The scaphoid is one of the small bones in the wrist. It is the wrist bone that is most likely to break.

The scaphoid is located on the thumb side of the wrist, in the area where the wrist bends.

The scaphoid can be identified more easily when the thumb is held in a "hitch hiking" position. The scaphoid is at the base of the depression made by the thumb tendons. Pain or tenderness in this area can be a sign that the scaphoid is injured.

A fracture of the scaphoid usually happens from a fall on an outstretched hand, with the weight landing on the palm. The end of one of the forearm bones (the radius) may also break in this type of fall, depending on the position of the hand on landing. Pain and swelling in the wrist will usually cause a person with a scaphoid fracture to see a doctor.

Fractures of the scaphoid occur in people of all ages, including children. The injury often happens during sports activities or a motor vehicle accident. Men aged 20 to 30 years are most likely to experience this injury.

There are no specific risks or diseases that increase the chance of having a scaphoid fracture. Some studies have shown that use of wrist guards during activities like inline skating and snowboarding can decrease the chance of breaking a bone around the wrist.

Unless the wrist is deformed, it might not be obvious that the scaphoid bone is broken. Sometimes, it might seem to be just a sprained wrist.

It is important to see a doctor if there is pain on the thumb side of the wrist that starts after a fall or accident and does not go away within a few days.

Scaphoid fractures usually cause pain in the base of the thumb, with swelling in the same area. The pain may be severe when the thumb or wrist is moved or the hand grips anything. In some cases, the pain is not severe, and may be mistaken for a sprain.

X-rays will be used to assess the bone. Sometimes, a broken scaphoid does not show up on an X-ray right away. If this is the case, the wrist might be put in a splint for a week or two. A new X-ray will be taken to see if the fracture will become visible. The splint should be worn during this waiting period, and heavy lifting should be avoided.

An MRI (magnetic resonance image) may be taken to visualize the bones and soft tissues. This sometimes shows a fracture of the scaphoid before it can be seen on an X-ray.

A bone that fails to heal is called a nonunion. Nonunions are more common after scaphoid fractures because blood supply to the scaphoid bone is poor. Blood supply to the bone is very important in its healing. Bones need blood to carry oxygen and nutrients to the site of the fracture.

When the scaphoid is broken, especially when the fragments have moved apart (displaced), the blood supply to those fragments may be disrupted. Sometimes, the blood supply to one of the fragments is so poor that the piece does not get enough nutrients and the cells in that fragment die. This is called avascular necrosis.

Over time, nonunion and avascular necrosis of the scaphoid can lead to arthritis of the wrist. Symptoms of arthritis in the wrist that results from scaphoid nonunion or avascular necrosis include:

• Aching in the wrist
• Decreased range of motion of the wrist
• Pain with activities such as lifting or gripping

If X-rays show arthritis in the wrist as a result of an old break in the scaphoid, treatment focuses on improving the symptoms of arthritis. At first, this may include taking anti-inflammatory medicine and wearing a splint when the wrist is painful. Sometimes, the doctor may inject a steroid into the wrist to help to lessen wrist pain.

If this does not work, surgery may be recommended. Many types of operations can be performed for wrist arthritis.

A cast or splint will need to be worn while the scaphoid fracture is healing. This may be for as long as six months. During this period of healing,

• Avoid heavy lifting, carrying, pushing, pulling or throwing with the injured arm
• Do not participate in contact sports
• Do not climb ladders or trees
• Avoid activities with a risk of falling onto hand (for example, inline skating, jumping on a trampoline)

Some people have stiffness in the wrist after scaphoid fractures. This is more common when a cast was needed for a long time or when surgery was done through a long incision. Hand therapy may be recommended to help regain the motion and strength in the wrist. Even with therapy, some people do not recover the same motion and strength in their wrists that they had before the injury.

Some orthopaedists are placing a screw in the scaphoid through a very small incision--about one-fourth to one-half inch. This may decrease the chances of long-term stiffness in the wrist by decreasing the time that a full-time cast needs to be worn. This is done using a special X-ray machine during surgery to help guide the placement of the screw. Some surgeons use this method even when the fragments of the scaphoid are out of place. By looking directly at the scaphoid with a tiny camera (an arthroscope), the surgeon can tell when the fragments are lined up.

There is a lot of research being done about the best way to treat fractures of the scaphoid that are not healing well. Some of this research looks at different types of bone graft, including vascularized grafts. New types of manufactured bone graft with special bone cell components to increase healing are now sometimes used.