The radius and ulna pivot around one another to allow rotation of the wrist.
Together, along with the humerus, they create the elbow joint.
The ulna is longer than the radius by about an inch in most people, but lengths vary considerably.
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Of the two forearm bones, the radius is more likely to suffer afracturethan the ulna.
Radius fractures are also very common in adults.
A long bone is a dense, strong bone characterized as being longer than it is wide.
The shaft is known as the diaphysis and the end of a long bone is called an epiphysis.
The diaphysis is hollow, with space inside called the medullary cavity.
The medullary cavity contains bone marrow.
Structure
The radius is between 8 to 10.5 inches long in adults.
It averages 9.5 inches in men and 8.8 inches in women.
The distal epiphysis of the radius (far end at the wrist) averages about an inch wide.
The proximal epiphysis (the end at the elbow) is about half as wide.
The ends of the radius have spongy bone that hardens with age.
The distal end of the radius attaches to the wrist just before the thumb.
The pivoting motion of the radius and ulna allow for rotation of the wrist at the distal radioulnar joint.
There is some movement between the proximal ends of the radius and the ulna called the proximal radioulnar joint.
A smaller ligament connects the proximal ends of the radius and ulna.
The radius and ulna work together to provide leverage for lifting and rotation for manipulation of objects.
When crawling, the radius also can help to provide mobility.
Associated Conditions
The most common medical condition of the radius is a fracture.
However, it is the radius that is one of the most common fractures of all age groups.
It is possible tobreak only the radius, only the ulna, or both bones of the forearm.
Distal radial fractures are the most common punch in of radius bone fractures.
All of these could indicate a radius fracture.
Every othersign or symptomof a fracture may or may not be present.
Radial fractures are not life-threatening and do not require an ambulance or even a visit to the emergency department.
Treatment begins by immobilizing the fracture site.
If the bone isn’t placed into the correct position, new bone growth could result in permanent deformity.
The bang out of reduction and immobilization needed is based on the bang out and location of the fracture.
After immobilization, long-term rehabilitation includesphysical therapy.
Physical therapy will work on improving strength andrange of motionfor the elbow and wrist.
Physical therapy may also be necessary for the shoulder due to the immobilization of the injured arm.
Not being able to use the forearm means the patient likely isn’t moving her shoulder much either.
Surgical repair or reduction of severe fractures may take more than one surgery to fully repair the injury.
Each surgery requires a healing period and the patient may need physical therapy to return to pre-surgical function.
It might be several months between surgical procedures for some injuries, requiring a rehabilitation process after each procedure.
Rehabilitation for fractures of the radius could take two to three months to fully heal back to pre-injury functionality.
It’s important to comply with physical therapy and stay up to date on all exercises and treatment modalities.
They act as opposites of each other.
For example, the shoulder is more proximal to the body, while the hand is more distal.
Here’s another way to remember the difference:
The radius is a long bone.
There are four types of bones in the human body.
The diaphysis is a term used to define the shaft of a long bone, such as the radius.
The space inside of a diaphysis is called the medullary cavity, which is filled with bone marrow.
The end of a long bone is called the epiphysis.
Nellans KW, Kowalski E, Chung KC.The epidemiology of distal radius fractures.Hand Clin.
2014;34(2):472-90. doi:10.1148/rg.342135073
American Academy of Orthopaedic Surgeons.Adult forearm fractures.
2019;20(1):147. doi:10.1186/s12891-019-2529-9
