Glossary
Lateral meniscus
Quick answer
The lateral meniscus is the cartilage cushion on the outer side of the knee. It is rounder and more mobile than the medial meniscus and carries a large share of the load on the outer half of the joint, as knee surgeon Dr. Pablo Gelber explains to patients in Doha.
What it is
The lateral meniscus is almost circular and covers more of the lateral tibial plateau than its inner partner. It is attached less firmly to the capsule and not at all to the LCL, so it moves more as the knee bends and rotates. The popliteus tendon passes through a gap in its outer rim at the back.
Why it matters for patients
The lateral meniscus is often torn together with an ACL tear during a pivoting injury. Because the outer side of the knee is shaped convex on convex, it relies heavily on this meniscus, and losing a large part of it can speed up cartilage wear on the outer knee. For this reason surgeons make a particular effort to repair rather than remove lateral meniscus tears where possible.
Some children are born with a discoid lateral meniscus, a thicker, disc-shaped meniscus that is more prone to tearing and may cause clicking, catching or a knee that will not fully straighten. Tears of the back attachment, the lateral meniscal root, are also linked with ACL injuries.
How it is examined
Examination looks for outer joint-line tenderness and pain on twisting tests. MRI shows the tear pattern and whether the meniscus is discoid.
Frequently asked questions
Is a lateral meniscus tear worse than a medial one?
Not necessarily, but the outer knee depends more on its meniscus, so preserving it matters a great deal. Treatment depends on the type and location of the tear.
My child's knee clicks on the outer side. Could it be a discoid meniscus?
It is one possible cause, especially if the clicking comes with pain, swelling or difficulty straightening the knee. A knee specialist can examine the child and decide whether an MRI is needed.
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