The triangular fibrocartilage complex (TFCC): updated anatomy, variants, and MRI diagnostic pitfalls.

The triangular fibrocartilage complex (TFCC) is a key stabilizer of the ulnar wrist, integrating both the distal radioulnar and ulnocarpal joints. Recent advances in arthroscopic anatomy have led to a three-dimensional, tripartite conceptualization of the TFCC, describing it as comprising three interconnected components: the articular disc, the distal radioulnar ligaments providing primary stability, and a continuous peripheral capsular structure, or "peripheral wall," which encompasses the palmar and dorsal ulnocarpal ligaments, the meniscus homologue, and the extensor carpi ulnaris tendon sheath. Vascular supply is concentrated at the peripheral insertions, while the central disc is relatively avascular, influencing its healing potential. Functionally, the TFCC contributes to both rotational and translational stability of the radioulnocarpal articulation, with the distal radioulnar ligaments serving as the primary stabilizers and the ulnocarpal ligament complex, extensor carpi ulnaris tendon sheath, and interosseous membrane providing secondary support. MRI, particularly three-dimensional isotropic sequences and MR arthrography, allows detailed visualization of the TFCC components, detection of partial or complete tears, and differentiation between normal anatomic variants and pathologic abnormalities. Recognition of normal variations and positional changes related to forearm rotation is essential to avoid diagnostic errors. This review integrates arthroscopic, anatomical, biomechanical, and imaging perspectives, providing a comprehensive understanding of the TFCC and its updated conceptual framework, with direct implications for clinical assessment, surgical planning, and post-treatment follow-up of ulnar wrist injuries.