Peripheral Lesions of the Triangular Fibrocartilage Complex.

The recently introduced CUP classification of the triangular fibrocartilage complex divides the lesions into central (C), ulnar (U), and peripheral (P). The periphery of the triangular fibrocartilage complex consists of the meniscus homologue, the ulnocarpal joint capsule including the extensor carpi ulnaris tendon sheath, and the ulnotriquetral and ulnolunate ligaments. Peripheral triangular fibrocartilage complex lesions can occur in isolation or in combination with injuries of the ulnar insertions and/or the articular disk. Most commonly the meniscus homologue and dorsal capsule are affected. Magnetic resonance imaging and computed tomography/magnetic arthrography are used to assess peripheral lesions. The arthroscopic assessment of peripheral triangular fibrocartilage complex lesions is limited. To date, data on the clinical relevance of the radiologic reporting of peripheral lesions are lacking. This pictorial review illustrates typical peripheral lesions of the triangular fibrocartilage complex according to the CUP classification.