Meniscal root

What it is

Each meniscus has a front (anterior) root and a back (posterior) root, fixing its horns into bone near the centre of the tibial plateau. When you stand, the meniscus is squeezed and tries to spread outwards. Secure roots resist this, turning the load into tension around the C-shape, known as hoop stress, and protecting the cartilage underneath.

Why it matters for patients

A root tear lets the meniscus slide out from the joint, called extrusion, so it no longer cushions the bone. Pressure on the cartilage rises sharply, and untreated root tears are linked to faster arthritis and sometimes weakening of the bone beneath.

The posterior root of the medial meniscus often tears in middle-aged adults with a small movement, such as squatting or kneeling, felt as a sudden pop and sharp pain at the back inner knee. The posterior root of the lateral meniscus tends to tear with ACL injuries in younger, active people. In suitable patients, repairing the root back to bone aims to restore meniscus function. In knees that already have advanced arthritis, repair is less likely to help.

How it is examined

Root tears can be subtle on MRI, so radiologists and surgeons look specifically for signs such as meniscus extrusion and a gap at the root. They are confirmed at arthroscopy.