Triangular fibrocartilage complex.

The TFCC is located on the ulnar aspect of the wrist joint between the ulna and the lunate and triquetrum of the proximal carpal row. It has an elongated triangular shape with the apex pointing at the radius  and consists of the following as described in the next images.

T = triquetrum, L = lunatum, H = hamatum, R = radius, U = ulna, 1 = ECU tendon and sheath, 2 = ulnar carpal collateral ligament,  3= ulnomeniscal homologue (UMH), 4 = triangular fibrocartilage complex (TFCC), Arrow = prestyloid recess.

Distal radioulnar joint instability associated with distal ulnar marrow edema and tear of the ulnar attachment of TFCC allow some fluid to track proximal to the ligament.

Diagnosis: TFCC tear type 1b and DRUJ instability

Perforation of the radial portion of the discus with fluid in the gap.

Case Discussion

This would classify as a Palmer Ia lesion, which does not heal spontaneously.

Bone bruise and dorsal displacement of the ulnar head of about 10 mm. Effusion in the distal RU joint. Focal bleeding into the ulnar insertion of the discus with avulsion of the ulnar styloid process.

Marked dorsal displacement of the ulnar head, volar capsular haematoma and effusion of the RU joint indicates rupture of the volar radioulnar ligament.


Reference