提高脊柱骨折水平复位力量对Harrington分离棒应力分布的影响——二维光弹性实验研究

使用Edwards套棒可提高Harrington装置对脊柱骨折的解剖复位率,但同时使Harrington棒各点应力值呈线性增加,尤以套棒所在点受影响最大,然而总体应力分布趋势不变,棒体——齿棘区交界处应力集中为棒的危险断面,棒前侧应力值高于后侧;齿棘部高于棒体部。实验结果提示,临床应用Ebwards套捧时应注意将其安置在尽量远离危险断面处,并使危险断面尽量靠近上钩,以减少在交变应力作用下应力集中造成的Harrington棒疲劳断裂。

Studys of Stress Distribution of Harrington Distraction Rod While Increasing Horizontal Correcting Forces to Injuried Spine by Photoelasticity

The anatomic reduction rates of thoracic and lumbar spinal fractures were increased by Edwards devices, but the stresses on Harrington rods were risen linely. The point on Harrington rod where the rod-sleeve had been affected severely when the horizontal forces were increased, but the general curve characteristic of stress distribution were kept unchanged. The ratchet-shaft junction was the stress riser because of stress concentration. The stresses on anterior border of Harrinton rod were higher than on the posterior border. The stresses on ratchet part were much more than on smooth part. The results recommended that the rod-sleeve should be placed to the stress riser as fartther as possible, or the stress riser should be as closer to the upper hooks as possible in clinics in order to reduce the risk of mechanical failure of Harrington rods.