[Comparative experimental studies of mechanical and holmium laser synovectomy]

The goal of this study was to evaluate tissue reactions in rabbit knees following laser synovectomy using a holmium:YAG laser (wavelength: 2.1 microns) and to compare these results with those found after conventional mechanical abrasion treatment. Chronic arthritis was immunologically induced in one knee joint each of 48 rabbits. Twelve served as controls, 12 were sham-operated, 12 were exposed to laser radiation, and 12 others were treated according to conventional methods. In the laser group, a pulse length of 1 ms at a repetition rate of 3 Hz resulted in a pulse energy of 600 mJ. After periods of 1 day, 1 week and 1 and 3 months, respectively, three animals from each group were sacrificed and the synovialis was examined macroscopically and histologically using light and electron microscopy. Edema, acute inflammation, and coagulation necrosis occurred immediately following laser therapy. After 1 week, the synovial layer showed slight fibrosis, which was comparable to that found in the controls. One month later the surface appeared to be smooth. The mechanical abrasion caused hemorrhage and necrosis. Fibrosis was pronounced in all capsular layers, and after 3 months the surface appeared coarse and villous in this group. Based on these preliminary findings, holmium-laser synovectomy may offer an alternative to existing therapeutic techniques in the treatment of rheumatoid arthritis. The arthroscopic approach could prevent additional capsular fibrosis associated with mechanical irritation.