A 36-Year-Old Man with Wrist Pain After a Traumatic Impact

Diagnosis

The AP view of this right hand series shows a displaced coronal fracture of the hamate located on the dorsal aspect of the distal carpal row.  The oblique view reveals dorsal metacarpal dislocation of the 5^th metacarpal.  These views also show an overlap of the 4^th and 5^th metacarpals with the hamate which supports the dislocation component of this injury.

The correct diagnosis is a coronal fracture of the body of the hamate with dorsal metacarpal dislocation of the 5^th and likely also the 4^th metacarpal—an uncommon injury that accounts for <2% of all carpal bone fractures.

Learnings/What to Look for

• The typical mechanism of injury for this diagnosis is direct impact against a hard surface with a clenched fist in ulnar deviation and palmar flexion (flexion produces metacarpal dislocations)
• The hamate fracture may be associated with 4th or 5th metacarpal base fractures or dislocations which are present in approximately 15% of cases
• Hamatometacarpal fracture-dislocation may be missed at initial presentation, in up to 71% in some studies
• Routine radiographic evaluation with only anteroposterior and lateral views of the wrist may not reveal the lesion, being only visible with an oblique view of 30° of forearm pronation

Pearls for Urgent Care Management and Transfer

• A high-resolution CT scan of the wrist is considered mandatory to completely evaluate these injuries and determine appropriate treatment
• Open reduction and internal fixation is likely to be required

Acknowledgment: Images and case presented by Experity Teleradiology (www.experityhealth.com/teleradiology).

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