外固定器轴向加压后骨折断端压力变化的在体实验研究

THE EXPERIMENTAL STUDY ABOUT VARIATION OF PRESSURE ON FRACTURE SITE PRESSED AXIALLY BY EXTERNAL FIXATOR IN VIVO

为了探讨骨折断端压力的在体测试方法 ,定量分析外固定器轴向加压后在体骨折断端压力变化规律 ,将 30只大耳白兔随机分为 3组 ,左侧胫骨中段横形截骨 ,分别用外固定器加载 0 .5、1、1.5倍动物体重。以固定针上的应变片为传感器测得加压量 (骨折断端压力 ) 应变片电压定标曲线。在轴向加压术后 2 4h内连续测量应变片电压变化 ,并通过加压量 (骨折断端压力 ) 应变片电压定标曲线转化为骨折断端压力变化。结果 :外固定器轴向加压后 2 4h内在体骨折断端压力持续衰减 ,3组骨折断端压力变化速率经t检验有显著性差异 (P <0 .0 5 )。结论认为 :外固定器应变测量可用于在体骨折断端压力测试 ;外固定器轴向加压后在体骨折断端压力迅速衰减 ,加压量越大衰减速率越快。

Objective: In this work, animal experiments were designed to investigate the way of measuring pressure on fracture site and analyze the pressure variation with different axial pressure at different term fixing in vivo qaantitively. Methods: The model from which the pressure on fracture site could be measured was set up. 30 rabbits were randomly divided into 3 groups and the press loading was 1.5, 1, 0.5 times weight respectively. Transverse left tibial osteotomies were performed and the tibias were fixed with a external fixator. A strain gauge was adhered to the pin. The strain gauge voltage was measured continually for 24 hours. The results of strain gauge voltage were transformed to the pressure on fracture site by 'Strain Gauge Voltage-Pressure curves'. Results: The pressure on fracture site in vivo kept declining in 24 hours when the bones were pressed axially with external fixators. The variation rates of pressure on fracture site in vivo in 3 groups were significantly different (P<0.05). Conclusions: The strain measurement of extemal fixator could fit the pressure measurement on fracture site in vivo. The pressure on fracture site in vivo declined rapidly when bones in vivo were pressed axially with external fixators, heavier press induced faster declining.