High frequency of ultrasonographic effusion in interphalangeal joints of healthy subjects: a descriptive study

To describe echographic abnormalities on the proximal (PIP) and distal (DIP) interphalangeal joints of healthy subjects.

Healthy asymptomatic volunteers under forty were enrolled. Ultrasonography was performed on PIP and DIP 2-5 in the presence of two operators. In B mode, synovial hypertophy and effusion were defined with the OMERACT criteria. In power Doppler mode, the inflammatory activity was evaluated.

46 subjects were enrolled: mean age 25.5 years, 89% right handed. 368 PIPs and DIPs were scanned. Effusion was found in 19.6% of dominant PIPs versus 22.3% of non-dominant PIPs (p>0.05). Effusion could be uni- or bilateral. DIP effusion was less frequent (3% DIPs). Average size of effusion was 0.83+/-0.25 mm for PIP and 0.72+/-0.16 mm for DIP.

Our study proposes a descriptive analysis of the PIP and the DIP joints. It confirms, with a bigger number of studied joints, the possible existence of a physiological effusion of the PIP of healthy subjects. It is the first descriptive study of the normal DIP where the presence of an effusion is very rare.