Distal Radius Fracture
The wrist joint is formed where the two long bones of the forearm, the radius and ulna, meet the small carpal
bones. The radius is larger at the wrist than the ulna. The radius is located on the same side of the wrist as the
thumb. "Distal" is a word that describes a body part as being farther away from the center of the body. The distal
radius is the part of the radius that meets the wrist. "Proximal" means the opposite--closer to the center of the
body. The proximal radius is the part of the radius that meets the elbow.
The end of the radius is capped with a smooth, slippery layer of cartilage. The carpal bones are also capped with
cartilage. The cartilage that caps the ends of bones in joints is known as articular cartilage. Articular cartilage is
smooth and slippery. This lowers friction in the joint and allows the bones to glide smoothly against one another as
the wrist moves. Articular cartilage is slightly softer and more rubbery than bone.
The end of the radius where it meets the carpal bones and is capped with cartilage is known as the articular
surface. The articular surface has two shallow valleys that provide places for two of the carpals to sit. The scaphoid
bone sits in the scaphoid fossa and the lunate sits in the lunate fossa. The ulnar notch is formed on the side where
the head of the ulna sits. The distal radius forms a triangular tip called the radial styloid.
Bones are held together by fibrous bands known as ligaments. Several ligaments serve to hold the radius to the
carpal bones. Ligaments also hold the ulnar head to the distal radius to form the distal radioulnar joint (DRUJ).
Tendons are strong, fibrous structures that attach muscles to bones. Most of the muscles that move the wrist and
fingers are located in the forearm. Their tendons cross over the wrist joint. Two tendons, the brachioradialis and
pronator quadratus, attach to the distal radius.
The front of the wrist, the side on the same side as the palm of the hand, is called the palmar side or the volar side.
The back of the wrist, the side opposite the palm of the hand, is called the dorsal side. When the wrist is bent
backward, away from the palm of the hand, it is known as extension or dorsiflexion. When the wrist if bent forward,
toward the palm of the hand, it is known as flexion, volar flexion, or palmar flexion.
The outer layer of the bone is dense, rigid, and hard. It is known as the cortex. The inner bone is more spongy. It is
known as cancellous bone. Blood vessels are able to carry nutrients through the bone to keep it healthy.
Fractures of the Distal Radius
Fractures of the distal radius are very common because it is natural to extend the arm out to protect one's self during
a fall or collision.
Young, healthy adults have bones that are solid and strong. In this population, a simple fall usually does not result in
a broken wrist. However, a more traumatic injury can break a stronger bone. Young men are more commonly
involved in motor vehicle accidents and sporting injuries. And so distal radius fractures are not unusual among
younger adult males.
Older adults, especially females, have thinner, more brittle bones. Hormonal changes result in less uptake of
minerals needed for building strong bones. In this population, simply tripping and falling to the floor on an
outstretched hand can result in a fracture of the distal radius.
Children have more flexible bones that are still developing and maturing. They may also break their wrists with a fall
on an outstretched hand (FOOSH), but they tend to bend rather than completely snap the distal radius. This is
known as a buckle fracture or a torus fracture.
Diagnosing and Evaluating Distal Radius Fractures
History
Distal radius fractures occur after a traumatic injury. The older and more brittle the bone, the less traumatic the
injury has to be to break the wrist. An elderly woman may report a simple trip and fall, while a young male may
report a sporting injury or motor vehicle accident. The injury results in immediate pain and swelling. Most people
seek care at the emergency department the same day the injury occurs. Others will assume they have simply sprained
the wrist and delay seeking care until pain persists for a day or two.
ྕ
Fall on an outstretched arm (FOOSH)
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Traumatic sporting injury or motor vehicle accident
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Immediate pain and swelling
Physical Exam
Tenderness over the distal end of the radius is concerning for a distal radius fracture. A thorough physical
examination seeks not only to confirm that the distal radius has been broken, but also to rule out other injuries and
ensure that nerves and vessels are intact. Sensation and strength of the fingers is often tested to ensure that nerves
are intact. Capillary refill (pinching the fingers to see if they quickly turn pink again) is checked to make sure that
blood is making its way to the fingers. Swelling is often present. Sometimes a deformity is visible as well. When the
distal radius is bent backwards, a "dinner fork deformity" may be present. It is also important make sure that the
skin was not compromised over the fracture site. Sometimes a sharp bone fragment can poke through the skin,
putting it at risk of infection.
