Even without a deep understanding of knee anatomy, you’ve probably heard of the knee’s meniscus—perhaps because a pro athlete or someone you know has torn their meniscus.

Each knee joint has two layers of cartilage (meniscus): the lateral meniscus on the outside of the knee, and the medial meniscus on the inside. Read: Understanding Meniscus Tears

But you may not know that the causes of a torn meniscus can evolve quite a bit as you age.


What is the meniscus?

The meniscus is a flat layer of cartilage that cushions the knee joint where the leg bones meet. There are two menisci in each knee—one on the inside of the knee (the medial meniscus) and one on the outer knee (the lateral meniscus). Together, they cushion the joint, acting as shock absorbers, and also allow the knee to move smoothly.

When we’re young, the meniscus is tough and rubbery and can withstand the forces it’s subjected to fairly well. But with age, the meniscus becomes more fragile and more easily torn or damaged. This is why different activities present different risk to trigger a meniscus tear, depending on your age.

See Causes of Meniscal Tears

Most likely causes of knee pain caused by a meniscus tear

Younger than 30
Those who are younger than 30 are most likely to tear their meniscus through an acute injury while playing a sport or participating in physical activity.

This can include:

  • A blow to the knee from the front or side, such as when a football player is tackled or a basketball player hits the floor
  • An over-rotation of the knee from twisting or pivoting, for example when a soccer or basketball player is changing direction or stopping quickly
  • Planting a foot awkwardly or on an uneven surface, such as when an athlete is running “suicide” drills or accidentally falls
  • A hyperextension of the knee, which can occur when a basketball or volleyball player jumps and comes down on another player’s foot

Older than 30
As we age and the meniscus becomes less resilient, the causes of a meniscus tear are increasingly connected to wear and tear:

  • Degeneration of the cartilage in the knee, known as osteoarthritis, can wear away cartilage both from the ends of the bones (articular cartilage) and from the meniscus itself, making it more vulnerable to tearing.

    See Knee Cartilage Repair, Regeneration, and Replacement

  • Repetitive movements such as squatting or kneeling can raise risk for a meniscus tear, which could affect those with jobs that require these movements frequently, such as plumbers or carpet layers.
  • Acute injury, such as those listed above, can be even more hazardous for those who stay active or play a sport in middle age.
  • Sometimes, tears can develop with no known cause and gradually start causing symptoms.

Symptoms of a meniscus tear include immediate pain and a popping sensation in the knee when injury occurs, pain on the inside or outside of the knee, swelling in the knee, or knee locking.

See Symptoms of Meniscal Tears

If you are experiencing knee pain symptoms and you suspect you may have a torn meniscus, make an appointment to see you doctor.

Read more: Meniscal Tear Treatment

Learn more:

Diagnosing Meniscal Tears

Knee Surgery for a Torn Meniscus

Dr. Terry Gemas is an orthopedic surgeon and the founder of Lakewood Orthopaedics and Sports Medicine in Dallas, TX. He specializes in sports medicine and has been in practice for more than 15 years. Dr. Gemas has treated professional athletes and currently serves as the head team physician for several Dallas-Forth Worth area high school, college, and club teams.