A 35-year-old man fell while snowboarding and injured his right wrist. He presents to the ED 2 days after the initial injury complaining of pain with movement and swelling over the wrist. He has pain with axial loading of the thumb, and pain with palpation over the anatomic snuffbox. An x-ray of the wrist is obtained (see Figure 13-3). Which of the following is TRUE?
Left untreated, a scaphoid fracture may develop avascular necrosis of the distal segment that may lead to severe arthritis.
The blood supply to the scaphoid is in the distal segment of bone, and flow from branches of the median and ulnar arteries may be compromised with a fracture and cause avascular necrosis of the proximal segment.
The risk of developing avascular necrosis increases, the more proximal, oblique, or displaced the fracture is.
A scaphoid fracture is considered unstable once there is a minimum of 3 mm of displacement.
Possible complications of untreated scaphoid fractures include avascular necrosis, degenerative arthritis, and carpal tunnel syndrome.
Two-thirds of the surface of the scaphoid is articular, and any compromise in blood flow can result in avascular necrosis and subsequent degenerative arthritis. The vascular supply to the scaphoid consists of small perforators from the radial artery, palmar, and superficial arteries. The blood supply enters through the distal segment of the scaphoid, and if it is disrupted by fracture, the proximal segment loses its blood supply and can develop avascular necrosis. Fractures are considered unstable with as little as 1 mm of displacement. Comminuted fractures and fractures with any component of rotational deformity are also considered unstable. Unstable fractures are much more likely to cause disruption to the blood flow. Therefore, early immobilization and operative intervention for unstable fractures are crucial.