Glossary
MRI of the knee
Quick answer
A knee MRI uses a strong magnet and radio waves, not radiation, to create detailed pictures of ligaments, the meniscus, cartilage, tendons and bone. It is the main scan for suspected ACL, meniscus and cartilage injuries, although it is always read alongside the examination, explains Doha knee surgeon Dr. Pablo Gelber at Aman Hospital.
What the scan feels like
You lie on your back on a sliding table, with the knee resting in a coil that looks like a padded cradle. For a knee scan, usually only your legs and lower body go into the machine, so many people who dislike enclosed spaces cope well.
The scanner makes loud knocking and buzzing sounds, and you are given earplugs or headphones. The key is to keep the knee completely still for about 20 to 30 minutes. You must remove metal objects, and tell the team about pacemakers, implants, metal fragments or pregnancy beforehand. Contrast injection is rarely needed for a routine knee MRI.
What it tells the surgeon
MRI shows soft tissues that X-rays cannot: a torn ACL, the shape and location of a meniscus tear, cartilage defects, bone bruising, tendon damage and fluid collections such as a Baker's cyst. It helps decide whether a meniscus tear might be repairable and whether other injuries need treating at the same time.
MRI is very sensitive, and it often shows changes that are normal for age, such as meniscus wear in people over 40 without symptoms. That is why the surgeon matches the images to your symptoms and examination rather than treating the scan alone.
Frequently asked questions
Do I need an MRI for every knee problem?
No. Many knee problems are diagnosed by examination and X-rays. MRI is most useful when the result will change treatment, such as a suspected ligament or meniscus tear.
Can I have an MRI with metal in my knee?
Most modern knee implants, screws and anchors are MRI-safe, though they can blur the images nearby. Always tell the team about any metal so they can check.
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