[The effect of yttrium-90 radio synovectomy on the intra-articular xenon-133 clearance in rheumatic joint diseases].

Nine inflamed knee joints out of eight patients were examined before and after intraarticular injection of yttrium-90 silicate colloid, in order to find out the effect of radiation synovectomy on the perfusion of the joints. These joints and the untreated contralateral knee joints were examined as to the clinical status and the fast component Tf of the xenon-133 clearance was determined as a means of the perfusion of the synovium. A linear correlation exists between the clinical status of the knee joint and the perfusion as determined by Tf measured three months before and after injection of yttrium-90. Also the joints without any radiation synovectomy showed this correlation. Three months after radiation synovectomy with yttrium-90 there was still no therapeutic effect apparent in the majority of the inflamed knee joints (seven out of nine). At this stage there still existed a hyperaemia. Therefore, it seems that on the whole three months are too short a period to judge the therapeutic effect.