Knee MRI: What It Shows and How the Procedure Is Performed

The knee works like a hinge: bones, cartilage, ligaments, and menisci bear the load and guide movement. If a doctor has given you a referral for a knee joint MRI, it is useful to understand in advance what the examination will show. Below is what this examination shows, how it is performed, and how it differs from computed tomography.

What a knee joint MRI is and what it shows

MRI is a method of obtaining layered images of tissues using a magnetic field, radio waves, and a computer. X-rays are not used: the machine records the response of hydrogen nuclei, which are abundant in the body as part of water.

For the knee this is valuable: soft tissues are seen clearly. MRI is used to examine muscles, ligaments, tendons, and joints, such as the knee.

How a knee MRI is performed

The machine is a large device with a short tunnel and a sliding table. The person lies down and remains still: the clarity of the images depends on this, and during part of the scan you may be asked to hold your breath. The scanner knocks and clicks loudly, so earplugs or headphones are provided. The radiologic technologist operates the machine from the adjacent room and can hear the patient. The procedure takes from 15 minutes to an hour, sometimes longer. Sometimes a contrast agent is injected into a vein so that details appear better.

Before the scan, everything containing metal is removed:

• jewelry, watches, hairpins, hearing aids;
• a bra with metal and clothing with zippers — these are changed for a hospital gown;
• coins and keys from pockets;
• makeup.

The questionnaire asks about pregnancy and breastfeeding, surgeries, kidney problems, metal parts in the body (clips, pacemaker, dental prostheses), allergy to contrast, tattoos: dark dyes may contain metal. If you are afraid of confined spaces, tell staff in advance — medication to help you relax may be possible, and open-configuration machines are available.

After a scan with contrast, you are asked to wait at the clinic for about 30 minutes. Mild side effects — nausea, rash, headache, metallic taste, dizziness — usually pass quickly. If a relaxant was given, someone else should take you home: you must not drive for 24 hours. The images are reviewed by a radiologist, and the referring doctor receives the report, usually in 1–2 weeks.

How a knee MRI differs from computed tomography

Computed tomography of the knee joint works on X-rays, whereas MRI uses neither X-rays nor ionizing radiation — which is why it is chosen when repeat examinations are needed. Compared with CT, the procedure is noisier and often takes longer, and it usually requires being inside a narrow tunnel. People with certain medical implants or other non-removable metal inside the body may not be able to undergo MRI safely.

What is visible on an MRI of a healthy knee

The images show bones, cartilage, ligaments, tendons, and menisci. MRI clearly shows soft tissues and in many cases helps distinguish healthy tissue from altered tissue. What counts as abnormal is decided by the doctor based on the images together with the examination and symptoms.

Meniscus on MRI: what can be seen

The menisci are cartilage pads between the bones that bear load and distribute it across the joint. This is soft tissue, and MRI shows soft tissues well. Conclusions are drawn by the doctor based on the images and examination: the MRI report alone, without examination and history of injury, does not become a diagnosis.

Contraindications and when the examination is prescribed

The limitations are related to the powerful magnet: a pacemaker, artificial joint and other implants, metal fragments — this is a safety issue decided by the clinic staff before the procedure. Pregnancy, breastfeeding, kidney disease, and allergy to contrast are reported in advance. MRI is referred when it is necessary to understand the cause of symptoms, assess the soft tissues of the knee, plan treatment, or check how it is working.

See a doctor immediately: a knee MRI is a planned examination and is not in itself a reason to call an ambulance. 103 or 112 — if after contrast administration you develop difficulty breathing or swallowing, cough and wheezing, rash and hives, or fainting.

This material is for reference: it explains what a knee MRI shows but does not replace a doctor's consultation — discuss the report on your images with the person who referred you.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer