Measurement of the elastic modulus of porcine septal cartilage specimens following Nd:YAG laser treatment

摘要

Abstract: In this study we measured the mechanical properties of porcine septal cartilage before and after Nd:YAG laser ($lambda equals 1.32 micrometer, 21.22 W/cm$+2$/) radiation using parameters and conditions encountered during laser-mediated cartilage reshaping. During laser irradiation, specimens were linearly translated at constant velocity while surface temperature was monitored radiometrically with a thermopile sensor. Irradiation was terminated when surface temperature reached approximately 70 degrees Celsius. Force versus displacement curves were generated in cantilevered specimens using a calibrated thin beam load cell and a single motorized micropositioner (velocity equals .762 mm/sec). Measurements were determined immediately before and after laser irradiation, and then following hydration in saline solution (40 minutes, 25 degrees Celsius). Elastic modulus was calculated using a model assuming linear viscoelastic behavior. Specimens boiled in saline (one hour, 100 degrees Celsius and then re-hydrated) were also evaluated as these tissues are completely denatured. The calculated moduli before and after irradiation were 4.86 plus or minus .145 and 1.166 plus or minus .055 Mpa respectively. Following re-hydration in saline, the modulus returned to near-baseline values (5.119 plus or minus .163 Mpa). In contrast, elasticity remained lower in specimens boiled and re-hydrated (3.25 plus or minus .130 Mpa). These findings suggest that cartilage matrix properties have not been significantly altered following laser irradiation and that the mechanical properties of the tissue are maintained. !32