Ulnar styloid fracture

Ulnar styloid fractures occur in association with ~60% of distal radius fractures. Most of these are small avulsion fractures involving the tip of the ulnar styloid.

Pathology

Usually, this kind of fracture occurs as the result of a fall on an outstretched arm and is often associated with a distal radius fracture.

Radiographic features

The fracture is easy to recognize on plain film. Sometimes the fractures may not seem very apparent on x-ray if there is no displacement.

In the pediatric and adolescent forearm, it should be remembered that in very rare situations the ulnar styloid can arise from a separate ossification center, but mostly separation is caused by injury.

Treatment and prognosis

It is believed that lack of union of these avulsion fractures does not significantly affect late functional results. Fractures at the very base of the ulnar styloid can cause instability of the distal radioulnar joint (DRUJ) and disruption of the triangular fibrocartilage complex (TFCC) insertion at the ulnar fovea. It is argued that these injuries, therefore, need open stabilization.

Differential diagnosis

• persistent ulnar styloid or other accessory ossicles of the wrist that occur around the distal ulna
• pathological fracture e.g. erosive arthropathy such as gout