MRI · Knee
What a knee MRI shows, and what the report means
Read Your Scan Editorial Team·Last updated
Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →
The short answer
A knee MRI shows the two menisci, the cruciate and collateral ligaments, the cartilage surfaces, the tendons around the joint, the bone marrow inside the bones, and any excess joint fluid. X-rays show bone; an MRI is ordered when the question is soft tissue.
A knee MRI makes detailed pictures of the soft tissues and bones inside your knee — the cartilage, ligaments, tendons, and menisci. This page explains what it looks at and what common report terms mean.
What this scan shows
A knee MRI is very good at showing soft tissues that X-rays cannot, including the menisci (the knee’s cushions), the major ligaments, the tendons, the joint cartilage, and the bones. Doctors order it after an injury, for pain, swelling, locking, or instability, or to plan treatment. Some findings, like mild wear, are common with age and may not be the source of symptoms — your doctor connects the images to your exam.
Common findings, in plain words
Meniscus tear
A tear in one of the C-shaped cushions in the knee. Tears range widely, and some — especially age-related ones — cause few or no symptoms. Your doctor considers whether it explains what you feel.
ACL or other ligament sprain/tear
A stretch or tear of one of the knee’s stabilizing ligaments. The report describes the extent so your doctor can discuss stability and options.
Cartilage thinning (chondromalacia)
Softening or thinning of the smooth cartilage on the joint surfaces. It is common with age and activity and is graded by degree.
Joint effusion
Extra fluid within the knee joint, often a sign of irritation or a recent injury. It frequently settles as things calm down.
Bone marrow edema (bone bruise)
A bright area within the bone that often reflects a bruise or stress response. Many resolve over time. Your doctor interprets it with your history.
Baker’s cyst
A fluid-filled sac behind the knee. It is common, often harmless, and usually related to fluid in the joint.
Terms you might see
- Meniscus
- One of two crescent-shaped cushions of cartilage that pad and stabilize the knee joint.
- Ligament
- A band of tissue that connects bone to bone and helps keep the knee stable — for example the ACL.
- Cartilage
- The smooth, slippery surface covering the ends of bones so they glide easily in the joint.
- Effusion
- Extra fluid inside a joint, often described when there is swelling or irritation.
- Edema
- Fluid or swelling within tissue that shows up as a brighter area on certain MRI images.
Questions to ask your doctor
- 1.Do the MRI findings explain the pain, swelling, or instability I feel?
- 2.Is any finding likely age-related rather than from a recent injury?
- 3.What are my treatment options, including non-surgical ones?
- 4.Would physical therapy help before considering other steps?
- 5.Do I need any follow-up, and when should I check back?
See these findings on your own scan
Upload your scan (de-identified in your browser) and your radiologist’s report, and every finding is mapped onto the images, explained in plain language and scored — free, no card needed. Informational only — not a diagnosis.
FAQ
- Does a meniscus tear on my MRI mean I need surgery?
- Not necessarily. Many meniscus tears, especially age-related ones, are managed without surgery. Your doctor weighs your symptoms, activity, and exam — not the images alone — when discussing options.
- What is a bone bruise on a knee MRI?
- Bone marrow edema, sometimes called a bone bruise, is a bright area in the bone that often follows an impact or stress. Many heal over time. Your doctor interprets it alongside your history.
- Is a Baker’s cyst behind my knee dangerous?
- Baker’s cysts are common and usually harmless, often related to extra fluid in the joint. Your doctor can explain whether it needs any attention in your case.
Related
Go deeper
Sources
- Patient-facing procedure descriptions (MRI, CT, X-ray, ultrasound)RadiologyInfo.org — Radiological Society of North America & American College of Radiology
- MRI scan — overview, how it is performed and resultsNHS (United Kingdom)
- ACR Appropriateness Criteria and practice parameters for reportingAmerican College of Radiology
Read Your Scan is informational only — not a medical diagnosis, and not a substitute for a licensed radiologist or your doctor. If you have urgent symptoms, seek care.