Effect of irradiation with a low-intensity diode laser on the metabolism of equine articular cartilage in vitro.
OBJECTIVE
To determine whether irradiation with a low-intensity diode laser, which produces radiation at a wavelength of 810 nm, will induce nonthermal enhancement of chondrocyte metabolism.


METHODS
144 grossly normal articular cartilage explants aseptically harvested from the femoral condyles of 6 adult horses.


METHODS
Treated cartilage explants were irradiated with a diode laser at 1 of 7 fluence levels that ranged from 8 to 1,600 J/cm2. Explants were incubated for 24 or 72 hours, labeled for 24 hours with [35S]Na2SO4, and assayed for newly synthesized sulfated glycosaminoglycan (GAG; measured incorporation of 35SO4) and endogenous GAG, chondroitin 6-sulfate (CS), and keratan sulfate (KS) content, using a dimethylmethylene blue assay. Laser-induced temperature changes were measured during irradiation with a diode laser and a neodymium:yttrium aluminum garnet (Nd:YAG) laser, which produces radiation at a wavelength of 1,064 nm, using conditions that were reported in previous studies to increase explant metabolism.


RESULTS
After incubation for 24 or 72 hours, rate of 33SO4 uptake or endogenous GAG, CS, or KS content in irradiated explants was not significantly different than in nonirradiated explants. Cartilage temperature increased < 4.75 C during diode laser application. Cartilage temperature increased 5 to 12 C during Nd:YAG laser application.


CONCLUSIONS
Minimal thermal increases in cartilage explants with use of a low-intensity diode laser resulted in no change in proteoglycan metabolism of chondrocytes. An increase in tissue temperature over a narrow range with use of a Nd:YAG laser may have contributed to the metabolic alteration of chondrocytes reported in previous studies.
Ebert
D W
DW
Biomedical Engineering Center, College of Veterinary Medicine, The Ohio State University, Columbus 43210, USA.
Bertone
A L
AL
Roberts
C
C
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism / Q000528:radiation effects*; D002809:Chondroitin Sulfates / Q000096:biosynthesis*; D004307:Dose-Response Relationship, Radiation; D005269:Femur; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D006736:Horses; D007632:Keratan Sulfate / Q000096:biosynthesis*; D007834:Lasers; D009924:Organ Culture Techniques; D013431:Sulfates / Q000378:metabolism; D013462:Sulfur Radioisotopes; D013816:Thermodynamics
D006025:Glycosaminoglycans; D013431:Sulfates; D013462:Sulfur Radioisotopes; D002809:Chondroitin Sulfates; D007632:Keratan Sulfate