There are two rows of small wrist bones that move together and let our wrists take a variety of positions and movements (Figure 1). One of these eight bones is the scaphoid, and it links two rows together and contributes to both the stability of the wrist and coordination of its motion.
The position and role of the scaphoid makes it vulnerable to injury. Since it has a delicate supply of blood, the scaphoid may not heal properly if it is broken or fractured. Any time a scaphoid fracture doesn't heal properly, it is called a scaphoid non-union, and that condition can result in wrist arthritis or loss of motion in the wrist.
Scaphoid non-union usually occurs in people who have fallen on their wrist or who have a history of wrist injury. There is usually a pain that runs along the thumb side of the wrist, and the wrist may have lost some mobility, especially if it is extended. X-rays are used to confirm scaphoid fractures and non-unions, and special x-ray tests are often used to decide how to best treat the condition. If it is thought that the scaphoid has collapsed and become bent, a CT scan can reveal that condition, also known as a "humpback" deformity.
If left untreated, scaphoid non-unions may develop into a condition known as avascular necrosis, which results when the flow of blood to the scaphoid is lost and part of the bone dies. This, in turn, can lead to collapse of the scaphoid and it's becoming fragmented, thereby making treatment and repair much more challenging. This condition can be checked with an MRI.
The treatment of scaphoid non-union depends on a few things. If a fracture to the bone hasn't healed properly, a series of further degeneration can be expected, although the time it takes for these to show up varies. The end result, collapse of the scaphoid, changes how the wrist operates and results in loss of motion and arthritis.
There are different treatments, depending on when treatment of the condition begins and the extent of injury. If there is no arthritis, wrist surgery to restore the scaphoid's alignment and heal the bone is the first choice. This procedure requires the addition of pins or screws to hold the bone in place as well as a bone graft.
If avascular necrosis is present, the death of part of the scaphoid requires special treatment. This condition is difficult to treat, but recent advantages using bone grafts with an attached blood vessel to keep the bone supplied with blood have improved treatment of this condition.
In spite of the best wrist surgery, scaphoid non-union may not respond to treatment and may never heal.
If arthritis in the wrist is present, or earlier attempts to reconstruct the condition haven't worked, wrist surgery cannot be used to heal the bone. Surgery may, however, be used to reduce the pain or keep the wrist functioning. The extent of the arthritis determines what can be accomplished through surgery. A radial styloidectomy, a procedure to remove a part of the arthritic bone, may be used to save wrist motion. Other treatments may include partially fusing the wrist bones or a proximal row carpectomy, which removes the proximal row of wrist bones. A complete wrist fusion may be the only possible treatment if the arthritis is more widespread.