The wrist isn’t a single bone in the human body. Eight small bones called carpal bones make up the wrist, arranged in two rows of four. These bones are collectively called the carpus; in addition to connecting the arm to the hand while allowing the hand to bend and rotate freely, the carpus forms a canal that protects the delicate nerves, ligaments, and tendons that run through the wrist into the hand.
In addition to the eight carpal bones, the radius and ulna—the long, thin bones of the forearm that run from the elbow to the carpal bones—can be fractured. When these bones break near the area of the carpal bones, this can also be considered a wrist fracture.
This means that the injury commonly referred to as a “wrist fracture” isn’t just the fracture of one specific bone. There are many different ways that these interconnected bones can be damaged or dislocated.
What are some different types of wrist fractures?
A fracture is said to be open when the jagged end of the broken bone breaks through the skin, and closed when it does not, although the skin near the area of a closed fracture may swell or “tent” over the site of the break. A comminuted fracture involves more than two pieces of broken bone. A nondisplaced fracture occurs when the bone is cracked but the ends are not separated, while in a displaced fracture the broken ends of the bone are pulled away from each other.
A fracture of the distal radius happens at the end of the radius bone, not within the carpal bones. While the radius can break in many different places, the break will be considered a wrist fracture if it is found about one inch from the end of the bone. There are many different ways that this bone can break. In a Colles fracture, the broken end of the radius is tilted upwards. An intra-articular fracture extends into the wrist joint, while an extra-articular fracture does not.
The ulna is the smaller of the two long, slender bones in the forearm. The styloid process of the ulna, which projects from the bone close to the wrist, is frequently fractured.
A scaphoid or navicular fracture involves a break in the scaphoid bone, which is one of the carpal bones. This bone has a long, curved shape when compared to the other carpal bones. The other carpal bones are the lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate.
Even if these bones are not cracked, trauma to the area can cause dislocation, meaning that the bones are knocked out of the position they should be in. Because so many delicate nerves, blood vessels, and tendons involved in the function of the hand and wrist run through this area, a patient may experience significant pain or difficulty with normal life activities even if no bone in the area is broken.
What can cause wrist fractures?
Most wrist fractures happen when someone falls and catches themselves with their outstretched hand, transmitting the entire force of their falling bone through the bones of the wrist. This can cause serious fractures in bicycle and motorcycle accidents, when a rider is ejected from their bike by the force of the crash and flies through the air before falling in their wrist. In car accidents, wrist fractures often happen when the occupants of a vehicle realize that a crash is about to happen and brace themselves by pushing against the steering wheel or dashboard with an outstretched hand. Wrist fractures can also happen when the wrist is twisted, when a heavy object falls or slams into the wrist, or when the wrist is caught between heavy objects like a door and doorframe.
How are wrist fractures treated?
Because so many different bones make up the wrist, treatment of fractures in this area will be dependent on the exact injury. In some cases, surgery may be necessary to reposition bones that are dislocated or displaced. A reduction surgery means that the displaced ends of the bone will be drawn back together. Internal fixation may involves holding the broken fragments of bone together with wire or screws. In some cases, a surgeon may use a bone graft taken from a different area of the patient’s body to help the broken ends of the bone knit more quickly.
In other cases, it may be possible to stabilize the wrist and allow the fracture to heal without surgical intervention. A cast or splint will usually be used; the exact design and placement of the case depends on the nature of the fracture.
Some types of wrist injuries may heal faster with the help of a bone stimulator, a device that uses low-intensity ultrasonic or pulsed electromagnetic waves.
