Definition
Most of the time, a broken bone is obvious. The area
around the break may be painful, swollen or deformed. But sometimes
a bone can break without your realizing it. That’s usually what
happens to the scaphoid (skaf'-oyd) bone in your wrist. Many people
with a fractured scaphoid think they have a sprained wrist instead
of a broken bone because there is no obvious deformity and very
little swelling.
The scaphoid bone is located on the thumb side of your wrist,
close to the lower arm bones. It is shaped like a cashew nut. The
blood supply to the bone enters from the top, but most fractures
occur in the middle or lower portion of the bone. This presents a
problem because the blood supply cannot reach the injury to
encourage rapid, adequate healing.
Who’s at risk?
Scaphoid fractures account for about 60 percent of all wrist
(carpal) fractures. They usually occur in men between ages 20 and 40
years, and are less common in children or in older adults. The break
usually occurs during a fall on the outstretched wrist. It’s a
common injury in sports and motor vehicle accidents. The angle at
which the wrist hits the ground determines the injury. If the wrist
is bent at a 90-degree angle or greater, the scaphoid bone will
break; if the angle is less than 90 degrees, the lower arm bone
(radius) will break.
Signs and symptoms
- Pain and tenderness on the thumb side of the wrist.
- Motion (gripping) may be painful.
- May be some swelling on back and thumb side of wrist.
- Pain may subside, then return as a deep, dull aching.
- Marked tenderness to pressure on the "anatomical snuffbox," a
triangular-shaped area on the side of the hand between two tendons
that lead to the thumb.
Diagnosis
If you’ve fallen and think you’ve sprained your wrist, see your
doctor as soon as possible. Your physician will ask you to describe
what happened, examine your hand and wrist, and order X-rays of the
area. Unless the fracture is displaced (the bone ends no longer
touch each other), it may be difficult to see a scaphoid fracture on
the first set of X-rays. Even if the initial X-rays do not show a
scaphoid fracture, your physician may immobilize your wrist in a
cast or splint for a week or so.
Radiographs.
Routine radiographs of the scaphoid include anteroposterior (AP),
lateral, and oblique (45° from horizontal) views. The AP view is
done with the fist mildly clenched and the wrist in ulnar deviation.
(An AP view with a tightly clenched fist and ulnar deviation can be
ordered to screen for ligament injury.) The lateral view is done
with the wrist in neutral position. When the scaphoid is injured in
the normal wrist, the lateral view shows a line of concentric arcs
formed by the distal radius, lunate, and capitate. The longitudinal
axis of these bones should be collinear. Disruption of this
alignment suggests a ligament injury or dislocation, displacement,
or angulation of a fracture.
If radiographs are negative despite clinical suspicion of a
scaphoid fracture, the patient's wrist is immobilized and
radiographs are repeated in 2 weeks. If plain films continue to be
negative but clinical suspicion remains, further imaging should be
pursued. Bone scan and computed tomography have been used with about
equal accuracy to detect occult fractures. Polytomography and
magnetic resonance imaging (MRI) can also be used though they are
more expensive. MRI can demonstrate much more anatomy and, because
of increasing affordability, may soon become the standard for
visualizing occult fractures and ligament disruptions.
A bone scan taken two or three days after the injury can confirm
the diagnosis. Or your physician may request a second set of X-rays
after a week to ten days. Other diagnostic imaging tests that may be
used include magnetic resonance imaging (MRI) and computed
tomography (CT) scan.
 Radiograph
of fractured scaphoid
 MRI
of fractured schaphoid
Classification.
Treatment decisions and outcome predictions are based on the
location and stability of the scaphoid fracture. Acute, nondisplaced
fractures are generally seen as a single lucent line through the
scaphoid. A fracture is considered unstable if more than 1 mm of
displacement is seen between fragments or if the fragments are
angled. In addition, the fracture is considered unstable if the
lateral radiographic view shows malalignment of the carpal bones
suggestive of fracture dislocation, or if the anteroposterior view
shows carpal widening suggestive of ligament disruption.
Fractures are localized within the proximal, middle (waist), or
distal third of the bone. The incidence of avascular necrosis
increases as fractures are located more proximally in poorly
vascularized areas. Most scaphoid fractures occur at the waist,
followed by the proximal pole and then the distal pole (1).
Orientation of the fracture is a clue to its stability (figure 3).
The most stable fracture orientation is the horizontal oblique,
wherein the axis of the load is perpendicular to the fracture line.
Transverse fractures may be unstable. The most unstable fracture has
a vertical oblique orientation; fragments are vulnerable to
longitudinal shearing forces from the radius.
Treatment
Treatment is determined by the fracture site, the degree of
displacement, and any associated injuries. Most scaphoid fractures
are treated with immobilization in either a cast that covers the
lower arm, the wrist and the thumb or one that covers the full arm,
wrist and thumb. Healing time can range from six weeks for fractures
in the top portion to six months for fractures in the lower portion.
The cast must be checked regularly to make sure that it fits
properly and prevents movement. After the cast is removed, a
rehabilitation program helps restore range of motion and strength
. ![[FIGURE 2]](scaphoid%20plaster.gif)
Even with immediate cast immobilization, however, not all
scaphoid fractures will heal properly. Surgical bone graft placement
with internal fixation is usually recommended when the scaphoid
fails to heal (non-union). This is successful in approximately 75
percent of cases.
Surgery is also required if the fracture is displaced or if there
are other injuries. During the operation, the surgeon will align the
bone and stabilize it with screws or pins. Sometimes a bone graft is
used to promote healing.
Scaphoid fractures often take a long time to heal. Any delay in
getting a diagnosis increases the risk of poor healing and the
probability of more problems later. An untreated scaphoid fracture
can lead to severe arthritis and eventually require surgery to fuse
or replace the joint.
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![[FIGURE 3]](scaphoid_injuries.gif)
