Knee MRI

Knee MRI: Information and Get a Scan

Knee injuries can be as frustrating as they are debilitating. The knee is one of the most complex joints in the body. It has many important structures that need to work in unison for the joint to function correctly. Damage to one of these individual structures can result in pain. If left untreated can lead to more serious knee complications in the future.

Research has shown 23% of participants have experienced a form of knee injury, 51% of those injuries required hospitalization. The most prevalent are ligament injuries, accounting for 40%, while 25% are miscellaneous injuries, such as contusions and strains.

Furthermore, 24% are patella related injuries, and 11% are meniscus injuries. With many possible injuries, each involving different aspects of the knee joint, it’s virtually impossible to determine the cause of knee pain through physical examination alone. An MRI scan can provide a detailed image of the knee, showing any damage, and allows physicians to make an accurate diagnosis.

Early intervention is essential to a quick and full knee recovery. An MRI scan of the knee is a painless diagnostic procedure that can help produce an accurate diagnosis, to get you back on your feet. Continue as we discuss what the most common knee injuries are, and what you can expect from a knee MRI scan.

What is the Anatomy of the Knee Joint?

The knee is a type of synovial hinge joint, consisting of:

Bones

• Patella (Kneecap)
• Femur
• Tibia

Ligaments

• Anterior Cruciate Ligament (ACL)
• Lateral Cruciate Ligament (LCL)
• Medial Cruciate Ligament (MCL)
• Posterior Cruciate Ligament (PCL)

Tissues

• Meniscus
• Joint Capsule
• Synovial Membrane
• Hyaline Cartilage

The soft, fibrous tissues ensure the bones are protected from friction and shock damage, while also keeping the joint lubricated. The ligaments hold the knee joint together, keeping the hinge joint moving in the correct direction. This integrated network of structures work to move your knee, support the weight of your upper body and are necessary for you to perform everyday functions like walking, sitting and standing. The knee can only function correctly when all of these structures work in unison, when one is damaged it puts further strain on the rest of the joint components.

What is a Knee MRI Scan?

Doctors often use a knee MRI (Magnetic Resonance Imaging) scan to examine the structures inside your knee joint more closely, especially when symptoms such as pain, stiffness, or swelling persist without a clear diagnosis.

A knee MRI is a non-invasive imaging test that uses a powerful magnetic field and radio waves to create detailed images of the inside of your knee. It doesn’t involve any radiation, so it’s a safer option than some other types of imaging, such as X-rays or CT scans.

While a knee MRI focuses on generating high quality images of the lower limb, MRI technology is used for all sorts of body parts, from the brain to the spinal cord. Due to its accuracy and detail, an MRI can identify problems that other imaging methods may overlook, making it a crucial tool for diagnosing complex or chronic knee issues. If you’re experiencing knee pain, an MRI could be the right option for you.

What a Knee MRI Scan Can Diagnose

Doctors will often use an MRI scan to assess bone fractures that might not show up on a standard X-ray, especially when swelling or soft tissue damage suggests deeper injury.

MRI is particularly effective at showing articular cartilage, which cushions the joint and can become worn or damaged in conditions such as osteoarthritis.

While knee MRI scans are focused on the joint itself, radiologists are also trained to spot signs of more serious conditions, such as bone tumours, especially if you have unexplained knee pain or swelling.

 Here are some of the most common diagnoses of knee conditions:

• Meniscus tear: Radiologists can easily spot both partial and full meniscal tears, the cartilage that cushions your knee joint.

• ACL tear: An MRI will show whether the anterior cruciate ligament (ACL) is sprained, partially torn, or completely ruptured—information that’s vital for planning treatment for torn ligaments.

• MCL sprain or tear: The scan can reveal damage to the medial collateral ligament (MCL), helping your doctor decide whether you need rest, physiotherapy or knee surgery.

• Cartilage damage (chondromalacia): An MRI can pick up early signs of cartilage deterioration, often before you notice any symptoms.

• Osteoarthritis: MRI images reveal subtle joint changes, including thinning cartilage and swelling, which help track the progression of the condition.

• Patellar tendonitis: Doctors use MRI to detect inflammation or small tears in the tendon that connects your kneecap to your shinbone.

• Bone bruise: Unlike X-rays, MRI can reveal bone bruises—deep injuries that affect the marrow beneath the surface.

• Baker’s cyst: The scan helps identify fluid-filled cysts behind the knee, often linked with arthritis or meniscus injuries.

• PCL tear: An MRI will also reveal damage to the posterior cruciate ligament (PCL), which can impact the knee's stability.

• Osteochondritis dissecans: Radiologists can see areas where bone and cartilage may have died due to reduced blood flow.

• Joint effusion and synovitis: MRI scans clearly reveal swelling and inflammation within the joint, providing clues to the underlying cause.
  

