Presentation
A known case of rheumatoid arthritis.
Patient Data
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In addition to the erosive changes and periarticular osteoporosis routinely seen in rheumatoid arthritis, there is an erosion of the radial side of the distal radioulnar joint; known as the "scallop sign".
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Erosion of the radial side of the DRUJ; the scallop sign.
Case Discussion
The scallop sign is the term used to describe the scooped-out appearance of the sigmoid notch of the distal radius that results from synovial proliferation and bone erosion of the distal radioulnar joint. It is characterized by a sclerotic border indicating slow development.
According to Freiberg et al, the scallop sign correlates with a high risk for extensor tendon rupture 1.