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Knee MRI Scan

Australians are known for their love of the great outdoors and their active lifestyles. So, it shouldn’t come as too much of a surprise that our country has topped the world for the highest rate of anterior cruciate ligament (ACL) injuries.

The ACL is a ligament in the knee, and a tear of damage to it can be debilitating. If knee pain is felt, a doctor will often arrange for an MRI scan to determine whether the ACL has been damaged. While a tear to the ACL is a serious and common condition of the knee, there are many other ailments or damage to parts that can occur within the knee that an MRI scan can help to detect.

An MRI of the knee can detect a number of conditions including damaged cartilage, ligaments, tendons and meniscal injury, arthritis, tumors, bone fractures, and more.

An MRI scan of the knee will help a doctor discover what the issue is and, consequently, assist them to make a diagnosis and to determine the best treatment plan.

How do knee MRI scans work?

An MRI is magnetic resonance imaging that shows images of a knee’s structure. They allow doctors to see knee joints, including bones, cartilage, tendons, ligaments, muscles, blood vessels and internal body structures. MRIs are more detailed than an X-ray, which shows just bones.

A knee MRI is an effective non-invasive treatment that uses magnets and radio waves to capture a high quality image of the area. The images produced also show a large number of different angles of the area, increasing the likelihood of capturing the affected issue.

Unlike X-rays, an MRI doesn’t use radiation. Instead, it harnesses radiowaves from data that already exist in the body, meaning it won’t cause chemical change or damage to tissue.

A knee MRI is performed inside a circular metal-shaped machine. Once the patient is inside, the radiologist will capture a number of images on a computer screen, each showing a thin slice of the body.

From here, the doctor or radiologist can study the images to determine the issue.

Why might you need a knee MRI?

If a doctor suspects an issue with a ligament or tendon in the knee, they will almost always suggest an MRI to confirm their suspicions. However, knee MRIs can detect far more than just ligament and tendon injuries or tears.

MRIs are generally ordered by a doctor when there is pain or lack of mobility with the knee. Especially if an x-ray isn’t able to detect the problem. If you are experiencing any of the following issues, you may require a knee MRI.

  • Knee injuries from an accident or fall
  • Persistent knee pain that doesn’t improve over time
  • A swollen or inflamed looking knee area
  • Lack of mobility in the knee area
  • Knee pain or discomfort when the knee is moved a particular way
  • A popping sensation or feeling in the knee
  • As a check-up after knee surgery
  • Acute knee pain that’s developed suddenly

Below are a number of conditions that an MRI can help diagnose.

  • Bone infections
  • Tumors of the bone and surrounding soft tissues
  • Arthritis
  • Fluid build up in the knee
  • Bone fractures or breaks
  • Torn ligaments
  • Sprains
  • Infections
  • Damaged or torn meniscus
  • Problems with the knee joint
  • ACL tears
  • Extra fluid in the knee
  • Collateral ligament injury
  • Inflammation in the knee
  • Degenerative joint disease

How to prepare for your knee MRI scan

An MRI will need to be ordered from a referring physician. So, prior to your MRI appointment, you should have already spoken about your knee issue with your GP.

Eating or drinking before a knee MRI is usually okay unless your physician advises otherwise.

Once you arrive at your GP you won’t need to do anything too drastic to prepare. You’ll be required to move anything metal (like a necklace, bracelet, earrings, hair pins, piercings and hearing aids).

It’s important that you don’t wear hairspray or makeup to the appointment, as these contain metal particles, which can mess with the MRI images. If you have a metal object inside your body, like metal pins for a broken bone or implanted medical device, you should let the radiologist know.

What To Expect from your knee MRI scan

During the scan

When you arrive at your knee MRI appointment, you will be given a hospital gown to change into. Some variations of MRI’s may require the patient to have dye to be administrated intravenously so that the issue can be identified in the scan. This will depend on your specific issue.

From here, a technician will position you on a table, so that your knee is positioned correctly for the scan. This will usually involve strapping it in. An electric machine will slide your body inside the MRI machine so that the bottom half of your body is inserted.

A knee MRI will generally take between 30 and 60 minutes, but in some cases, it can take up to two hours. Your technician will fit you with earplugs and a buzzer. When you press the buzzer you’ll be able to speak to the technician who is located in a separate room.

It’s very important for a patient to stay perfectly still during an MRI so that the detailed images don’t get blurred. Don’t be surprised or off-put by the loud sound during the scan, the machine is very noisy.

A patient shouldn’t feel anything during a scan. Sometimes people feel warm during a scan, but if this happens then the technician should be notified.

Once the knee MRI scan is completed, the patient will be slid out of the machine and be allowed to change back into their original clothes.

After the scan

Patients should generally feel normal after an MRI scan. The exception to this is patients who have been sedated due to claustrophobia reasons. In this case, these patients will require a recovery period and will need someone to drive them home.

Occasionally a patient made feel mild side effects, like slight nausea, or local pain. If a patient has a rash or other allergic symptoms appear after an MRI test, there’s a chance that they could be having an allergic reaction and a doctor should be notified immediately.

The waiting time for results will depend on the severity of your condition, as well as the clinic that you went to. Results usually take around 1-2 weeks, but can be returned quicker if the condition is suspected to require urgent medical attention.

What are the benefits of knee magnetic resonance imaging (MRI)?

MRIs are generally an expensive test when they are conducted without medicare cover, but are a very effective tool for identifying issues within or around the knee. If an MRI is conducted for a patient in a public hospital, the cost of the test will be completed covered by Medicare. Below are some reasons why Knee MRIs are commonly used.

  • They provide a very detailed image, allowing a technician to see tendons, ligaments and bone abnormalities that aren’t displayed in a regular x-ray.
  • MRIs are non-invasive and don’t involve any radiation, meaning they are a very safe procedure.
  • An MRI can show a hairline fracture that may not be evident on a normal x-ray.
  • The detailed image from an MRI can help a doctor determine whether knee surgery is required.


Why would a doctor order a knee MRI?

A doctor will initially discuss your symptoms, pain or discomfort with you and do a physical exam of the affected area. If they suspect an issue that can be confirmed through the use of an MRI, they will refer you for the scan.

MRI tests are also often ordered after knee surgery so that healing and potential issues can be monitored. In another case an MRI is commonly ordered is when pain is felt within the knee region, but an xray , computed tomography (CT) scan or other tests shows inconclusive results.

How long does a knee MRI take?

The length of time a Magnetic Resonance Imaging (MRI) of the knee takes is dependent on the patient’s issue. A normal MRI will usually take around 30 – 60 minutes. In some cases where in-depth analysis is required, the scan can take up to two hours.

A contrast MRI is when a patient is given a contrast agent like contrast dye intravenously in order to provide greater image quality to identify unusual blood vessel activity. This type of MRI can take slightly longer, however, it won’t usually take any longer than two hours.

Is a knee MRI uncomfortable?

A patient should not be able to feel anything from the actual radio waves and magnetic process of the scan. However, they may feel minor discomfort from the positioning of their original condition was painful. For example, a patient with a torn ACL or fractured femur may be required to position their leg in a particular way for the MRI images to be captured successfully. If this is the case, the technician will be extremely gentle in positioning your leg so that the least amount of pain possible is caused.

Will a doctor automatically recommend an MRI if I have acute knee pain?

No, a doctor will discuss your symptoms and conduct a physical exam first. They will only refer you for an MRI scan if they believe the scan can identify your condition.