Prevalence of periarticular calcifications in pyrophosphate arthropathy and their relation to nodal osteoarthrosis.

X-rays of the shoulder, hand, and knee joints from 30 patients with pyrophosphate arthropathy (PA) and 30 age and sex matched control subjects were examined for periarticular, dense, homogeneous calcifications considered to be apatite deposits. They were found in 30% of the patients with PA compared with 3.3% of the controls. In addition in the PA group the incidence of Heberden's nodes was significantly increased in cases with periarticular calcifications, implying that mixed (calcium pyrophosphate dihydrate + apatite) crystal deposition disease could be related to nodal osteoarthrosis.