing. Methods 39 sheep were involved in the study. After transverse osteotomy with a gap of 2 mm was done at the mid-shaft of both tibias, the hind limbs were fixed with unilateral external fixators with controlled micromovement device, 10 days after osteotomy, one hind limb of the sheep was randomly selected to have micromovement. According to different micromovement frequencies, the sheep were randomly divided into 3 groups： Group A, 0. 5 Hertz; Group B, 1 Hertz; Group C, 5 Hertz. The micromovement had an amplitude of 0.25mm and stopped by the end of the fourth postoperative week （30 min/d）. The other hind limb of each sheep did not have micromovement and served as the control. Macrostructural and histological observations, radiographic examinations, and biomeehanical tests were done respectively at 4, 6, 9 weeks after osteotomy. Results Macrostructural observations and X-ray examinations revealed a large amount of callus formation with a peak at the end of the fourth postoperative week in the 3 experimental groups. Histological analysis showed faster endochondral ossification and osteoid formation in the experimental groups than in the control by the sixth postoperative week, with the highest rate in Group B （1Hz）. Biomechanical tests proved that the bending stiffness in the experimental groups was superior to that in the control, with the strongest in Group B （1 Hz）. Conclusions Low frequency-micromovement at the fracture sites can promote callus formation and accelerate mineralization at the early stage of fracture healing. A frequency of 1Hz can produce the best results.