RA joints whose bone scan was positive are thought to have a subclinical abnormality even if there aren't any symptoms. Two hundred joints in 45 patients with positive 99m Tc -HMDP bone scan without clinical signs except in small joints in hands and feet were followed for 12 to 45 months (mean: 22 months) . The age of the patients ranged from 24 to 76 (average : 57) and they had suffered from RA from 4 to 30 years (mean: 14) .
Clinical signs such as pain and/or swelling appeared in 88 out of the 200 joints during the follow-up time. The new symptoms appeared frequently in the knee joint. There was no significant difference in the occurrence of the symptoms, however, between loaded and non-loaded joints. Those new symptoms were observed within 18 months in 79 % out of 88 joints.
It is therefore considered that bone scans are an useful means for prospective detection of inflammatory joints. Careful observation is necessary for at least 18 months for RA joints with positive scintigraphic findings.
