Case 12 - Triquetral Fracture

Triquetral fractures are the second most common carpal bone fracture, often occurring along the dorsal aspect of the carpal bones. While there are multiple mechanisms for the method of injury, the most common method is impaction from the ulnar styloid, which acts as a chisel, along the dorsal cortex of the triquetrum.  Dorsal avulsion injuries are best visualized on the lateral radiograph, as seen in this case, as a result of the strong dorsal ligaments avulsing off the dorsal cortex.

Case courtesy of Dr. Matt Skalski

One of my favorite signs in all of radiology is the "Pooping Duck Sign," which is present on the lateral radiograph. The duck is the composed of the superimposition of the Scaphoid and the Lunate bones, while the 'poop' is the avulsed bony fragment of the triquetrum.

Here is a normal lateral radiograph of the wrist with the Pooping Duck sign below.

Courtesy of Dr. Michael L. Richardson, M.D.

Courtesy of Dr. Michael L. Richardson, M.D.

Image Courtesy of Radiology Tips (http://radiologytips.com/modality/radiography/pooping-duck/)

Nearly all of these fractures are treated non operatively; rarely is any surgery required.  As an aside, the skeletal anatomy website by Dr. Richardson is extremely helpful and one I recommend to add to your armamentarium as a quick resource for bony anatomy you might need throughout training.


References:

Case courtesy of Dr Matt Skalski, https://radiopaedia.org/.  From the case: https://radiopaedia.org/cases/57109

Radiographic Skeletal Anatomy by Michael L. Richardson, M.D. at the University of Washington:
http://uwmsk.org/RadAnatomy.html

Radiology Tips:
http://radiologytips.com