Why Should I Get an MRI Knee Scan Procedure?

Knee pain means there has been damage to a component of the knee joint. Sometimes it can be a simple strain and can be managed with rest and physiotherapy. However, other times it can be a serious injury to an important structure or the sign of a degenerative disorder.

The most common injuries include:

• Ligament Tears
• Meniscus Tears
• Patellar Dislocation
• Contusion
• Fracture

A Magnetic Resonance Imaging (MRI) scan uses a powerful magnetic field to capture multiple images of the knee joint. These detailed pictures showcase the soft tissues, ligaments, and muscles surrounding the joint. Since the knee is a complex network of structures, the best way for a physician to provide a diagnosis, is through examining an MRI knee scan. An early diagnosis leads to early intervention and is imperative to making a full recovery.

If you are experiencing any of the following symptoms,

• Knee joint pain that increases with exercise
• Limited range of motion
• Sudden weakness in your knee
• Direct injury to the knee joint
• Swelling or fluid collection around the knee

It could be of value to have an MRI knee scan to help identify the root of the problem.

What Does an MRI of the Knee Show?

An MRI knee scan produces detailed images of the knee joint, including,

• Tibial and Femoral Condyles (rounded end of the bone)
• Patella
• Ligaments
• Meniscus
• Joint Capsule

Unlike an X-ray, an MRI scan procedure can show the extent of damage to the fibrous tissue structures in the knee. This allows doctors the opportunity to diagnose,

• Fractures
• Degenerative diseases (such as osteoarthritis)
• A build-up of fluid in the Knee
• Infections
• Tumours
• Decreased range of motion
• Joint weakness
• Damage to ligaments, meniscus, or soft tissues
• Possible ligament or tissue tears

Early intervention is important for the recovery of knee injuries, an MRI scan increases the ability to accurately diagnose the cause of your knee pain, and begin the rehabilitation process.

How Do You Read a Knee MRI Scan?

An MRI scan takes images at three different angles:

• Axial - From the top looking down
• Sagittal - From the side
• Coronal - From the front

A great way to understand how an MRI scan works is to imagine the knee as a tomato. Slices of the tomato are being cut from one side to the other, each one of those slices represents a single MRI image. Each image is a cross-section of the knee joint, as it moves from one side to the other, along one of the three angles.

A radiologist is a doctor who specializes in reading and interpreting MRI scans. They will move through the images, across one angle at a time to identify the key knee structures, looking for changes and inconsistencies in colour or shape. They will be able to identify issues such as fluid build-up, deterioration of important knee structures, or ligament tears. If an issue is identified, they can move through the set of images across the other two angles to assess the severity of the damage.

The radiologist will sign off on your scan and send it to your physician, who will discuss the results with you and advise a treatment plan if required. In some instances, there will need to be a follow-up MRI scan to evaluate the effects of the treatment, or if there is no decrease in pain.

How an MRI Scan of the Knee Works

An MRI scanner uses magnets and radio waves to stimulate protons in your body’s water molecules. When these protons return to their normal state, they emit signals. The machine picks up those signals and turns them into images.

Doctors can use advanced MRI techniques, such as T1 and T2 mapping, to compare healthy tissue with damaged areas. These techniques help them detect subtle abnormalities, particularly in cartilage and soft tissue.

What Equipment is Used?

Radiology teams usually perform knee MRIs using high-field MRI machines, such as those with a 3 Tesla (3T) magnet. These scanners produce higher-resolution images than low-field machines, which means clearer pictures and more accurate diagnoses.

To improve image quality, radiographers will place a dedicated knee coil around your leg. This special device captures more detailed signals from the joint.

What Are the Risks of MRI?

Doctors generally consider MRI scans to be a very safe procedure. Because MRI exams don’t use ionising radiation, you can have multiple scans over time without increasing your health risks.

However, you should always tell the MRI team about any metal implants or medical devices, such as pacemakers or cochlear implants. Some devices aren’t MRI-compatible.

In some cases, your radiologist may recommend using a contrast agent to enhance the images. If so, they’ll inject a substance called gadolinium into a vein in your arm or hand. While most people tolerate it well, a small number may experience allergic reactions.

If you feel anxious or claustrophobic in enclosed spaces, speak with your doctor beforehand. You might be given medication to help you relax.

What do I Need to Do to Prepare for an MRI Knee Scan?

Before your scan, it is common for your technician to go over your medical history, including any allergies. Since some procedures use an iodine contrast material, your technician needs to know if you have any known allergies to this material. At this time, it is important to inform the technician of any implanted medical device, such as a pacemaker or defibrillator. MRI technology advancements have made it safe for those with implanted medical devices to undergo an MRI scan. However, the powerful magnetic field can potentially cause changes in the settings of these devices. It’s advised to also inform your radiographer if you are pregnant. There is currently no link between MRI scans and adverse birth defects, but it is important to disclose your full medical history.

