What is the meniscus, and what types of meniscus tear are there?

What the meniscus does

Each knee has two menisci: the medial meniscus on the inner side and the lateral meniscus on the outer side. They spread body weight across the joint, protect the joint cartilage, add stability and help lubricate the knee. Without them, load is concentrated on a smaller area of cartilage, which is why surgeons try to preserve as much meniscus as possible.

Zones and blood supply

Only the outer rim of the meniscus has a good blood supply. Surgeons often call this the red zone, while the inner part is the white zone. Tears in the outer zone have a better chance of healing after repair, whereas tears in the inner zone usually do not heal and, if they cause symptoms, may need trimming.

The tear patterns on an MRI report

• Vertical or longitudinal: runs along the length of the meniscus, often in younger people after a twist and frequently repairable
• Bucket-handle: a large vertical tear whose inner part flips into the joint and can lock the knee
• Radial: cuts across the meniscus from the inner edge outwards and can disrupt its ability to hold load
• Horizontal: splits the meniscus into upper and lower layers, common with age
• Flap: a loose tongue of tissue that can catch
• Complex or degenerative: several patterns together in a worn meniscus
• Root tear: a tear at the anchor point of the meniscus to the bone

Why the type matters

The pattern, location, your age and how the knee behaves together decide whether rehabilitation, repair or trimming makes sense. Dr. Gelber goes through the MRI images with patients at Aman Hospital in Doha and explains what the report means for their own knee.