June 24, 2010

Hook of Hamate Fracture

Figure 1: Frontal radiograph of the right wrist shows no apparent fracture. In retrospect, there may be slight indistinctness of the "eye" of the hamate hook.
Figure 2: Axial CT image at the level of the hamate shows a nondisplace fracture near the base of the hamate hook (arrow).

  • Uncommon fracture that is easily missed on radiography
  • Hook of hamate fracture is more common than fracture of the hamate body
  • Direct blow to the hook, or avulsion of transverse carpal ligament and pisohamate ligament
  • Presenting with pain on ulnar side of the palm aggravated by grasp, point tenderness over the hook at 1 cm distal and radial to the pisiform
  • Best seen on carpal tunnel view (radiography) or CT
  • If displaced and untreated, avascular necrosis and nonunion may occur.

Imaging Features
  • On frontal radiograph, there is absence or indistinctness of the "eye" of hamate (oval, dense cortical ring shadow over the hamate)
  • On CT scan, the fracture line is apparent at the hook best seen on axial images. It can involve the tip or the base of the hook

Singh AK, Kaewlai R. Extremity Trauma. In: Soto and Lucey's Emergency Radiology the Requisites, 2008.

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