Measurement of the elastic modulus of rabbit nasal septal cartilage during Nd:YAG (lambda = 1.32 microm) laser irradiation.
OBJECTIVE
The objective of this study was to quantitatively measure changes in the elastic moduli of rabbit nasal septal cartilage during laser heating. While the efficacy of laser cartilage reshaping has been established for use in nasal surgery, few studies have investigated the temperature-dependent viscoelastic behavior of cartilage.


METHODS
Cyclic force versus displacement curves were generated during the Nd:YAG laser (lambda = 1.32 microm, 10 second exposure time, 21.22 W/cm2) irradiation of cartilage specimens secured in cantilevered geometry. Samples were irradiated three times with 30 second cooling intervals between each laser exposure. Measurements were recorded before, during, and after laser irradiation, and then following complete rehydration in normal saline (NS) for 1 hour at 25 degrees C. Elastic modulus was calculated assuming linear viscoelastic behavior.


RESULTS
The elastic modulus in native tissue decreased during and after successive laser exposures from about 6 to 3.5 MPa. After rehydration, the modulus returned to near-baseline value. Surface temperature reached a maximum of 65 degrees C.


CONCLUSIONS
The laser irradiation of cartilage using parameters similar to those used in reshaping does not produce significant irreversible changes in the mechanical properties of the tissue. Measurement of the elastic modulus is an effective means of characterizing alterations in cartilage mechanical behavior during and after laser heating.
Chao
Kenneth K H
KK
Beckman Laser Institute and Medical Clinic, University of California Irvine, 1002 Health Sciences Road East, Irvine, California 92612, USA.
Ho
Ki-Hong Kevin
KH
Wong
Brian J F
BJ
D000818:Animals; D004548:Elasticity / Q000528:radiation effects*; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000379:methods*; D009300:Nasal Septum / Q000502:physiology* / Q000528:radiation effects*; D011817:Rabbits; D019651:Plastic Surgery Procedures / Q000379:methods*