MATRIX ASSESSMENT OF THE ARTICULAR-CARTILAGE SURFACE AFTER CHONDROPLASTY WITH THE HOLMIUM-YAG LASER

The goal of this study was to evaluate, histologically and biochemical ly, repair of the articular cartilage in a rabbit joint after the use of the holmium:yttrium-aluminum-garnet laser in a cartilage chondropla sty model. In 30 New Zealand White rabbits, chondroplasty was performe d with the laser at an intensity of 0.8 J at a rate of 10 Hz. The anim als were sacrificed 12 weeks after surgery. Histologically, the safran in O staining index of proteoglycan correlated well with the biochemic al results, illustrating a decrease of proteoglycan in the repaired ar ticular cartilage after laser articular cartilage chondroplasty. The d amaged articular cartilage surface after the laser application was ext ensive. The damaged area observed was gradually distributed along the radius from the central point of the laser beam application. Biochemic ally, the amount of glycosaminoglycan in the repaired tissue (8 +/- 2 mg of hexosamine per gram of dry cartilage) was statistically less whe n compared with that in the sham-treated tissue (40 +/- 5 mg). The amo unt of sulfate incorporated into proteoglycans was 8 to 10 times less in the chondroplasty model compared with the control, suggesting that cell viability was greatly reduced in the treated tissues or expressio n of proteoglycans was greatly reduced. In the subchondral area, histo logic evaluation showed the lack of osteocytes in lacunae of the bone tissue after use of laser energy. The architecture of the subchondral bone in the chondroplasty area was damaged, with damage also seen in t he membranes of the blood vessels.