The pronator quadratus sign: its classification and diagnostic usefulness for injury and inflammation of the wrist.

The clinical value of the pronator quadratus radiological sign was investigated. Fresh undisplaced fractures of the distal radius and acute injuries of the distal radio-ulnar joint showed anterior displacement of the radiolucent shadow in 85% and 88% respectively, but normal subjects no displacement. In rheumatoid arthritis, the presence of synovitis of the wrist joint appeared to be correlated with a blurred shadow at the distal end.