A scaphoid fracture describes an injury that breaks the scaphoid bone in the wrist.
The wrist joint is formed by the articulation of the radius and ulna bones of the forearm with three of the eight carpal bones at the base of the hand. These carpal bones are arranged in two rows, one nearer the hand and one nearer the forearm. The boat-shaped scaphoid bone links the two rows and is particularly vulnerable to injury. It is in fact the most commonly broken carpal bone in the wrist. It is found is on the thumb side of the wrist and articulates with the distal end of the radius, helping to limit the degree of movement of the wrist.
The most common cause of a scaphoid fracture is a fall onto the palm of an outstretched hand, although any trauma producing sufficient force can break the bone. The fracture can happen in isolation but often the injury involves a fracture of the radius as well. Young men between the ages of 15 and 30 are most likely to suffer this type of injury.
A sprained wrist that does not include a fracture is very rare, so if you are experiencing any of the symptoms listed above that do not go away within a day or two, you should seek medical advice. Often, due to the way that symptoms diminish, people do not realize that they have a scaphoid fracture.
- Pain, ranging from relatively mild to severe, felt at the base of the thumb at the moment of injury; possibly worse when trying to grip or squeeze, but often diminishing with time
- Swelling of the base of the thumb, often minimal
- Possible deformity of the wrist, but unusual
Your doctor will ask you for your medical history and the details of any previous injury to your wrist. You will be asked about the circumstances of your current injury and the type and severity of your symptoms. Your wrist will be physically examined and compared with the uninjured wrist. The doctor may test for tenderness by pressing on the hollow at the base of the thumb, the so-called ‘snuffbox’. This is not a specific test for a scaphoid fracture, but pain elicited by pressing on this point increases the suspicion of a fracture. Pain produced by pressing on the bony protuberance on the inner side of the wrist while extending the wrist is a more specific test that your doctor will likely perform.
X-rays will be taken to look for a possible fracture and to assess the degree of bone displacement if a fracture is present. Sometimes a scaphoid fracture is not immediately visible on an X-ray, especially if there is no bone displacement. In this case your doctor may place your wrist in a splint for a week or two and then have more X-rays taken. An MRI (magnetic resonance imaging) or a bone scan may be taken as these often show a fracture that was not revealed on the initial X-rays. MRI scans can also show any damage to the soft tissues of the wrist.
The scaphoid bone has varying degrees of blood supply, which affects the ability of the bone to heal. Complete immobilization of the wrist is necessary as a broken scaphoid is unstable and even a non-displaced fracture may shift later, making bone union less likely.
Non-displaced fractures closer to the thumb will normally heal well with conservative (non-surgical) treatment. Your arm and hand will be placed in a thumb spica that will probably begin below the elbow. It may, but will probably not, cover the lower part of the thumb. You will need to remain in the cast for at least six to ten weeks. Regular X-rays, and possibly CT (computerized tomography) scans, are likely to be taken to monitor the healing process.
If the fracture is nearer the forearm where the scaphoid bone has a poor blood supply, the cast placed on your arm will probably reach beyond the elbow and will also include the thumb. The length of time spent in the cast will be longer. There is a risk that, because of the lack of a good blood supply, a fracture in this area may cause part of the bone to die. For this reason, or if the fracture is displaced, surgical repair might be the best treatment. The goal of surgery would be to fix the bone fragments in their correct position using orthopedic fixing devices such as pins, wires or screws. Occasionally it may be necessary to take some bone tissue from another part of your body, usually from your forearm or, sometimes, your hip to use as a bone graft. This is normally only needed if the scaphoid has been broken into more than two pieces. The bone graft tissue is placed around the fractures in order to stimulate new bone growth.
After surgery, and even if you have not had surgery, the cast or splint will need to stay in place until the bone has completely healed, which may take six months or even longer. During this time you will need to avoid any activities that might displace the healing bone fragments.
With such an extended period in a cast or splint, and particularly if you had to have surgery, your wrist and fingers will become stiff. You will need to keep moving your fingers throughout the healing period and, when the cast is removed and your doctor or physical therapist gives permission, you will need to do range of motion and strengthening exercises to rehabilitate the wrist. You will be given a graduated series of exercises to do. It is very important to have physical therapy in order to minimize what can be a degree of permanent loss of motion and function in the wrist.
Because of the variable blood supply to the scaphoid even a treated fracture may not heal together properly. The resultant abnormal movement of the wrist may lead to arthritis. Avascular necrosis, or death of part of the bone due to inadequate blood supply, may also lead to arthritis. Further surgery can be attempted in order to improve the condition of the bone and enhance the blood supply.