Morphology of the Ulnar Insertion of the Triangular Fibrocartilage Complex and Related Osseous Landmarks

In triangular fibrocartilage complex (TFCC) injuries, a foveal tear of the radioulnar ligament often requires surgery. Previous studies have suggested that surgeons should attach the TFCC to the center of the fovea. The TFCC and its insertion points are small structures, and few studies have reported details of the foveal insertion. This study aimed to clarify the morphology of the ulnar insertion of the TFCC and related osseous landmarks with 3-dimensional imaging.

This study used 26 formalin-fixed cadavers. At the ulna, the TFCC was inserted from the fovea to the middle part of the ulnar styloid. After gross observation of the TFCC, the ulnar insertion was outlined using a 1.0-mm drill. We then created 3-dimensional images of the ulna using computed tomography and marked (with software) an outline of the foveal insertion of the TFCC. We measured the area and the long and short diameters of the TFCC insertion.

The area of the TFCC insertion was 34 mm² and positively correlated with the height of the ulnar styloid and the area of the ulnar head. The TFCC's highest point was 58% of the ulnar styloid height. The center of the TFCC insertion was 1.3 mm ulnar and 0.6 mm dorsal from the lowest point of the ulnar surface.

The center of the TFCC insertion was slightly ulnar of the lowest point of the ulnar surface. This study revealed the center, the area, and the osseous relation of the ulnar insertion of the TFCC.

When surgeons repair a TFCC foveal tear, they can find the anatomical center of the ulnar insertion efficiently and easily based on its osseous relationship.