133Xe clearance of the knee joint of patients suffering from arthritis and osteoarthrosis

65 inflammed and 13 non-inflammed knee joints of patients suffering from osteoarthrosis were examined by the Xe133 clearance method. The control group consisted of 27 patients with exsudative arthritis of the knee. The counts of 80 μC 133Xe given intraarticcularly were measured above the knee joint by NK 350 energy selective counter. The time needed to halve the count rate measured in the 4th minute after administration (biological half life [T1/2]) was significantly different in the three groups. It was the longest in the non-inflammed arthrosis, the shortest in the exsudative arthritis group. Significant differences were apparent regarding joint pain and tenderness in all the three groups. Though the synovial protein level and the C3 complement level were significantly different, in the three groups no relationship was found between the T1/2 and synovial/serum protein ratio or between the synovial/serum C3 ratio. The authors concluded that 133Xe clearance, which measures the perfusion of the synovial membrane, can be used for measuring the inflammatory activity of knee joint synovitis. (author)