The scaphoid bone is located on the thumb side of your wrist, close to the lower arm bones It is shaped like a cashew, which makes it hard to visualize on the xray. The reason scaphoid fractures have a hard time healing is due to the anatomy of the blood supply to the bone. Since the scaphoid is mostly covered in cartilage, there is a limited area for the arteries to enter the bone. In the scaphoid, the blood supply to the bone enters from the distal end, that is, the end toward your fingers. This can be a problem for healing, since most fractures occur in the middle or proximal portion of the bone. The blood supply to the proximal fragment, that is, the piece that is toward your elbow, may not have any blood supply. Without a blood supply, the bone cannot heal and that fragment may die.
Scaphoid fractures account for about 60 percent of all wrist (carpal) fractures. They usually occur in men between ages 20 and 40 years, and are less common in children or in older adults. The break usually occurs during a fall on the outstretched hand. It’s a common injury in sports and motor vehicle accidents. The angle at which the hand hits the ground determines the injury. The following is a very rough "rule of thumb": If the wrist is bent at a 90-degree angle or greater, the scaphoid bone will break; if the angle is less than 90 degrees, the lower arm bone (radius) will break.
Signs and symptoms include pain and tenderness on the thumb side of the wrist. Motion (gripping) may be painful. There may be swelling on back and thumb side of wrist. Pain may subside, then return as a deep, dull aching. Marked tenderness to pressure may exist on the "anatomical snuffbox," a triangular-shaped area on the side of the hand between two tendons that lead to the thumb.
The diagnosis is based on a history of trauma to the wrist (usually a fall or accident), a clinical exam that shows tenderness in the region of the scaphoid and a painful Watson test (a maneuver in which the wrist is moved back and forth, with the examiner's thumb on your scaphoid; it is just slightly painful), and xrays that show a fracture. Sometimes, the xray does not show a fracture. Usually, with a supportive history and clinical exam, the diagnosis will be made of a probable scaphoid fracture.
Treatment is determined by the fracture site, the degree of displacement, any associated injuries, and the patient's occupation and desires.
Most scaphoid fractures are treated with immobilization in a cast that immbolizes the elbow, wrist, and thumb, for six weeks, and then only the wrist and thumb for an additional six weeks. Healing time, however, can range from six weeks for fractures in the top portion (toward the fingers) to six months or longer for fractures in the lower portion (toward the wrist). The cast must be checked regularly to make sure that it fits properly and prevents movement. After the cast is removed, a rehabilitation program helps restore range of motion and strength.
Some fractures are displaced by 1 mm or so. These usually need surgical treatment. Scaphoid fractures that are accompanied by other injuries, usually a distal radius fracture, also need surgery. Also, with newer techniques, the risks of surgery are so low that some patients choose surgery, because it usually means the patient does not need to wear a cast at all, just a splint.This is particularly common when a proximal pole fracture exists, because of a high risk of nonunion.
So surgery for even a nondisplaced proximal pole fracture---as seen in the above x-ray--is often recommended. I have attached a recent article from the Journal of Hand Surgery that addresses risk factors for nonunion.
