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What is the diagnosis?

Triquetral avulsion fracture, dorsal chip fracture

• Pearl: Carpal fractures account for approximately 10 percent of all hand fractures. Triquetral fractures represent approximately 15-30 percent of all carpal fractures [1,2]. The dorsal chip fracture is the most common fracture of the triquetrum. The second most common is the triquetral body fracture which is typically associated with a perilunate fracture dislocation and a higher mechanism of injury [3, 4].
  
  

Image 2. Lateral XR of triquetral fracture with arrow pointing at dorsal chip. Author's own image and annotation

What is the mechanism of injury?

The mechanism of injury is typically a fall on an outstretched hand while in wrist extension and ulnar deviation [4, 5, 6].

• Pearl: Rather than direct trauma, the cause of triquetral fractures is the chisel action of the hamate striking the triquetrum causing a chip [7]. 

What physical exam findings are expected?

Physical exam findings are typically tenderness over the dorsum of the wrist on the ulnar side of the carpal bones. Ecchymosis and edema can be present as well. Some decreased range of motion of the wrist can be expected [4, 5, 6].

Which imaging modalities can be used?

X-ray (XR) is the initial imaging modality of choice. There is a high rate of occult fractures based on XR images. In the event of a negative XR, a CT scan should be pursued since it has a better sensitivity [8].

• Pearl: There is no single best view on XR imaging to evaluate triquetral fractures. Combining, AP, lateral and oblique views will typically provide adequate evaluation via radiographs [6]. 

What is the management in the ED

Chip fractures can be treated with immobilization in a volar splint of the wrist.  Subsequently patients are transitioned to a short arm cast in a week. At 4 weeks patients are placed into a removable brace with the goal to be out of immobilization by 8 weeks [6]. 

When should you consult Orthopedics?

There is no indication for surgical intervention for dorsal chip fractures.  The risk for post-traumatic instability is very low. Orthopedics typically does not need to be consulted for these fractures, as they can be managed conservatively with a volar splint. Orthopedics should be involved in the setting of a displaced transverse body fracture as these are sometimes managed surgically [7].