Holmium-laser synovectomy was carried out to remove allergically inflamed synovial membranes in rabbit knee joints. The healing process was then investigated at different periods. Left knee joints of 12 rabbits were exposed to Ho:YAG-laser radiation at a wavelength of 2.1 microns, pulse energy of 600 mJ, pulse length of 1 ms, and repetition rate of 3 Hz. Twelve others were treated conventionally and 12 served as controls. After 1 day, 1 week, and 1 and 3 months, respectively, 3 animals from each group were sacrificed and the synovialis grossly and microscopically examined. Coagulation necrosis, inflammation, and edema resulted following laser therapy. After 1 week, the synovial layer consisted of a scarlike formation of fibers and within 1 month, its surface appeared smooth. The mechanical abrasion caused hemorrhage and necrosis. Fibrosis developed in the capsular layers, and after 3 months, the surface appeared coarse and villous. Based on these preliminary findings, holmium-laser synovectomy may offer an alternative method to existing therapeutic techniques.

The aim of this work was to investigate and evaluate the tissue reactions after sham operation and after mechanical and holmium laser chondral debridement in a rabbit model at different postoperative intervals. In 27 rabbits an arthrosis was induced by implantation of a piece of polyethylene sheeting in one knee joint. After 5 months, distinct arthritic changes had developed. Nine animals each were randomized for sham operation, mechanical debridement, and holmium laser chondral debridement. At 1 day, 1 month, and 3 months postoperatively, three animals in each group were sacrificed and their joints examined grossly and microscopically. At 3 months after mechanical debridement the articular surface was relatively smooth, and tears and defects were filled with fibrous repair tissue. After holmium laser debridement chondral necroses were regularly found, occasionally with damage to the subchondral bone and distinct inflammation in the marrow space. The articular surface remained rough and uneven. These preliminary results suggest that use of the holmium laser is not superior to mechanical methods for remodelling and smoothing of fairly large chondral areas.

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.

The goal of this investigation was to improve the reliability of intraoperative and postoperative hemostasis and to observe the healing process after using a combined technique of tissue freezing followed by the application of collagen fleece and fibrin glue for the treatment of splenic ruptures. Grade II lesions were inflicted on the spleens of 15 swine. The bleeding wounds were frozen for 1 min at -60 degrees C using a cryosurgical device. Immediately afterwards the frozen lesions were covered with fibrin glue and collagen fleece and kept under slight compression. In every case complete hemostasis was achieved intraoperatively. The spleens of three animals each time were collected for gross and microscopic examination after 2 days and 1, 2, 5, and 6 weeks. A visceroperitoneal adhesion was observed in only one spleen, U-shaped viscerovisceral adhesions in five spleens. Superficial coagulation necroses could be detected microscopically only after 2 days and 1 week. Organization of the wounds, indicated by granulation tissue which contained siderophages, started in the 2nd week. There was distinct formation of collagen fibers after 5 and 6 weeks; only a residue of the collagen fleece was visible and the surplus fibrin glue was encapsulated. With this combined technique complete and safe hemostasis and a good subsequent healing process was achieved.