X-rays of the Extremities

By Sara Foster

(X-ray of the Arm, Leg, Hand, Wrist, Foot, Ankle, Shoulder, Knee, or Hip)

Procedure overview

What are X-rays of the extremities? 

X-rays use invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs on film. Standard X-rays are performed for many reasons, including diagnosing tumors or bone injuries.

X-rays are made by using external radiation to produce images of the body, its organs, and other internal structures for diagnostic purposes. X-rays pass through body structures onto specially-treated plates (similar to camera film) and a "negative" type picture is made (the more solid a structure is, the whiter it appears on the film). Instead of film, X-rays may also be made by using computers and digital media.

When the body undergoes X-rays, different parts of the body allow varying amounts of the X-ray beams to pass through. Images are produced in degrees of light and dark, depending on the amount of X-rays that penetrate the tissues. The soft tissues in the body (such as blood, skin, fat, and muscle) allow most of the X-ray to pass through and appear dark gray on the film. A bone or a tumor, which is denser than the soft tissues, allows few of the X-rays to pass through and appears white on the X-ray. At a break in a bone, the X-ray beam passes through the broken area and appears as a dark line in the white bone.

X-rays of the extremities are often used as the first step in diagnosing injuries of the extremities, but may also be used to evaluate other problems involving the bones and/or soft tissues.

Other related procedures that may be used to diagnose problems involving the extremities include computed tomography (CT scan), magnetic resonance imaging (MRI), arthrography, or bone scan. Please see these procedures for additional information.

Anatomy of the arm and hand

The arm consists of the following bones:

  • Humerus. The largest bone of the upper arm. The lower end connects with the two bones of the lower arm (radius and ulna).

  • Radius. One of the bones of the forearm. The upper end is small and forms a part of the elbow joint. The lower end is large and forms a part of the wrist joint.

  • Ulna. One of the bones of the forearm, on the little-finger side of the forearm, that forms with the humerus the elbow joint and serves as a pivot in rotation of the hand.

The hand is composed of many different bones, muscles, and ligaments that allow for a large amount of movement and dexterity. There are three major types of bones in the hand itself, including the following:

  • Phalanges. The 14 bones that are found in the fingers of each hand and also in the toes of each foot. Each finger has three phalanges (the distal, middle, and proximal); the thumb only has two.

  • Metacarpal bones. The five bones that compose the middle part of the hand.

  • Carpal bones. The eight bones that create the wrist. The carpal bones are connected to two bones of the arm, the ulna bone and the radius bone.

Reasons for the procedure

X-rays of the extremities (such as the arm, leg, hand, foot, ankle, shoulder, knee, hip or hand) may be performed to assess the bones of the extremity for injuries, such as fractures or broken bones, or evidence of other injuries or conditions, such as infection, arthritis, tendinitis, bone spurs, tumors, or congenital abnormalities. X-rays of the extremities may also be used to evaluate bone growth and development in children.

X-rays of joints may be done to evaluate damage to soft tissues, such as cartilage, muscle, tendons, or ligaments, and to assess for the presence of fluid in the joint, and other abnormalities of the joint such as bone spurs, narrowing of the joint, and changes in the structure of the joint.

There may be other reasons for your doctor to recommend an X-ray of the extremities.

Risks of the procedure

You may want to ask your doctor about the amount of radiation used during the procedure and the risks related to your particular situation. It is a good idea to keep a record of your past history of radiation exposure, such as previous scans and other types of X-rays, so that you can inform your doctor. Risks associated with radiation exposure may be related to the cumulative number of X-ray examinations and/or treatments over a long period of time.



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