The effectiveness of intra-articular bleomycin versus methotrexate in a chronic synovitis model

Objective: To compare the effectiveness of methotrexate which was proven to be effective for rheumatoid arthritis and bleomycin in a synovitis model. Our aim was to show whether bleomycin could be used for chemical synovectomy purposes. Design: Experimental study Setting: Department of Orthopedics and Traumatology, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey Subjects: Fifteen mature New Zealand rabbits were studied. Synovitis was induced by repeated injections of lambda carrageenan. Interventions: Knees of the subjects were grouped as sham, bleomycin and methotrexate. After synovitis occurred, sterile saline injected knees formed the sham group, bleomycin and methotrexate injected knees composed the study groups. In the 9th week of the study, animals were euthanised. Standard specimens were harvested from all knees. Immunoperoxidase staining was performed. Main outcome measures: The intensity of synovitis was evaluated with thickness of the synovial cell layers, intensity of inflammatory infiltrate and iNOS expression in cells. Results: Thickness of the synovial cell layers was greater in the sham group than in the study groups (p<0.05). Intensity of inflammatory infiltrate, lymphoplasmacytoid infiltrate, and histiocytes in the sham group were greater than in the study groups (p<0.05). iNOS expression in histocytes and plasma cells was significantly decreased in the study groups compared to sham operated group (p<0.05). There was no statistically significant difference between bleomycin and methotrexate groups with respect to synovial cell layer thickness and lymphoplasmacytoid infiltrate. Conclusions: According to these results, intraarticular bleomycin seems as effective as methotrexate in experimental synovitis model.