Knee MRI Scan Explained

A knee MRI is done to look inside the knee and see if there is an explanation for pain or other symptoms.  A knee MRI gives a detailed look at the anatomy inside the knee.  We can see all types of tears, broken bones, and collections of fluid.

What is a knee MRI?

A knee MRI is a test that looks at the detailed anatomy of the knee for abnormalities.  A knee MRI is done without radiation.  Instead it uses radio waves and magnets to form an image inside the body.

How long does a knee MRI take?

A knee MRI typically takes 30-60 minutes.  This depends on the type of MRI ordered by your doctor.

Reasons to get a knee MRI

Reasons for a knee MRI include symptoms like pain, weakness, locking, swelling, trouble bearing weight, after trauma or injury, in addition to others.

Sometimes MRI is ordered because a finding on an X-ray needs clarification.  MRI is ordered if there is suspicion for a fracture of the bone which has not shown up on X-ray.

What can knee MRI diagnose?

MRI is good at diagnosing sprains and tears of the tendons and  ligaments.

We can see tears of the menisci of the knee.

MRI can show us sprains and tears of muscle around the knee.

We can see arthritis including the detailed location and extent of cartilage damage.

We can diagnose all types of abnormalities of the bone that X-rays sometimes do not show.  These can include bone bruises, fractures, bone lesions and tumors.

MRI of the knee can show us collections of fluid around the knee. This can be joint fluid, fluid in a bursa, cysts, or swelling from various causes.

Will an MRI show knee inflammation?

Yes, knee inflammation can be seen on an MRI.  This can be seen as edema or fluid accumulation around the knee. There are various causes of inflammation like arthritis, injuries, and infections.

Will an MRI show arthritis in the knee?

Yes, knee MRI will show arthritis of the knee.  We can see cartilage damage directly.  We can also see abnormalities of the bone next to the joint.  We can see how extensive the arthritis is, often better then an X-ray.

Normal knee MRI vs abnormal

A normal knee MRI shows us normal tendons, ligaments, menisci, cartilage, bones and muscles.  An abnormal MRI will show us an abnormality of one or more of these structures.

An abnormal MRI will provide a detailed look at the abnormal structure and what the diagnosis is.  This will help the referring doctor treat your symptoms.

Risks of a knee MRI

There are few risks of a knee MRI.  Some implanted devices can cause trouble for someone having a knee MRI like some pacemakers.   The MRI technologist will screen you for any safety concerns and implanted devices.  An MRI done with contrast can pose a risk of an allergic reaction.  

How to prepare for a knee MRI

Often the facility performing the MRI will provide detailed instructions.  Be sure to tell the technologist about any allergies, implanted devices, pregnancy status, breast feeding, and kidney problems.

The MRI is an enclosed tube.  Some patients with claustrophobia can be given a sedative or referred to an open MRI machine.

How a knee MRI is performed

In preparation for the scan, you will change into a hospital gown and remove all jewelry.  An IV line may be placed if the test was ordered with contrast.

You will lay on a padded table and be inserted into the MRI machine which is like a large round tube.  You will hear noises as the machine works.  The technologist will be in a separate control room giving you instructions over a microphone.

After the test, you can go back to your usual activities.   There are usually no problems or reactions after the test.

Is it worth it to get a knee MRI?

Yes,  because the knee MRI will often diagnose the cause of your knee symptoms.  This will help determine the best treatment.

When will I get the results?

Usually same or next day in many practices.  Exams ordered as stat may be read within an hour.

Knee MRI: summary

A knee MRI is a detailed look inside your knee without the need for an invasive procedure.  We can often diagnose the cause of your knee symptoms.  This will direct the most appropriate treatment.

Disclaimer: The content of this website is provided for general informational purposes only and is not intended as, nor should it be considered a substitute for, professional medical advice. Do not use the information on this website for diagnosing or treating any medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.

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