title: Stabilization of costal cartilage graft warping using infrared laser irradiation in a porcine model.
abstract: OBJECTIVE
  To develop a method to rapidly stabilize the shape change process in peripheral slices of costal cartilage by using infrared laser irradiation in a porcine model.
  
  
  METHODS
  Forty peripheral porcine costal cartilage specimens (40 × 10 × 2 mm) were harvested. Thirty of these specimens were immediately irradiated with an Nd:YAG laser (λ = 1.32 μm; spot size, 2-mm diameter) using 1 of 3 exposure treatments: 6 W, 2 seconds, and 4 spots; 8 W, 3 seconds, and 4 spots; or 6 W, 2 seconds, and 8 spots. Ten control specimens were only immersed in 0.9% saline solution. Angle of curvature was measured from photographs taken at 0 minutes, immediately after irradiation, and at 30 minutes, 1 hour, 5 hours, and 24 hours. Infrared imaging was used to measure surface temperatures during irradiation. Cell viability after irradiation was determined using a live/dead assay in conjunction with fluorescent confocal microscopy.
  
  
  RESULTS
  Compared with the untreated controls, the irradiated grafts underwent accelerated shape change within the first 30 minutes to reach a stable geometry. Thereafter, irradiated grafts underwent little or no shape change, whereas the control group exhibited significant change in curvature from 30 minutes to 24 hours (P < .001). The average peak irradiated spot temperatures ranged from 76°C to 82°C. Cell viability measurements at the laser spot sites demonstrated a hemispherically shaped region of dead cells with a depth of 0.8 to 1.2 mm and a surface diameter of 1.9 to 2.7 mm.
  
  
  CONCLUSIONS
  Laser irradiation of peripheral costal cartilage slices provides an effective method for rapidly stabilizing acute shape change by accelerating the warping process. The temperature elevations necessary to achieve this are spatially limited and well within the limits of tolerable tissue injury.
authors.affiliation: Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Rd E, University of California, Irvine, CA 92612, USA.
authors.forename: Allen
authors.initials: A
authors.lastname: Foulad
authors.forename: Pedram
authors.initials: P
authors.lastname: Ghasri
authors.forename: Rohit
authors.initials: R
authors.lastname: Garg
authors.forename: Brian
authors.initials: B
authors.lastname: Wong
mesh_terms: D000818:Animals; D002356:Cartilage / Q000528:radiation effects*; D007259:Infrared Rays; D053844:Lasers, Solid-State; D028022:Low-Level Light Therapy; D023421:Models, Animal; D012272:Ribs / Q000528:radiation effects*; D013048:Specimen Handling; D013552:Swine; D020858:Tissue and Organ Harvesting; D019737:Transplants