Medically reviewed by Kyle Watford, M.D. McLeod Orthopaedics

“I think we need to do some tests.” When you visit an orthopedic specialist, diagnostic testing is likely the third phase used to identify the cause of your hip or knee pain. It follows a conversation with the specialist about when your joint started hurting and what kind of pain and how much pain you feel. Next comes the physical examination. The specialist looks at your knee or hip, maybe with a bit of poking and prodding.

Then, It’s Time to Look Inside

There are 3 basic types of diagnostic images that your Orthopedic Surgeon may use for this purpose: X-Rays, CT Scans and MRIs.  Here’s a quick look each one.

X-Rays

Using low-level radiation to take an image inside the body has been around for more than 100 years. By 1970, most Americans were having at least one X-ray every year. Much like today’s “photography”, most x-ray images are now captured as digital images and displayed on a video screen rather than on a sheet of film.

The process of “taking an X-ray” last only about 10 minutes. It offers a black and white image, where bones appear white and less dense; soft tissue appears gray.

Although the amount of radiation you receive is small, you may be given a lead apron to cover sensitive areas of your body.

CT Scan

Computed Tomography (CT) is a more sophisticated form of X-ray.  In this case, the patient lies on a table, while the X-Ray machine is guided by a computer to take a series of still images.  Each image is a virtual “slice” of the body.

These can be viewed as a series of stills – taken from different angles of positions.  Or, they can be played back, creating a moving picture – in much the way a film or video is a series of still images replayed in order to create motion.

The ability to capture many images often reveals problems that a single X-ray cannot. In general CT scans show bone anatomy better than any other test including MRI.

MRI

Rather than using radiation, Magnetic Resonance Imaging uses – as the name suggests – a magnetic field that is sent through the body.  The subtle vibrations caused by the magnetic field are recorded as images.  Color images are recorded in “slices” to offer a moving image.

The nature of the MRI enables it to more clearly show soft tissues, such as muscles and tendons. Some conditions, such as advanced arthritis of the knee or hip, may be better shown on the regular X-ray or CT scans.

MRIs are painless, but they are VERY LOUD. As the magnet turns on-and-off the patient will hear something like “Ka-Chunk-uh-Chunk” over and over. Some places will offer patients earplugs or even headphones with music.

Patients who suffer claustrophobia (fear of small, closed places) may need to find an “open MRI”, where they are not entirely inside the magnet.

Patients should not wear any metal in the MRI. The large magnet will attract it.  Any metal devices or pacemakers inside the body may also be affected. The medical staff is trained to ask about metal and implanted devices.

FINAL THOUGHT

None of these tests are painful. They should be covered by your insurance. And each test will help your Orthopedic Specialist determine your exact problem and plan the best treatment.

Find an Orthopedic Specialist near you.
Sources include:  McLeod Health, National Institutes of Health, American Academy of Orthopaedic Surgeons, Radiological Society of America