Long-term viability and mechanical behavior following laser cartilage reshaping.
OBJECTIVE
To investigate the long-term in vivo effect of laser dosimetry on rabbit septal cartilage integrity, viability, and mechanical behavior.


METHODS
Nasal septal cartilage specimens (control and irradiated pairs) were harvested from 18 rabbits. Specimens were mechanically deformed and irradiated with an Nd:YAG laser across a broad dosimetry range (4-8 W and 6-16 seconds). Treated specimens and controls were autologously implanted into a subperichondrial auricular pocket. Specimens were harvested an average +/- SD of 208 +/- 35 days later. Tissue integrity, histology, chondrocyte viability, and mechanical property evaluations were performed. Tissue damage results were compared with Monte Carlo simulation models.


RESULTS
All laser-irradiated specimens demonstrated variable tissue resorption and calcification, which increased with increased dosimetry. Elastic moduli of the specimens were significantly either lower or higher than controls (all P<.05). Viability assays illustrated a total loss of viable chondrocytes within the laser-irradiated zones in all treated specimens. Histologic examination confirmed these findings. Experimental results were consistent with damage profiles determined using numerical simulations.


CONCLUSIONS
The loss of structural integrity and chondrocyte viability observed across a broad dosimetry range underscores the importance of spatially selective heating methods prior to initiating application in human subjects.
Karam
Amir M
AM
Beckman Laser Institute, University of California, Irvine 92612, USA.
Protsenko
Dmitriy E
DE
Li
Chao
C
Wright
Ryan
R
Liaw
Lih-Huei L
LH
Milner
Thomas E
TE
Wong
Brian J F
BJ
D000818:Animals; D001696:Biomechanical Phenomena; D002356:Cartilage / Q000601:surgery*; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology; D053685:Laser Therapy / Q000379:methods*; D008954:Models, Biological; D009300:Nasal Septum / Q000601:surgery*; D011817:Rabbits; D012225:Rhinoplasty / Q000295:instrumentation*; D013995:Time; D014022:Tissue Survival / Q000502:physiology*