Radiochemical synovectomy appears to be an effective means of decreasing inflammation, effusion, and pain in patients with rheumatoid arthritis. There has been much effort to find out a special material which can be used with the intraarticular injection for similar effect to operative synovectomy.
Since von Reis and Swensson reported that osmic acid could be used for the chemical synovectomyat 1951, it has been used clinically. But the articular cartilagenous change has not been clearly clarified.
Author injected 1 % osmic acid to 50 rabbit knees, then the change of the articular cartilage was observed grossly, radiologically, light microscopically and transmission electron microscopically. The following results were obtained.
1. Grossly, the colour of the cartilage was dark brown at the first day after injection. The degenerative change appeared at the twelfth week, and spread widely at the sixteenth week. -
2. Radiologically, the degenerative change appeared at the sixteenth week.
I Light microscopically, there was boundary between the superficial and deep layers at the second week. After then, the degenerative change progressed at the superficial layer through the eighth week. At the twelfth week, the surface layer of the articular cartilage was necrotic.
4. Transmission electron microscopically, there was destruction of the chondrocytes_of the superficial layer at the first day after injection. At the sixteenth week, the intracellular organells> of the chondrocytes dispersed extracellularly.
Above findings suggest that intraarticular osmic acid treatment seems not suitable for rheumatoid arthritis because osmic acid destructs articular cartilage.
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