Inspection: swelling and deformity
Palpation: tenderness over the distal radius
Skin: open or closed fracture
Nerves: active movement of the fingers and sensation
Vessels: good pulse and capillary refill takes less than 2 seconds
X-rays
Distal radius fractures are usually easy to see on x-rays. Rarely, a nondisplaced fracture is not seen on the initial x-
rays taken right after the injury. This is known as an occult fracture. If an occult fracture is suspected, the wrist
may be splinted and new x-rays obtained 10 to 14 days later. The healing process can be seen on the new x-rays.
X-rays are not just used to confirm that the radius has been broken. They are also essential for evaluating the nature
of the fracture. At least three different views should be obtained to ensure that the fracture is aligned well. One view
may demonstrate good alignment in one plane while another view demonstrates displacement in another plane.
CT scan (computer-aided tomography)
X-rays are usually sufficient for diagnosing and evaluating wrist fractures. However, if the bone is broken in small
pieces or if the fracture involves the joint surface, it may be important to get a more detailed, 3-dimensional view. If
this is the case, a CT scan can be obtained.
Treating Distal Radius Fractures
Without treatment, fractures may heal incorrectly. This is known as malunion. Or they may not heal at all. This is
known as nonunion. The purpose of treatment is to hold bone fragments in place so the bone can heal correctly.
As a bone heals, it forms a callus that begins to fuse the pieces back together. If the bone is bent, the callus will fuse
the pieces together crooked. If the pieces are too far apart, the callus may not be capable of bridging the gap to fuse
the pieces together. If there is too much movement at the fracture site, the callus may continually break down before
it is able to fuse the pieces together.
Non-operative vs. Operative Treatment
The object of treatment is to hold the bone fragments together and in good alignment long enough that a callus can
form and the fragments can fuse back together and heal.
Often a cast or splint is sufficient to hold the fracture in place. Rigid material is used to immobilize the wrist so that
there is very little movement at the fracture site.
Sometimes it is impossible to hold the fragments in good alignment with a cast. If this is the case surgery may be
necessary. Hardware such as pins or screws can be used to hold the fragments in alignment long enough for the
fracture to heal.
When the skin over the fracture is compromised so that bacteria can get to the broken bone, it is known as an open
fracture or a compound fracture. Because of the risk of infection, open fractures are treated surgically. The wound
is irrigated, cleansed, and repaired. If the fracture is displaced, hardware may be used at that time to fix the broken
fragments in place.
Reduction
If a fracture is nondisplaced, meaning that there is a crack through the distal radius but the fragments have not been
pulled apart, then the fracture can generally be treated with casting.
If the fracture is displaced, meaning that the fragments have been pulled apart or out of alignment, a reduction
must be performed. To reduce a broken bone means to pull the fragments back into alignment.
A closed reduction is when then bone is pulled back into alignment without making an incision over the skin. This
is usually done by applying traction across the fracture site (pulling on the arm on both sides of the fracture) and
nudging the displaced fragment back into place.
A closed reduction is, of course, painful. And so some form of anesthesia is usually provided. A hematoma block is
when a numbing medication such as lidocaine is injected into the fracture site. This numbs the broken bone so the
reduction is not as painful. Conscious sedation is when medicine is given to the person to make them very sleepy and
less aware of the pain of the reduction.
After the fracture has been reduced, a splint or cast is applied to immobilize the wrist and hold the fragments in
place. The elbow is sometimes immobilized as well to prevent the radius and ulna from rotating and to keep the
brachioradialis tendon from pulling at the fracture site and displacing the fracture within the cast.
X-rays are obtained to confirm that the reduction was successful and the fracture is well-aligned.
It is not always possible to reduce a broken distal radius into perfect, anatomic alignment. Orthopedic surgeons have
studied fractures for years and have some idea of how much displacement or angulation results in a bad outcome.
