Ultrasonography (US) is more sensitive in detecting erosions when compared with conventional radiography (CR).

Images below:

Pain and swelling in second MCP right and left.

CR and US scans obtained on the same day.

No erosions where reported on CR.

US shows a small erosion over the radial aspect of the MC head right and a large erosion left. Erosions are defined as breaks in the cortical contour seen in two perpendicular planes.