Scaphoid Fracture

Scaphoid fracture is the most common carpal fracture, typically from a fall on the outstretched hand (FOOSH) with the wrist extended, and occurs mostly in young adults and athletes.

The main risk is a missed diagnosis. The scaphoid's blood supply runs from distal to proximal, so waist and proximal pole fractures risk non-union and avascular necrosis (AVN), which can lead to scaphoid non-union advanced collapse (SNAC) arthritis. Suspect it in any wrist injury with scaphoid tenderness, even when radiographs are normal.

The scaphoid bridges the proximal and distal carpal rows. Its oblique position makes it vulnerable to axial load through the extended wrist. It has a proximal pole, a waist (the most common fracture site) and a distal pole.

The blood supply is retrograde. The dorsal carpal branch of the radial artery enters distally at the dorsal ridge and supplies about 70% to 80% of the bone, including the proximal pole. A fracture across the waist or proximal pole can cut off the proximal fragment, causing AVN and non-union.

Healing by site:

• •Distal pole: good blood supply; usually heals in a cast
• •Waist: healing depends mainly on displacement
• •Proximal pole: the highest risk of AVN and non-union