There is some consensus about the following limits:
Dorsal angulation (how far backwards the fragment is tilted)
o
Normal is about 10-12° of volar (forward) tilt
o
Acceptable is 0° (neutral tilt)
Radial inclination (the angle of the articular surface and radial styloid compared with the axis of the bone)
o
Normal is about 23°
o
Acceptable is up to 5° of loss of the angle
Radial length (how much collapse and shortening of the bone)
o
Acceptable shortening of the bone is less than 3 mm
Intra-articular step-off (if the crack goes up into the joint surface, how much step-off is there at the crack)
o
Acceptable step-off is less than 2 mm
If an adequate closed reduction is not possible, an open reduction may be necessary. This involves making an
incision over the fracture site and using surgical instruments to move the fragments back into alignment. An open
reduction may be necessary if the fragments are caught on one another or if there is soft tissue stuck between them.
If an open reduction is performed, hardware is usually placed to hold the fragments in place. This is known as open
reduction with internal fixation (ORIF).
Surgical Fixation
If an adequate closed reduction cannot be obtained and the person is active and healthy, surgical fixation may be
recommended. Surgery is done in a sterile environment in the operating room under anesthesia. Different methods
of doing this all have advantages and disadvantages.
Percutaneous pinning
o
A closed reduction is performed and wires are pushed through the skin and drilled into the bone and
across the fracture site to keep the fragments from displacing
o
A splint or cast is applied after surgery to protect the fixation
o
Not as invasive as other surgical methods
o
Not as stable fixation as other surgical methods
o
Pins are usually removed in the office after about 3 weeks
o
Casting is usually continued for a couple of weeks after pin removal
External Fixator
o
A closed reduction is performed and pins are inserted above and below the fracture site. The pins
protrude out the skin and attach to a device known as an external fixator. The external fixator is adjusted
to provide constant traction across the fracture site that keeps the fracture from shortening and
displacing.
o
Not as invasive as ORIF but more invasive than percutaneous pinning
o
May not be as capable of maintaining stable fixation of some fractures as ORIF
o
The pins and external fixator are usually removed in the office after about 5 to 6 weeks
o
The wrist may be protected with a cast or brace for a couple of weeks after removal of the device
Open Reduction-Internal Fixation (ORIF)
o
An incision is made over the wrist. Soft tissue is dissected away from the fracture site. Instruments are
used to move the fragments into alignment. A metal plate and screws are used to hold the fragments
together. The incision is closed with sutures.
o
A splint or cast is applied after surgery to protect the fixation
o
More invasive than other methods but allows more anatomic reduction and stable fixation
o
May be dorsal (back of the wrist) or volar (front of the wrist)
o
Hardware is usually left in place forever
Not everyone with unstable or displaced distal radius fractures is a good candidate for surgery. The heart, kidneys,
and other organs must be healthy enough for anesthesia. People with poorly controlled diabetes are poor surgical
candidates because of the risk of infection and poor wound healing. Sometimes the benefits of a better reduction and
more stable fixation do not outweigh the risks of surgery. When this is the case, the fracture is reduced as well as
possible and treated without surgery.
Recovery Following a Distal Radius Fracture
It is important to keep the cast or splint clean, dry, and intact. A wet or poorly molded cast can cause skin breakdown
and sores. If the cast is too tight, too loose, gets wet, is rubbing the skin, or if there are other complications, the clinic
where the cast was applied should be notified sooner than later.
Swelling within a cast can result in discomfort and can pinch nerves and blood vessels which can cause further
problems. It is important to ice and elevate the wrist as much as possible.
Too much activity with the broken wrist, even in a cast, may cause the fracture to displace or may delay healing. The
broken wrist should be put at rest. In certain cases, the orthopedic surgeon may consider allowing athletes to play in
a cast or workers to work in a cast depending on the stability of the fracture.
Young, healthy bone typically takes about 4 to 6 weeks to heal solid enough that casts and splints can be
discontinued. Young children heal more quickly. Older people take longer to heal. Smoking, osteopenia (thinner
bones), a sedentary lifestyle, and failing to follow the doctor's instructions can all make it take longer for the fracture
to heal. Some people may require 8 weeks or more of casting and bracing.
X-rays are obtained periodically to evaluate healing. Callus formation is visible on x-rays and is an indicator of how
well the bone is healing.
Once the cast has been discontinued, the wrist may be very stiff. Physical therapy may be recommended to help
regain strength and range of motion.