A 22-year-old man falls on an outstretched hand and has tenderness in the anatomical snuffbox. The initial radiographs are normal. The reason this suspected fracture carries a high risk of avascular necrosis is:

• A Its blood supply enters the proximal pole and flows distally
• B Its blood supply enters the distal pole and flows proximally in a retrograde manner ✓
• C It receives its entire supply from the ulnar artery
• D It has no periosteal blood supply whatsoever

Explanation

The scaphoid is supplied by branches of the radial artery that enter predominantly through the distal pole and dorsal ridge, with the supply running retrograde toward the proximal pole. A waist or proximal pole fracture therefore leaves the proximal fragment devascularised, producing avascular necrosis and non-union. Because early films may be normal, suspected scaphoid injury is immobilised and reimaged or assessed by MRI.

Reference: Apley's System of Orthopaedics and Fractures, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.