Dorsal fractures of the triquetrum-avulsion or compression fractures?

In 76 wrists, which had a dorsal fracture of the os triquetrum, the mean size of the ulnar styloid process was radiologically measured and found to be significantly larger (p less than 0.0001) that those in a control group of 100 noninjured hands. This finding supports the view that such injuries are not avulsions, as they are assumed to be, but are the product of a chisel action of a powerful ulnar styloid process on the dorsum of the triquetrum during strong dorsiflexion and ulnar deviation. In accordance, persons with a long styloid process have an increased chance of this kind of injury.