The high incidence of avascular necrosis after a displaced fracture of the waist of the scaphoid is explained by:
- A Its blood supply enters mainly through the distal pole and flows retrograde toward the proximal pole ✓
- B The scaphoid is covered entirely by articular cartilage with no soft tissue attachment
- C The scaphoid receives its supply solely from the anterior interosseous artery
- D Synovial fluid dissolves any forming callus across the fracture
Correct answer: A. Its blood supply enters mainly through the distal pole and flows retrograde toward the proximal pole
Explanation
The scaphoid is supplied largely by branches of the radial artery entering the dorsal ridge at the distal pole, with intraosseous flow running retrograde to the proximal pole. B waist fracture therefore devascularises the proximal fragment, giving avascular necrosis and non-union rates up to 30 percent in displaced fractures. Option B is incorrect because ligamentous and capsular attachments carry the vessels. Synovial fluid does inhibit external callus but is not the cause of AVN.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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