应用单平面和多平面截骨术矫治脊椎后凸实验中发生的生物力学损伤特征比较

背景关于单平面和多平面截骨术的临床应用研究已颇多,但两者间生物力学特点直接比较的实验结果不多.目的探讨单平面截骨Dick钉固定和多平面截骨Luque棒固定治疗脊椎后凸的生物力学损伤特点.设计随机分组观察对比实验.单位武汉大学人民医院骨科实验室.材料12具新鲜小牛胸腰段脊柱标本,年龄三四岁.方法实验于2002-09/2003-09武汉大学人民医院骨科实验室完成.将12具新鲜小牛胸腰段脊椎标本(T8～L5)随机分成完整组、单平面截骨Dick钉固定组(Dick组)和多平面截骨Luque棒固定组(Luque组),每组4具.以侧弯方式进行超生理负荷试验,损伤试验在Instron5500型万能材料试验机上以10mm/min的速度匀速度加载,直至标本发生骨折或脱位而屈服.记录截荷值的变化并观察损伤模式,绘制损伤试验的载荷-位移曲线.主要观察指标各组小牛脊柱标本损伤性右侧弯试验截荷-位移曲线.结果12具小牛脊柱标本均进入结果分析.完整组标本在3600 N的弯曲载荷下屈服,曲线形态缓和;单平面截骨Dick组在2 800N时屈服,曲线亦较缓和;多平面截骨Luque组加载至7160 N才屈服,抵抗力几乎直线下落至4 000 N以下,此后曲线平缓.结论实验中多平面截骨Luque棒固定的最大抗屈服能力稍优于单平面截骨Dick钉固定组,但不足以构成临床应用中决定取舍的依据,两种术式术后脊柱稳定性坚强可靠,有利于术后脊柱功能的恢复.

Biomechanical characteristics of one-level versus multilevel osteotomy for kyphosis correction

BACKGROUND: The clinical application of one-level osteotomy and multilevel osteotomy has been well documented, but currently few studies were reported to compare their biomechanical characteristics.OBJECTIVE: To investigate the biomechanical characteristics of one-level osteotomy with Dick screw fixation and multilevel osteotomy with Luque instrumentation in the treatment of kyphosis.DESIGN: Randomized comparative experiment.SETTING: Laboratory of the Department of Orthopedics, Renmin Hospital of Wuhan University.MATERIALS: Fresh specimens of thoracic and lumbar spinal segments obtained from 12 3 or 4-year-old calves.METHODS: The experiment was conducted in the laboratory of the Department of Orthopedics, Renmin Hospital of Wuhan University between September 2002 and September 2003. Fresh spinal segments T8-L5 from 12 calves were randomized into an intact group, Dick screw group with one-level osteotomy with Dick screw fixation and Luque group with multilevel osteotomy with Luque instrumentation, with 4 spesimens in each group. Lateral bending test of the specimens was performed to examine the physiological overload using an Instron 5 500 universal material testing machine at the constant speed of 10 mm/minute until fracture or dislocation was induced. Changes in the loading were recorded and the induced injuries observed to obtain the load-displacement curve of the injury test.MAIN OUTCOME MEASURES: The load-displacement curve of the destructive right bending test in each group.RESULTS:All the data of 12 canines were involved in the result analysis.The spinal segments of the intact group yielded to the force of 3 600 N with a flat and smooth load-displacement curve, and those of Dick screw group yielded to a load of 2 800 N with also a relatively flat curve, while in Luque group, the segments did not yield until a load of 7 160 N, followed by drastic decrease of the resistance to less than 4 000 N, generating a flat and smooth curve afterwards.CONCLUSION: Luque instrumentation is a little more preferable than Dick screw in terms of the maximum resistance, but this difference does not justify the clinical decision of their superiority. Both techniques benefit postoperative recovery of spinal function with strong stability.