radial ray defects

diagnosis

the sonographic findings in radial ray defects will depend on the specific disorder encountered and the severity of the lesion. the defect may be unilateral or bilateral with an absent or hypoplastic radius. the ulna is always present, however, but may be shorter (distal hypoplasia). joint abnormalities are often seen at the level of the wrist with the hand being radially deviated, lying perpendicular to a short, underdeveloped forearm (radial clubhand). the thumb may or may not be present, be normally developed or hypoplastic or have three phalanges (triphalangeal thumb). the metacarpals can also be affected. it may be difficult to differentiate sonographically between radius and ulna in the presence of a single forearm bone; the latter has a wider proximal end and typically a slight angulation between the upper and middle thirds.