Avascular necrosis after a displaced fracture of the waist of the scaphoid occurs because its arterial supply has which characteristic?
- A It enters distally on the dorsal ridge and passes retrograde toward the proximal pole ✓
- B It enters exclusively at the tubercle and runs proximally
- C It arises from branches of the ulnar artery entering the lunate fossa
- D It is supplied equally by two nutrient arteries entering mid-waist
Correct answer: A. It enters distally on the dorsal ridge and passes retrograde toward the proximal pole
Explanation
The scaphoid is supplied mainly by the radial artery via vessels entering at the distal pole and dorsal ridge. These branches course proximally, so a displaced waist fracture interrupts retrograde flow and starves the proximal fragment, causing avascular necrosis and non-union. This retrograde supply also explains why the proximal pole shows increased sclerosis and collapse while distal fragments stay vascular.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.