Hydroxide: A First Experience

Radiation synovectomy (RS) is indicated when conventional pharmacologic treatment of chronic synovitis has not relieved its symptoms. The use of radionuclides that are bound to ferric hydroxide (FH) particles has been shown to be effective and safe for this procedure. 166Ho-FH macroaggregates offer promising properties for RS but there is a lack of clinical data. We investigated the efficacy and safety of 166Ho-FH in a prospective clinical trial in patients suffering from chronic synovitis. Methods: Twenty-four intraarticular injections were performed in 22 patients receiving a mean activity of 1.11 GBq (range, 0.77–1.24 GBq) 166Ho-FH. Blood activity measurements and monitoring of activity distribution were performed by whole-body gammacamera imaging for control of leakage 3 and 24 h after injection of 166Ho-FH. The patients were evaluated clinically before RS, 1 wk and 1 mo after the treatment, and thereafter in 3-mo intervals by assessing joint effusion, pannus, local pain, range of motion, and the patient’s satisfaction. Results: In 18 of 24 treatments, no leakage to nontarget organs was visible, whereas small amounts of activity could be detected in the local inguinal lymph nodes in 6 patients and to the lungs and to the liver in 1 patient ( 0.1%). In all cases leakage to the lymph nodes was 1%. Leakage to the blood was negligible. Clinically, 17 patients (71%) exhibited a complete or partial response. Conclusion: RS with 166Ho-FH was safe and effective in patients with chronic synovitis of different origin. Controlled clinical trials are necessary to evaluate the therapeutic efficacy and safety compared with the treatment with other radionuclides and glucocorticosteroids.