Thermographic evaluation of intra-articular treatment with radioactive yttrium (90Y) in 62 rheumatoid knee joints.

A total of 62 rheumatoid knee joints were treated with intra-articular 90Y. Results were assessed by clinical, roentgenologic and thermographic examination after a six-month follow-up. The majority of the joints had moderate roentgenologic manifestations of RA before treatment. The roentgenologic stage of the disease did not change during the follow-up period. The thermographic heat emission pattern was pathologic in all cases prior to treatment. The clinical cure and improvement in the thermographic pattern were in agreement in 44 of 50 completely examined cases (88%). The thermographic pattern was unchanged or worse in six knees with a clinically satisfactory anti-inflammatory response. This is probably due to remaining deeper inflammatory activity or to the relatively short observation period of six months, during which time only the clinical symptoms disappeared, while hyperthermy based on increased vascularity remained. The thermographic pattern remained pathologic in all knees without a clinical response to 90Y. Thermography is a safe and reliable complementary method for recording the anti-inflammatory effect of irradiation synovectomy on rheumatoid knees.