88 Triangular Fibrocartilage Complex Tears The high-resolution thin-section imaging afforded by high-field MRI allows for accurate assessment the triangular fibrocartilage (TFC) complex of the wrist—a key stabilizer of the radiocarpal and radioulnar joints. This complex consists of the triangular fibrocartilage, the extensor carpi ulnaris tendon sheath, and the meniscal homologue (fibrous tissue between the ulnar styloid and triquetrum), as well as the dorsal and volar radioulnar and ulnocarpal ligaments. The proximal portion of the TFC complex arises from the lunate fossa of the radius and inserts at the ulnar styloid tip and fovea. Distal insertions include the triquetrum, hamate, and fifth metacarpal base. The complex inserts volarly on the triquetrum and lunate, and dorsally upon the extensor carpi ulnaris tendon sheath. The TFC proper (also known as the articular disk) cushions the radiocarpal and radioulnar joints and is the most commonly injured portion of the complex. It is best visualized as a hypointense (due to its fibrocartilaginous composition) biconcave structure on coronal images. On axial scans, the TFC appears triangular, its apex at the ulnar styloid. Its anterior and posterior boundaries are the radioulnar ligaments (dorsal and volar, respectively). TFC defects are characterized as traumatic or degenerative under the Palmer classification. The former, often caused by a direct blow, are more likely to occur at the TFC’s thicker radial attachment. Due to normal poor vascularity of this area such tears are unlikely to heal, and the injured TFC is often resected. Such defects constitute Palmer class 1 lesions, one type of which (class 1A) is illustrated on the MR arthrogram in Fig. 88.1. On this FS T1WI, the hypointense TFC demonstrates a 1-mm region of complete discontinuity (black arrow
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
