Fractures of The Scaphoid (Navicular)
The scaphoid is a small peanut-shaped bone that lies at the base of the thumb where it joins the wrist. Fractures of the scaphoid usually occur in younger patients after a fall on an outstretched hand. Pain and swelling are most pronounced in the “snuff box” at the base of the thumb. The great difficulties with scaphoid fractures is that many of them are non-displaced (e.g. a “hairline crack”) and are extremely difficult to detect on regular X-rays. Because of this, other studies (such as a CT scan or MRI) are sometimes necessary to diagnose these.
It is not uncommon for these fractures to be completely missed by the doctor who sees this patient immediately after the injury, even with adequate X-rays. Furthermore, these fractures have a lower rate of healing than most other fractures of the wrist. To make matters even worse, when these fractures go on to non-union (i.e. the bone fails to heal) they predictably result in development of arthritis of the wrist at a premature age. Since these injuries most often occur in young people, the arthritis develops at a time in their lives when they are most likely to experience loss of ability to work or participate in leisure activity due to the arthritis.
Nonsurgical (Cast Treatment) of Scaphoid Fracture
Because of the great potential for significant complications if the fracture goes on to non-union, every attempt is made to protect or stabilize the fracture. Cast treatment alone is reserved for only those fractures that are completely nondisplaced, and the cast may have to be worn for two, three, or even more months to get the bone to heal. Sometimes a bone stimulator (an electromagnetic or pulsed ultrasound generator) is prescribed to increase the chances of healing, especially in a fracture that is diagnosed late.
Example: 23-Year-Old Man, Scaphoid Fracture Treated With Cast And Bone Stimulator
- Left: X-ray at the time of injury. Notice how the fracture is nearly invisible
- Center: X-ray two weeks later. The fracture line is now obvious as the bone begins to heal
- Right: X-ray two months later, demonstrating nearly complete healing
Surgery for Scaphoid Fracture
Most scaphoid fractures that have any displacement whatsoever are treated by surgery because the odds of healing are much greater with this type of treatment. In this surgery, a special headless screw is placed across the bone using a small incision in the wrist. Once the screw is placed, most patients do not require a cast unless the fracture was very severe or if there are concerns about bone quality. The screw is countersunk and therefore does not protrude from the bone. It very seldom causes any irritation of the wrist or needs to be removed.
- Left: Preoperative X-ray showing a scaphoid fracture in a young man
- Right: Postoperative X-ray showing the scaphoid fixed with a bone screw
Due to its poor blood supply, even despite cast treatment, approximately 10% of scaphoid fractures fail to heal (a scaphoid nonunion). This predictably leads to altered wrist mechanics and eventually, arthritis of the wrist. If cast treatment of a scaphoid fracture fails, then bone graft (bone removed from another part of the body, transplanted to the scaphoid nonunion site) and screw fixation is the preferred method of treatment. The source of this bone may be the patient’s wrist (distal radius) or hip (iliac crest graft).
Example: 46-Year-Old Woman with Longstanding Scaphoid Nonunion Treated by Bone Graft from Distal Radius
- Left: Initial X-ray: scaphoid nonunion with large bone defect
- Center: X-ray 1 week after surgery
- Right: X-ray at 6 months after surgery showing complete healing