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Fall on an outstretched hand
A 22-year-old falls off a skateboard onto an outstretched hand with the wrist dorsiflexed. She has pain on the radial side of the wrist.
Step 1 of 4
Which examination finding most suggests a scaphoid fracture?
Correct answer: B
The scaphoid forms the floor of the anatomical snuffbox. Snuffbox and scaphoid tubercle tenderness, and pain on axial loading of the thumb, suggest a fracture. It is the most commonly fractured carpal bone.
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B
The scaphoid forms the floor of the anatomical snuffbox. Snuffbox and scaphoid tubercle tenderness, and pain on axial loading of the thumb, suggest a fracture. It is the most commonly fractured carpal bone.
Step 2 of 4
Radiographs, including a dedicated scaphoid view, are normal.
What is the most appropriate next step?
Correct answer: E
Scaphoid fractures can be radiographically occult at first. With clinical suspicion, immobilize in a thumb spica splint and repeat imaging in 10–14 days, or get an MRI (or CT) early.
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E
Scaphoid fractures can be radiographically occult at first. With clinical suspicion, immobilize in a thumb spica splint and repeat imaging in 10–14 days, or get an MRI (or CT) early.
Step 3 of 4
Which test is the most sensitive for an occult scaphoid fracture?
Correct answer: A
MRI is the most sensitive modality (marrow edema, fracture line) and also assesses proximal pole viability.
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A
MRI is the most sensitive modality (marrow edema, fracture line) and also assesses proximal pole viability.
Step 4 of 4
Why does a fracture through the scaphoid waist put the proximal pole at risk of avascular necrosis?
Correct answer: C
The scaphoid's blood supply is retrograde: vessels from the radial artery enter at the waist and distal pole. A waist fracture can cut off the proximal pole, causing avascular necrosis and nonunion.
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C
The scaphoid's blood supply is retrograde: vessels from the radial artery enter at the waist and distal pole. A waist fracture can cut off the proximal pole, causing avascular necrosis and nonunion.
Key points
- Snuffbox tenderness + normal X-ray → thumb spica splint and repeat imaging (or MRI).
- Retrograde blood supply → proximal pole AVN and nonunion.
Study: Scaphoid, Radial artery, Wrist joint