Irreducible dislocation of distal radial ulnar joint.

Volar dislocations of the distal radioulnar joint are often missed initially. Late closed reduction of this joint is generally unsuccessful. Even acute reductions of the distal radioulnar joint is often incomplete or unsuccessful. This is not the case for dorsal dislocations. Obstruction to reduction may be due to the contracted volar soft tissues in late cases or to the dynamic pull of the pronator quadratus acutely. A previously unrecognized cause for difficulty in reduction is the torn triangular fibrocartilaginous complex (TFCC). When the tear occurs at its dorsal insertion on the radius, leaving the TFCC attached to the volar radius and to the ulna, it may block the reduction of the ulnar head into the sigmoid notch. Open reduction is required in such cases with repair of the TFCC.