A 24-year-old man fell on an outstretched hand. Anatomical snuffbox tenderness was present but initial radiographs were normal. He was not immobilised and returns 6 weeks later with persistent wrist pain. MRI shows non-union of the waist of scaphoid with sclerosis of the proximal pole. The avascular necrosis occurred because:
- A The scaphoid receives its entire arterial supply from the volar branch entering the distal pole, flowing retrograde ✓
- B The scaphoid has a dual supply from both radial and ulnar arteries entering the proximal pole
- C The lunate compresses the nutrient artery during wrist extension
- D The dorsal branch supplying the proximal pole enters through the waist and is easily torn
Correct answer: A. The scaphoid receives its entire arterial supply from the volar branch entering the distal pole, flowing retrograde
Explanation
The scaphoid is supplied mainly by branches of the radial artery that enter the distal pole and waist, with blood flowing retrograde to the proximal pole. A waist fracture therefore devascularises the proximal fragment, causing AVN and non-union. Option B is wrong because there is no dual supply protecting the proximal pole, which is exactly why this fracture behaves differently from most carpal bones.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.