Zemek Allison J, Protsenko Dmitry E, Wong Brian J F
Beckman Laser Institute and Medical Clinic, University of California Irvine, Irvine, California 92697, USA.
Lasers Surg Med. 2012 Sep;44(7):572-9. doi: 10.1002/lsm.22057. Epub 2012 Aug 6.
Thermally mediated modalities of cartilage reshaping utilize localized heating of cartilage combined with mechanical deformation to achieve new geometries. We sought to determine the steady state elastic modulus of thermally modified cartilage without deformation, as this provides a constraint in mechanical models of the shape change process.
STUDY DESIGN/MATERIALS AND METHODS: The main objective of this study was to characterize the steady state elastic modulus of porcine septal cartilage after uniform heating with radiofrequency (RF) to peak temperatures of 50 ± 5, 65 ± 5, and 85 ± 5°C. The cartilage was divided into three equally sized regions, designated as anterior, middle and posterior. Each region was then sectioned into two specimens with the proximal component serving as a paired control.
The data confirm that there is high baseline variability in control steady state elastic moduli between animals. Also, the control values confirm a decreasing steady state elastic modulus from anterior to posterior. There is no statistical significance (P > 0.05) found between the elastic moduli of control and treated samples.
Although shape change and retention have been fairly well characterized, little is known about the specific relation between steady state elastic modulus of cartilage and maximum treatment temperature. We determined that the difference of steady state elastic modulus between control and treated porcine septal samples was not statistically significant after uniform heating with RF to peak temperatures of 50 ± 5, 65 ± 5, and 85 ± 5°C. Ultimately, the results of this study do not pertain to the regions of heated cartilage that are shaped to hold a new form; however, it does show that the regions that are not mechanically deformed do return to the original pre-treatment elastic modulus. This is still useful information that may be used in finite element models to predict changes in internal stress distributions of cartilage after laser reshaping.
热介导的软骨重塑方式利用软骨的局部加热并结合机械变形来实现新的几何形状。我们试图确定未经变形的热改性软骨的稳态弹性模量，因为这在形状变化过程的力学模型中提供了一个约束条件。
研究设计/材料与方法：本研究的主要目的是表征经射频（RF）均匀加热至峰值温度50±5、65±5和85±5°C后猪鼻中隔软骨的稳态弹性模量。将软骨分为三个大小相等的区域，分别指定为前部、中部和后部。然后将每个区域切成两个标本，近端部分作为配对对照。
数据证实，动物之间对照稳态弹性模量存在较高的基线变异性。此外，对照值证实稳态弹性模量从前部到后部逐渐降低。对照样本和处理样本的弹性模量之间未发现统计学显著性差异（P>0.05）。
尽管形状变化和保持已经得到了较好的表征，但关于软骨稳态弹性模量与最大治疗温度之间的具体关系知之甚少。我们确定在用射频均匀加热至峰值温度50±5、65±5和85±5°C后，对照猪鼻中隔样本和处理样本之间的稳态弹性模量差异无统计学意义。最终，本研究结果不适用于经塑形以保持新形状的加热软骨区域；然而，可以表明未发生机械变形区域确实恢复到治疗前的原始弹性模量水平。这仍然是有用的信息，可以用于有限元模型中预测激光重塑后软骨内部应力分布的变化。
