- radiographic exam of the joint
A joint x-ray is a radiographic image of a place where bones in the body connect. X-rays consist of electromagnetic waves of energy. They penetrate the body to varying extents depending on the density of the structures being viewed. The result is back and white images of interior portions of the body.
Who is a candidate for the test?
A person who has pain, swelling, redness, limited motion or deformity of any joint is a candidate for a joint x-ray. X-rays can also be used to check on a person's progress after an operation.
How is the test performed?
The person having the x-ray will remove clothing to expose the affected joint. The x-rays may be taken sitting, standing or lying on an x-ray table.
Sometimes, iodinated contrast material, or dye, will be injected into the joint. An x-ray taken after the dye is injected is called an arthrogram.
The joint is placed over the x-ray film. The x-ray tube is positioned over the joint and the film is exposed. The exposure lasts only a fraction of a second. Usually several x-rays will be taken.
The technologist will examine the pictures. If they are adequate, the individual is free to leave.
In recent years, CT, a special three-dimensional x-ray, and the MRI, a special three-dimensional image using magnets, are being used to obtain more information about joint abnormalities than can be obtained by conventional x-rays.
What is involved in preparation for the test?
Before the exam, an individual needs to remove all jewelry or other metal objects that may interfere with the process. He or she will also remove splints or prosthetic devices. Women will be asked if they might be pregnant.
What do the test results mean?
Joint x-rays can show:
- fluid in the joint
- narrowing of the joint space
- abnormal bony growths
- different types of arthritis
- bad alignment, or joints in which the parts do not match up as intended
- increase or decrease in bone density
- abnormal calcifications, because of calcium deposits
- loose pieces in the joint