The scaphoid bone is located on the thumb side of your wrist, close to the lower arm bones. It is shaped like a cashew nut. The blood supply to the bone enters from the top, but most fractures occur in the middle or lower portion of the bone. This presents a problem because the blood supply cannot reach the injury to encourage rapid, adequate healing.

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 wrist. It's a common injury in sports and motor vehicle accidents. The angle at which the wrist hits the ground determines the injury. 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.

Symptoms
Most of the time, a broken bone is obvious. The area around the break may be painful, swollen or deformed. But sometimes a bone can break without your realizing it. That's usually what happens to the scaphoid bone in your wrist. Many people with a fractured scaphoid think they have a sprained wrist instead of a broken bone because there is no obvious deformity and very little swelling. Symptoms that may indicate a scaphoid fracture include pain and tenderness on the thumb side of the wrist; swelling on the back and thumb side of wrist; and marked tenderness to pressure on the "anatomical snuffbox," a triangular-shaped area on the side of the hand between two tendons that lead to the thumb.

Treatment
Treatment is determined by the fracture site, the degree of displacement, and any associated injuries. Most scaphoid fractures are treated with immobilization in either a cast that covers the lower arm, the wrist and the thumb or one that covers the full arm, wrist and thumb. Healing time can range from six weeks for fractures in the top portion to six months for fractures in the lower portion. Even with immediate cast immobilization, however, not all scaphoid fractures will heal properly. Surgical bone graft placement with internal fixation is usually recommended when the scaphoid fails to heal (non-union).