Scaphoid fracture

The scaphoid is one of eight small wrist bones, sitting at the base of your thumb. It's the most commonly broken wrist bone, almost always from falling onto an outstretched hand. Two things make it tricky. First, the fracture often doesn't show up on X-rays for the first week or two, so it gets missed at the initial visit. Second, the blood supply enters the bone backwards — flowing from the lower end up to the upper end — so the upper part can lose its blood supply if the fracture interrupts that flow. When the bone loses its blood supply and dies, that's called avascular necrosis.

The classic clue is tenderness in the small hollow at the base of your thumb on the back of your wrist — the anatomic snuffbox — after a fall onto an outstretched hand.

Initial X-rays often look normal even when the bone is broken — early scaphoid fractures are notoriously invisible on standard X-ray. An early MRI is the most sensitive test for catching it acutely. A CT scan is best for measuring how far the fragments have shifted, locating the fracture along the bone (waist vs. upper pole), and — in fractures that didn't heal correctly — checking for avascular necrosis or non-union.

Surgery is the answer when the fracture has shifted (more than about 1 mm), when it sits in the upper part of the bone (where the blood supply is most fragile), when an athlete needs to get back to sport faster than a cast allows, or when a previous fracture didn't heal. The repair places a small screw down the length of the bone to compress the fracture together.

External patient-education references and related OSI pages for additional background:

• Britannica — Bone disease (fractures)
• Britannica — Hand (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language