Computerized tomography of the distal radioulnar joint: correlation with ligamentous pathology in a cadaveric model.

The kinematics of the normal distal radioulnar joint (DRUJ) and the stabilizing function of various structures about the DRUJ were investigated in a study involving six fresh frozen cadavers. Sequential division of the supporting structures was correlated with abnormalities detected by computerized tomography (CT). The infratendinous portion of the extensor carpi ulnaris is a major restraint against dorsal and palmar subluxation. Division of the radioulnar ligaments and triangular fibrocartilage alone produced only minor changes. Lateral displacement was controlled by the interosseous membrane and the pronator quadratus. CT is a useful method of gaining objective and quantifiable information regarding incongruity of the DRUJ. Three scans--one each in pronation, neutral, and supination--would be optimal. The pronation scan is likely to detect palmar subluxation, while the neutral scan is sensitive for dorsal subluxation and DRUJ diastasis. The supination view should confirm reduction of any subluxation. An important observation of this study was the spontaneous reduction of palmar, dorsal, and lateral displacement in supination. This suggests that immobilization in supination may be indicated in cases of acute DRUJ injury.