Communicating defects of the triangular fibrocartilage complex without disruption of the triangular fibrocartilage: a report of two cases.

Perforations or communicating defects of the triangular fibrocartilage complex have been more commonly identified after Palmer published his classification system (J Hand Surg 1989;14A:594-606). To his variants of class 1B (traumatic) ulnar avulsion with or without distal ulnar fracture, a third category may be added: defects of the ulnar collateral ligament without any associated disruption of the triangular fibrocartilage. The ulnar collateral ligament can be defined as an ulnar capsular structure between the more discrete elements of the triangular fibrocartilage and the ulnar ligaments, with the defect or perforation being distal to the intact triangular fibrocartilage and exiting into the floor of the extensor carpi ulnaris sheath. We present 2 cases that illustrate the diagnosis, the use of both magnetic resonance imaging and arthrography to confirm the diagnosis, the associated dorsal ulnar cutaneous nerve pain distribution, and the open direct and retinacular flap repair.