Animal Experiment on CO2 Laser Discectomy

本研究旨在探讨年龄对椎间盘内治疗后椎间盘组织病理学变化的影响。材料与方法：15只青年猴和7只老年猴。全麻下经腹膜入路显露腰椎。将木瓜凝乳蛋白酶（500 u/0.1ml）或软骨素酶-ABC（2u/0.1ml）注入每个椎间盘。另外两个椎间盘通过CO2激光椎间盘切除术或髓核切除术治疗。给药后，以规定的时间间隔（最长96周）处死动物，并获得腰椎。T2加权MR（2.0特斯拉）图像的标本，以评估水含量。结果：治疗后2天，所有椎间盘在T2加权MR图像上显示信号强度降低。治疗后48周，所有椎间盘均显示与正常对照组相似。然而，在老年猴中，所有椎间盘在治疗后48周甚至96周表现出信号降低。番红-O染色显示，治疗后椎间盘髓核、纤维环和软骨终板的蛋白多糖消失。这些变化主要发生在老年组。虽然番红-O-在48周内恢复的年轻组，这是仍然失去了在老年group.CONCLUSION：这项研究表明，激光椎间盘切除术在治疗椎间盘突出症提供了独特的优势，但也表明，椎间盘退变后的治疗与受试者的年龄。

This study was undertaken to investigate the influence of the subject age to histopathological changes of the intervertebral discs after intradiscal therapy.MATERIALS AND METHODS: Fifteen young monkeys and seven aged monkeys were used. Under general anesthesia, lumbar spine was exposed through transperitoneal approach. Chymopapain(500u/0.1ml) or Chondroitinase-ABC (2u/0.1ml) was injected into each disc. Two other discs were treated by CO2 laser discectomy or nucleotomy. After treatment, the animals were sacrificed at prescribed intervals of up to 96 weeks, and lumbar vertebral columns were obtained. T2-weighted MR(2.0Tesla) images of the specimen was taken to evaluate water content. Safranin-O stainability was also compared.RESULTS: All discs showed decreased signal intensity on T2- weighted MR images two days after treatment. Forty-eight weeks after treatment, all discs showed similar to those of the normal control in the young monkeys. However, in aged monkeys, all discs demonstrated decreased signal 48 and even 96 weeks after treatment. Safranin-O staining revealed the disappearance of proteoglycan from the nucleus pulposus, inner annulus fibrosus, and cartilagenous endplates of the treated discs. These changes predominated in the aged group. Although Safranin-O stainability was recovered within 48 weeks in the young group, which was remained lost in the aged group.CONCLUSION: This study suggests that laser discectomy offers unique advantages in the treatment of disc herniation, but also demonstrated that the disc degeneration after treatment correlated with the subject age.