An extremity X-ray is a picture of your hand, wrist, arm, foot, ankle, knee, hip, or leg. It is done to see whether a bone has been fractured or a joint dislocated. It is also used to check for an injury or damage from conditions such as an infection, arthritis, bone growths (tumors), or other bone diseases, such as osteoporosis.

X-rays are a form of radiation, like light or radio waves, that are focused into a beam, much like a flashlight beam. X-rays can pass through most objects, including the human body. X-rays make a picture by striking a detector that either exposes a film or sends the picture to a computer. Dense tissues in the body, such as bones, block (absorb) many of the X-rays and look white on an X-ray picture. Less dense tissues, such as muscles and organs, block fewer of the X-rays (more of the X-rays pass through) and look like shades of gray on an X-ray. X-rays that pass only through air look black on the picture.

Why It Is Done

Extremity X-rays are done to:

• Find the cause of pain in an extremity.
• See if your bone is fractured or your joint is dislocated.
• See if fluid has built up in the joint or around a bone.
• See if your bones are positioned properly after treatment for a fracture or dislocation, such as after placing a cast or splint on an arm or leg. An X-ray also may be done after a doctor places a device such as a pin or an artificial joint in a bone.
• Find changes in your bones caused by conditions such as an infection, arthritis, bone growths (tumors), or other bone diseases. See pictures of osteoarthritis of the hip and osteoarthritis of the knee.
• Find foreign objects such as pieces of glass or metal.
• Check to see if a child's bones are growing normally.
• See if your bones and joints are in the correct position after joint replacement surgery.

How To Prepare

Before the X-ray test, tell your doctor if you are or might be pregnant. Pregnancy and the risk of radiation exposure to your unborn baby (fetus) must be considered. The risk of damage from the X-rays is usually very low compared with the potential benefits of the test. If an extremity X-ray is absolutely necessary, a lead apron will be placed over your abdomen to help shield your baby from exposure to the X-rays.

You do not need to do anything before you have this test.

How It Is Done

An extremity X-ray is taken by a radiology technologist. The X-ray pictures are usually read by a doctor who specializes in interpreting X-rays (radiologist). Some other types of doctors can also review extremity X-ray pictures for common problems, such as fractures or arthritis.