The scaphoid is supplied retrogradely from distal to proximal by the radial artery
Mnemonic
“Retrograde, entering distally”: the scaphoid is supplied mainly by the dorsal carpal branch of the radial artery, entering through the distal pole and dorsal ridge, and running back proximally within the bone.
“The further proximal the fracture, the worse the blood supply.”
- Distal pole fractures heal well
- Waist fractures, the commonest at about 70 per cent, have a moderate risk
- Proximal pole fractures have up to a 30 per cent risk of avascular necrosis and non-union
The talus and the femoral head share the same retrograde arrangement and the same vulnerability, which is worth remembering as a group.
Clinically: fall on the outstretched hand, snuffbox tenderness, pain on axial compression of the thumb. The initial radiograph is normal in up to 25 per cent, so the wrist is immobilised and reimaged, or MRI is obtained.
Untreated non-union leads to scaphoid non-union advanced collapse (SNAC wrist).
Expansion
- The scaphoid is supplied mainly by the dorsal carpal branch of the radial artery
- Vessels enter near the distal pole and run retrograde towards the proximal pole
- A fracture through the waist therefore threatens the blood supply to the proximal fragment, risking avascular necrosis and non-union
This is why snuffbox tenderness is treated as a scaphoid fracture until proven otherwise.