The meniscus is the most important cushion you have in your knee.  A meniscus is a c-shaped disc soft cartilage that sits between the femur and the tibia.  If the meniscus is injured and the cushioning is lost, arthritis and pain can occur.

There are many structures within the knee which can cause pain.  By far, one of the most common causes of knee pain is a meniscus tear.  I see many patients with a meniscus tear and wish to have a second opinion. When I ask them what is a meniscus… they are typically not very accurate with their description.  In order for you to make an informed decision about your tear, it is important that you have a good understanding of what a meniscus is and what your treatment options are.  Let’s begin.

What is a Meniscus?

What is a Meniscus?
Normal appearance of a meniscus

A meniscus is a crescent or “c”-shaped cartilage disk that’s found in the knee.  There are actually two menisci in each knee.  We have one on the inner side of the knee which we call the medial meniscus and one on the outer side of the knee which we call the lateral meniscus.  The menisci serve a very important function in the knee.  Our meniscus  functions as a shock absorber or cushion to minimize the stress on  another type of cartilage that we have in the knee which we call the articular cartilage.  The articular cartilage coats the ends of our bones within a joint.  By protecting the articular cartilage, the meniscus helps prevent the onset of arthritis.    The meniscus also serves to improve stability of the knee.  The meniscus acts like a block stuck behind a tire to prevent a car from rolling.  The less meniscus you have, the more stress the rest of your knee sees and the more unstable the knee may be.

See below for a long list of related articles for further reading about meniscus tears.

Understanding “what is a meniscus”, enables you to understand how a tear can affect your knee

If a friend tells you they have a “torn cartilage” they are generally referring to a torn meniscus.  When the meniscus is not functioning properly, or it is torn, then you may feel pain with turning, pivoting or twisting.  In addition, you may develop a feeling of instability, or a feeling that the knee wants to give way.  Unfortunately the meniscus does not possess regenerative capabilities.  That means that the tissue  can wear out over time.  Because the body does not possess the ability to heal a meniscus (like a cut on your skin) these tears rarely heal on their own.   When a tissue has poor regenerative potential, the likelihood of suffering a degenerative or attritional meniscus tear is very high.  Simply stated that means that our meniscus can simply wear out and tear from the cumulative stress that we have put on our knee throughout our lives.

What is a meniscus

The meniscus functions as a shock absorber.  In the picture to the right you can see how weight bearing or walking forces the meniscus to move towards the outside of the knee when pressure is applied.  This is how the meniscus takes the stress off of the articular cartilage on the end of the bones.

 

 

from aaos.org

The image at left reveals a normal meniscus sitting between the femur above and the tibia below. The meniscus is a C-shaped structure in your knee that is made of fibro-cartilage. It acts as a cushion for the knee when it’s bearing weight.

Most meniscal tears in adults are degenerative …

that is, the meniscus simply wore out from years of use. Most adult patients with a torn meniscus don’t even recall how or when the meniscus tear happened.

The presentation for a meniscus tear is usually quite different in children or adolescents. Meniscus tears in children are usually traumatic in nature and will usually arise from a non-contact twisting injury.

 

So the next time you’re asked, what is a meniscus, you will hopefully know! :-)

 Keep on learning!  Recommended follow up reading:

Types of meniscus tears

Why do mensicus tears hurt?

Running and meniscus tears

Is surgery necessary for all meniscus tears?

Meniscus transplant surgery 

Recovery from meniscal surgery?

PRP injections for meniscus tears

Disclaimer:  this information is for your education and should not be considered medical advice regarding diagnosis or treatment recommendations. Some links on this page may be affiliate links. Read the full disclaimer.

About the author:

Howard J. Luks, MD

Howard J. Luks, MD

A Board Certified Orthopedic Surgeon in Hawthorne, NY. Dr. Howard Luks specializes in the treatment of the shoulder, knee, elbow, and ankle. He has a very "social" patient centric approach and believes that the more you understand about your issue, the more informed your decisions will be. Ultimately your treatments and his recommendations will be based on proper communications, proper understanding, and shared decision-making principles – all geared to improve your quality of life.