Hsieh Adam H, Hwang David, Ryan David A, Freeman Anike K, Kim Hyunchul
Fischell Department of Bioengineering, Orthopaedic Mechanobiology Laboratory, University of Maryland, College Park, MD 20742, USA.
Spine (Phila Pa 1976). 2009 May 1;34(10):998-1005. doi: 10.1097/BRS.0b013e31819c09c4.
In vivo experiments to examine physiologic consequences and in vitro tests to determine immediate biomechanical effects of anular injury by needle puncture.
To determine whether a relationship exists between induction of degenerative changes in anulus fibrosus (AF) and compromised disc biomechanical function according to injury size.
Various studies in intervertebral disc mechanics, degeneration, and regeneration involve the creation of a defect in the anulus fibrosus (AF). However, the impact of the puncture, itself, on biomechanical function and disc health are not understood.
For in vivo experiments, rat caudal discs subjected to percutaneous anular punctures using different gauge size hypodermic needles (18, 22, 26 g) and nonpunctured controls were examined histologically up to 4 weeks postsurgery. For in vitro biomechanical testing, healthy motion segments were isolated and their creep compression response assessed immediately after needle puncture.
We found that needle size-dependence of creep compression behavior paralleled the size-dependence of degenerative changes in the AF. Specifically, 18-g punctures resulted in inward bulging of the AF, lamellar disorganization, and cellular changes. These changes were not seen in 22- and 26-g punctured discs. Biomechanical tests showed that only 18-g needle punctures led to significant changes in disc mechanics. Importantly, a statistically significant association was found between needle sizes that caused biomechanical changes and induction of degenerative changes in the AF.
Our findings suggest that injury sizes large enough to disrupt biomechanical function are needed to drive degenerative changes in rat caudal disc AF. Based on the data, we believe that small anular defects become sealed, allowing the disc to function normally and the AF to heal. Larger defects appear to require longer wound closure times, and may prolong the duration of impaired disc function.
通过体内实验研究生理后果，并通过体外测试确定针刺造成的纤维环损伤的即时生物力学效应。
根据损伤大小，确定纤维环（AF）退变改变的诱导与椎间盘生物力学功能受损之间是否存在关联。
关于椎间盘力学、退变和再生的各种研究都涉及到纤维环（AF）缺损的创建。然而，穿刺本身对生物力学功能和椎间盘健康的影响尚不清楚。
在体内实验中，对使用不同规格皮下注射针（18G、22G、26G）进行经皮纤维环穿刺的大鼠尾椎间盘以及未穿刺的对照组进行术后长达4周的组织学检查。在体外生物力学测试中，分离健康的运动节段，并在针刺后立即评估其蠕变压缩反应。
我们发现蠕变压缩行为的针规格依赖性与AF退变改变的大小依赖性平行。具体而言，18G穿刺导致AF向内膨出、板层紊乱和细胞变化。在22G和26G穿刺的椎间盘中未观察到这些变化。生物力学测试表明，只有18G针刺导致椎间盘力学发生显著变化。重要的是，在导致生物力学变化的针规格与AF退变改变的诱导之间发现了具有统计学意义的关联。
我们的研究结果表明，需要足够大以破坏生物力学功能的损伤大小来驱动大鼠尾椎间盘AF的退变改变。基于这些数据，我们认为小的纤维环缺损会愈合，使椎间盘能够正常发挥功能，AF也能愈合。较大的缺损似乎需要更长的伤口闭合时间，并且可能会延长椎间盘功能受损的持续时间。
