• ABSTRACT
    • Entrapment of the extensor carpi ulnaris (ECU) tendon between the ulnar head and the sigmoid notch of the radius occurred in a 12-year-old boy. This led to an irreducible dorsal dislocation of the distal radioulnar joint (DRUJ). Irreducible DRUJ dislocations are uncommon, and the entrapped ECU has not been previously described in a skeletally immature patient. The physical and roentgenographic findings of a dorsally displaced ulna, a widened DRUJ, and the inability to obtain a closed reduction should alert the examiner to the need for exploration. A dorsal exposure is required to free the ECU and reconstruct the triangular fibrocartilage complex.