Holmium‐laser synovectomy of immune synovitis in rabbits

Abstract

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.

Comparison of surgical techniques for synovectomy in New Zealand White rabbits with induced inflammatory arthritis

“…This difference can be explained by the decreased degree of immunosensitization used in our study, compared with the degree used in other studies. Other investigators 18,19,25 identified substantial effusion, lameness, and gross pathologic changes following immunosensitization. Investigators in those studies administered 2 doses of ovalbumin, ID, prior to intraarticular injection.…”

“…Our study had a design similar to that of other studies 17,19 in which investigators used antigen-induced arthritis in rabbits to evaluate various modalities of surgical synovectomy. However, complications encountered in our study differed from those in the other reports.…”

“…17 Intra-articular injection of ovalbumin after immunosensitization produces reliable inflammatory arthritis in rabbits that can be used to create a method for studying immune-mediated inflammatory arthritis and other immune-mediated arthropathies. [17][18][19] In in vitro and clinical studies, 20-23 radiofrequency energy has been used to thermally modify intra-articular soft tissue structures, which causes shrinkage of collagenous tissue and articular cartilage. Evaluation of the capsular changes in those studies revealed local synovial ablation when thermal energy was delivered to the joint capsule.…”

“…17,18 Although arthroscopic synovectomy has been evaluated in larger animals, investigators that have used rabbits prefer an open arthrotomy procedure because of the limited size of the femoropatellar joint. 17,19 For this reason, we selected an…”

Photodynamic therapy for rheumatoid arthritis?

“…Excimer lasers can be used via an arthroscope, but ablation rates are too low [10]. At present, the best laser system for arthroscopic application seems to be the Ho:YAG, which combines a high ablation rate with acceptable thermal side effects and the possibility of using it in a fluid medium [11][12][13]. But even with the Ho:YAG laser, synovectomy is more time-consuming than with a mechanical device.…”