Furthermore, before your scan, you will need to change into a hospital gown. Some clinics will allow you to wear your clothing, so long as they are loose-fitting and do not contain any metal fasteners. Each clinic has its guidelines about eating and drinking before a procedure. Generally, it is not necessary to fast before an MRI knee scan unless otherwise specified.

The Procedure Explained: What to Expect

The entire scan usually takes between 30 and 45 minutes. You’ll lie on your back on the MRI table, and the team will position your knee inside the scanner.

Once the scan begins, you’ll hear loud tapping or knocking sounds. These noises are completely normal and just part of the machine doing its job. To help reduce any discomfort, the team will offer you earplugs or headphones. Some clinics also let you listen to music during the scan.

It’s important to stay as still as possible to ensure clear images, as even small movements can blur the images.

What Happens After a Knee MRI Scan?

When the scan finishes, you’ll be able to get up and carry on with your day as normal. If you had contrast dye, the team may recommend drinking more water to help flush it out.

A radiologist will then review your images and write a detailed report. Your doctor will go over the results with you and explain the next steps, whether that means physiotherapy, further tests, or a referral to a specialist.

How Long Should an MRI Knee Scan Take?

An MRI scan of your knee should take on average 10–30 minutes. You will be instructed to wear a hospital gown or loose-fitting clothing without metal clasps or zippers. Certain types of metal can interfere with the MRI machine, causing blurred images. If this occurs the scan will need to be repeated.

It is important to stay extremely still during this procedure. Sudden movements during the scan can also produce blurred images. If this happens, the scan will need to be repeated causing a longer MRI procedure.

How Much Does a Knee MRI cost?

Prices for knee MRI scans can vary based on your location, the hospital you choose, and whether or not you need a separate appointment with a consultant to get a referral.

We're the UK's largest imaging network with over 200 scanning centres to choose from, with complete pricing transparency that includes a pre-scan consultation, your referral, your scan, copies of your report and images, and a post-scan follow-up call. Scan.com makes it easier to compare prices across all of the options near you with no hidden costs, with knee MRI scan costs starting from just £295.

The benefit of choosing a private MRI knee scan is reduced wait times. Currently, to receive a non-urgent MRI through the NHS, the wait time can be up to 18 weeks or more. Our private MRI clinics offer a quick alternative, most appointments can be made within two weeks. Knee injuries can often begin as a small issue, growing more severe and painful over time. It’s important to identify the issue quickly to intervene with the appropriate medical treatment.

Getting the Results

Many imaging centres aim to deliver results within a few days. However, timelines can vary depending on the complexity of your scan or the urgency of your referring doctor's need for the results.

If your results are urgent, your GP or specialist can often request a faster turnaround.

Get a Knee MRI Scan

If you have knee pain, swelling, or mobility issues that aren’t improving, you can book a private knee MRI scan today. If you’re unsure whether an MRI is suitable for you, one of our expert clinicians is available for a personalised consultation. They can discuss your symptoms and concerns and help you decide what to do next. 

The Bottom Line

Knee injuries can be debilitating, but early intervention can increase the potential to make a full recovery. Taking advantage of an MRI knee scan can help speed up your diagnosis and get you on the road to rehabilitation.

If you are thinking about an MRI knee scan and would still like additional information, visit our Frequently Ask Questions page. Or contact us, our team will be happy to assist you with any questions you may have.

FAQs

Does your whole body go in for a knee MRI?

Usually not. The scanner will only need to cover the lower half of your body, although this may vary depending on the machine used.

What should I wear for a knee MRI?

Loose, metal-free clothing works well, but most patients will be asked to change into a gown for safety.

Can you have an MRI with a knee replacement?

Yes, most modern metal knee replacements are made with non-magnetic materials, which can safely undergo MRI scanning. Although, the metal in the implant may affect image quality. Your radiology team will check the implant material and adjust the settings to get the best results.

How long does it take to get results?

Most people receive their results within a few working days, although this can vary.

How long should I wait after a knee injury before having an MRI?

That depends on your symptoms. If pain and swelling continue beyond a few days, or if your doctor suspects serious damage, your doctor may refer you for an MRI sooner.

References

1. https://bjsm.bmj.com/content/34/3/227.2
2. https://www.innerbody.com/image/skel16.html
3. https://pubmed.ncbi.nlm.nih.gov/22506941/
4. https://josr-online.biomedcentral.com/articles/10.1186/s13018-020-01638-1
5. https://www.radiologyinfo.org/en/info/kneemr
6. https://regenexx.com/blog/read-knee-mri/#gref
7. https://medlineplus.gov/ency/article/007361.htm