One hundred and eleven patients who had seropositive rheumatoid
arthritis and persistent synovitis of the knee were treated with
intra-articular injection of 270 millicuries of dysprosium-165 bound to
ferric hydroxide macroaggregates. A two-year follow-up was available for
fifty-nine of the treated knees. Thirty-nine had a good result; nine, a
fair result; and eleven, a poor result. Of the twenty-five knees that had
Stage-I radiographic changes, nineteen had a good result. Of the
thirty-four knees that had Stage-II radiographic changes, twenty showed a
good result. Systemic spread of the radioactivity from the injected joint
was minimum. The mean whole-body dose was calculated to be 0.3 rad and that
to the liver twenty-four hours after injection, 3.2 rads. The results
indicated that dysprosium-165-ferric hydroxide macroaggregate is an
effective agent for performing radiation synovectomy, particularly in knees
that have Stage-I radiographic changes. Because of the minimum rate of
systemic spread of the dysprosium-165, it offers a definite advantage over
agents that previously have been used.