TFCC Injury

A triangular fibrocartilage complex (TFCC) injury is a tear of the cartilage and ligament complex on the ulnar side of the wrist, and a common cause of ulnar-sided wrist pain.

The TFCC stabilises the distal radioulnar joint (DRUJ) and transmits load between the ulnar carpus and the ulna. Tears are traumatic (Palmer class 1), typically after a fall on an outstretched hand or a forced rotation, or degenerative (Palmer class 2), often with positive ulnar variance.

TFCC abnormalities are frequent on MRI of wrists without symptoms, so decisions rest on symptoms and DRUJ stability, not on imaging alone.

The TFCC includes the articular disc, the dorsal and volar radioulnar ligaments (the main DRUJ stabilisers), the meniscal homologue, the ulnar collateral ligament and the extensor carpi ulnaris (ECU) subsheath. The radioulnar ligaments attach to the ulnar fovea and styloid. Only the periphery has a blood supply, about the outer 10% to 40% in a cadaver study, so peripheral tears can heal or be repaired and central tears cannot.

Palmer classification:

• •Class 1 (traumatic): 1A central perforation; 1B peripheral ulnar avulsion, which may involve the foveal attachment and cause DRUJ instability; 1C distal (volar ulnocarpal ligament) tear; 1D radial-sided avulsion from the sigmoid notch
• •Class 2 (degenerative, 2A to 2E): progressive ulnar impaction, from disc thinning through perforation and lunotriquetral ligament tear to ulnocarpal arthritis

Traumatic tears follow axial load with extension and pronation, distraction or forced rotation. Degenerative tears reflect repeated ulnocarpal loading, increased by positive ulnar variance, where the ulna is longer than the radius and the lunate impacts the disc in ulnar deviation.