Hook of hamate fracture. Persistent pain despite normal x-rays.

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Persistent wrist pain after a fall, despite normal x-rays, may point to a hook of hamate fracture. This case highlights when MRI or CT may be needed.

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Case

This 42-year-old male recreational football player presents with an eight-week history of hand and wrist pain following a fall onto his right-hand. He is found to have localised tenderness over the volar aspect of his wrist and mild discomfort with gripping activities.

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Findings

An x-ray series of the wrist was completed at the time of his injury and again several weeks later. These were normal. MR imaging shows a comminuted, displaced fracture through the top of the hook of the hamate separating a small 6mm bony fragment at the flexor retinaculum attachment. There is moderate associated localised bone oedema. The flexor retinaculuam is otherwise normal.

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Discussion

This player was diagnosed with a hook of hamate fracture. As the fracture fragment was very small, he was managed with a period of relative rest. He was able to run and play football within a few weeks of his injury. He had to avoid movements at work (like using a hammer) that aggravated his symptoms but reported a progressive improvement in his symptoms over a period of four months. At this point he was able to return to normal activities.

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Hook of hamate fractures are rare. In sport the classic mechanism is a direct blow to the volar aspect of the hand or wrist from a "duffed" golf swing, although any direct blow of the hand or wrist can cause this injury. A delayed diagnosis may lead to non-union, chronic grip pain, flexor tendon irritation and, less commonly, ulna nerve symptoms.

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The hook of the hamate lies outside the plan of standard wrist x-rays, making fractures difficult to identify on routine PA and lateral views. A specialised x-ray view (carpal tunnel view) may be used to document the injury. CT imaging can also be helpful. Management depends on the patient's symptoms, size or displacement of the fracture and patient demands. Many minimally displaced fractures can be managed non-surgically, while persistent symptoms, symptomatic non-union or high-demand athletes may benefit from surgical excision of the fragment.

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Persistent focal tenderness over the volar-ulnar wrist after trauma should prompt consideration of a hook of hamate fracture, even when standard wrist x-rays are normal. If symptoms persist despite normal x-rays, CT or MRI may be needed to establish the diagnosis.