EFFECTS OF HOLMIUM-YAG LASER ON EQUINE ARTICULAR-CARTILAGE AND SUBCHONDRAL BONE ADJACENT TO TRAUMATIC LESIONS - A HISTOPATHOLOGICAL ASSESSMENT

This study was performed to investigate the effects of holmium:yttrium -aluminum-garnet (Ho:YAG) laser energy on articular cartilage and subc hondral bone adjacent to traumatically created cartilage lesions in a continuous weight-bearing model. The 2.1-mum wavelength was delivered efficiently and precisely in hand-controlled contact and near-contact hard tissue arthroscopic surgery in a saline medium. Bilateral arthros copy was performed on normal antebrachiocarpal and intercarpal joints of four adult horses. One hundred twenty traumatic lesions were create d on three weight-bearing articular surfaces with a knife, curet, or m otorized burr. Depths of the lesions were partial and full thickness. Configurations of the lesions were lacerations, scrapes, and craters. Left limbs were used as controls. Right limb lesions were treated with various intensities of laser energy: 0.1, 0.16, and 0.2 J. Animals we re killed at intervals of 1, 3, and 8 weeks. Gross microscopic anatomy was documented, and tissue sections were subjected to blind review by a pathologist. Mankin grading for cellularity and proteoglycan conten t was used to qualitatively evaluate cartilage response. Cartilage adj acent to all lesions exposed to laser energy had better cellularity an d proteoglycan content (p < 0.05) than did corresponding controls by M ankin grading. Mankin grades for levels of 0.16 and 0.2 J were lower ( p < 0.05) than were those of controls or lesions exposed to 0.1 J. The re was loss of cellularity and necrosis in subchondral bone at higher energy levels (0.16 and 0.2 J). This study examined the effects of Ho: YAG laser on articular cartilage and subchondral bone in terms of dept h of damage and healing response over time in a weight-bearing model. Additional research to define dose-response curves for Ho:YAG laser tr eatment of cartilage and subchondral bone are indicated.