钢板固定对犬胫骨生物力学性能影响的实验研究

Experimental Study on the Effects of the Plates Fixation on Intact Canine Bone Mechanical Properties

钢板内固定后所致的局部骨质疏松是钢板取出后再骨折的主要原因。方法:本实验采用316l医用不锈钢制成的三种不同力学性能的4孔钢板固定在犬完整胫骨中段,以单纯普通皮质骨螺丝钉固定作对照组。用静态应变仪测量不同条件下的胫骨应变值,观察活体骨组织不同时期骨CT片灰度变化及测试扭力。结果:上述不同的方法固定均可使局部产生骨质疏松,其程度与钢板的刚度成正比关系,但随时间延长这种骨质疏松可逐渐减轻。生物力学测试表明随着骨质疏松的减轻,骨质的力学性能亦逐渐恢复,但术后5个月时仍未恢复到固定初期水平。

Three types of plate made of 316L medical stainless steel were applied in the experiment . They were divided into conventional plate, concave plate and sliding plate by their different shapes and functions. They were fixed on intact canine tibias and compared with intact canine tib-ias that were only fixed with conventional screws. The stress values were measured with static strain instrument on different conditions in vitro. Bone tissue was scanned with CT and torsional strength measured on different stages. The experimental results proved that local osteoporosity extent was in proportion to plate stiffiness. The osteoporosity was increasingly reducing as time went on. The result of torsional strength measuring confirmed that bone strength could not recover approaching to initial level in 5 months postoperatively.