Authors:
Maria Stella Peccin
Paulo Ricardo G da Silva
Department of Health Sciences, Federal University of Sa˜o Paulo, UNIFESP, Av. Ana Costa 95, 11060-001 Santos, SP, Brazil

Ana Claudia Muniz Renno
Daniel Araki Ribeiro
Department of Biosciences, Federal University of Sa˜o Paulo, UNIFESP, Av. Ana Costa 95, 11060-001 Santos, SP, Brazil

Objectives. The purpose of this study was to evaluate the influence of low-power helium-neon laser on cartilage damage using an experimental short-term assay in rabbits. Material and Methods. A total of 21 adult male New Zealand rabbits underwent bilateral knee cartilage damage using a spherical bur. Helium-neon laser light with power of 6 J/cm² and wavelength of 632.8 nm was applied on the left knees submitted to surgical procedures only. The right knees lesions served as negative control (nonexposed to laser therapy). All animals were randomized and seven animals were killed at postoperative days 7, 21, and 40 days. Results. At seven days, similar histopathological patterns were noted for laser exposed and nonexposed knees. At 21 days, the control group showed an organized fibrous tissue inside the lesion, whereas knees exposed to laser therapy pointed out a cartilage tissue filling the lesion in the majority of treated knees. At 40 days, a well-organized fibrous tissue filled fully the lesion in the control group. On the other hand, the laser exposed knees showed a hyaline cartilage filled the lesion completely. Conclusions. Taken together, these results indicate that a low-energy laser is able to induce cartilage neoformation after 40 days following therapy.