In scaphoid fractures, which location has the highest risk of nonunion and avascular necrosis due to poor blood supply?

In scaphoid fractures, which location has the highest risk of nonunion and avascular necrosis due to poor blood supply?

• A. Waist
• B. Proximal Pole
• C. Distal Pole
• D. Middle

Answer: (B)

The key idea is how the scaphoid’s blood reaches the bone. The arterial supply enters mainly from the distal end and travels toward the proximal pole, so the proximal fragment relies on retrograde flow for its nourishment. If a fracture occurs at the proximal pole, this blood supply to that fragment is cut off or greatly diminished, making avascular necrosis very likely and healing slow or unlikely, which leads to nonunion. In contrast, the distal pole has better, more direct blood flow, and the waist (middle) region, while it can heal slowly if displaced or treated late, generally preserves more of its blood supply than the proximal pole. Therefore, the closest to the wrist with the poorest perfusion to the fragment is the proximal pole, explaining why it carries the highest risk of both nonunion and avascular necrosis.

The key idea is how the scaphoid’s blood reaches the bone. The arterial supply enters mainly from the distal end and travels toward the proximal pole, so the proximal fragment relies on retrograde flow for its nourishment. If a fracture occurs at the proximal pole, this blood supply to that fragment is cut off or greatly diminished, making avascular necrosis very likely and healing slow or unlikely, which leads to nonunion. In contrast, the distal pole has better, more direct blood flow, and the waist (middle) region, while it can heal slowly if displaced or treated late, generally preserves more of its blood supply than the proximal pole. Therefore, the closest to the wrist with the poorest perfusion to the fragment is the proximal pole, explaining why it carries the highest risk of both nonunion and avascular necrosis.