Triquetral Fracture

Triquetral fractures are the second most common carpal fractures (after scaphoid fractures). Unlike the scaphoid, the triquetrum has a rich vascular supply.

Triquetral fractures can be classified based on the location of the fracture and severity of associated injuries.

• Type 1: Most common type of triquetral fracture. Isolated avulsion or shear fractures involving the dorsal cortex, usually seen following a hyperflexion injury. Considered benign fractures that heal well following immobilization. Best seen on the lateral view.
• Type 2: Less common. Comminuted fracture of the triquetral body. Considered more serious and seen in association with other carpal fractures.
• Type 3: Rare. Fracture of the volar aspect of the triquetrum. Associated with injury to perilunate ligaments. Best seen on posteroanterior views with radial deviation of the wrist.

The top patient presented following a hyperflexion injury. The frontal and oblique views failed to reveal a fracture. On the lateral view, we see a bony fragment at the dorsal aspect of the proximal row, consistent with a type 1 fracture. Another type 1 triquetral fracture is seen in the bottom image. This patient also had a comminuted distal right radius fracture, which is appreciated in this coned-down view as abnormal dorsal angulation of the distal radius.

Osteochondral fractures of the triquetrum have also been described, but are thought to be very rare. They are thought to be associated with subluxation or dislocation of the pisiform.

References

• Smith DK, Murray PM. Avulsion fractures of the volar aspect of triquetral bone of the wrist: a subtle sign of carpal ligament injury. AJR Am J Roentgenol. 1996 Mar;166(3):609-14.
• Suzuki T, Nakatsuchi Y, Tateiwa Y, Tsukada A, Yotsumoto N. Osteochondral fracture of the triquetrum: a case report. J Hand Surg Am. 2002 Jan;27(1):98-100.