The scaphoid (or carpal navicular) is one of the eight small bones of the wrist joint. This bone, shaped similar to that of a cashew nut or kidney bean, is located between the base of the thumb and the radius bone of the forearm. The scaphoid coordinates the motion and position of all of the other wrist bones. It is key to the correct functioning of the wrist.
The most common injury of the scaphoid is a fracture (break), usually caused when a person falls with the hand stretched out to brace him or herself (a natural reaction). This is a frequent injury among snowboarders and active children who participate in sports.
Scaphoid fractures are quite common, but they can be difficult to detect. Unlike breaks in the long bones that connect to the wrist (such as the radius), a broken scaphoid is unlikely to display a visible, misshapen deformity in the wrist. The area around the scaphoid may not be noticeably swollen, and the fracture does not always cause severe pain.
For these reasons, this injury is often ignored or overlooked, and this can have significant consequences for future health. People who fracture the scaphoid often assume they have only sprained the wrist, since the symptoms are similar.
The most common symptoms are:
If you experience any of the above symptoms after a fall or traumatic injury to the hand or upper arm, you should consult an orthopedist or sports medicine doctor with expertise in hand injuries. He or she will first conduct a a physical examination. However, despite having very focused, orthopedic training, even the best hand doctor or surgeon will usually rely on X-rays or, in some cases, a CT scan or MRI imaging to confirm the diagnosis.
It is important get the right treatment. Otherwise, you risk improper healing and future problems like painful arthritis. A scaphoid fracture that is correctly treated soon after the injury will take about 12 weeks to heel. But an untreated fracture may take as long as six months to recover from. Untreated patients will also usually experience long-term problems moving their wrist or other complications (see below).
The most common treatment is to put the wrist in a long-arm cast that extends from the thumb to just below the elbow.
A scaphoid fracture can lead to wrist osteoarthritis, especially if the fracture is untreated and does not heal correctly. This is called “nonunion.” Severe cases of this kind of osteoarthritis can lead to an incorrect alignment of wrist bones in what is called scaphoid nonunion advanced collapse (SNAC).
Another type of injury which can accompany a scaphoid fracture or occur on its own is a rupture (tear) of the scapholunate ligament. This ligament connects the scaphoid with its neighbor, the lunate bone (also known as the semilunar bone). An undetected and untreated torn scapholunate ligament can also lead to osteoarthritis of the wrist. This can advance to become what is called scapholunate advanced collapse (SLAC). Like SNAC, SLAC is an incorrect alignment of the scaphoid and one or more of the other small bones of the wrist due. Unlike SNAC, the malalignment is caused only by the deterioration of soft tissues, rather than by bone nonunion.
Severe cases of SLAC or SNAC may require surgery to reduce pain or restore partial or full function of the wrist.
Learn more and find HSS doctors who treat scaphoid injuries below.