Discoid Meniscus in Children and Adolescents

The meniscus is a C-shaped wedge of cartilage that acts as a shock absorber between the tibia (shinbone) and femur (thighbone). Each knee has two menisci: the lateral meniscus on the outside of the knee and the medial meniscus on the inside of the knee.

With discoid meniscus, one or more of a child’s menisci is abnormally shaped. Instead of looking like a C, the meniscus may look like a D. It may also be thicker than normal. The unusual shape and thickness of the meniscus can make the knee more prone to injury. Discoid meniscus most often affects the lateral meniscus on the outside of the knee.

Many children and adolescents with discoid meniscus never experience symptoms and may not know they have the condition. For others, discoid meniscus can lead to injury, such as a torn meniscus, pain, and impaired mobility.

If the meniscus is severely damaged, the thighbone and shinbone may rub together and develop bone spurs that eventually lead to arthritis, putting a child at risk of needing knee replacement surgery by the time they’re a young adult.

Discoid meniscus is a congenital condition, meaning it’s present at birth. It’s unclear why some children are born with discoid meniscus.

Many children with discoid meniscus don’t have symptoms. If your child does have symptoms, they may include:

• A popping sensation in the knee
• Knee pain
• Knee swelling and stiffness
• Knee instability
• Limited range of motion
• Inability to fully straighten or bend the knee

The first step in diagnosing discoid meniscus is a medical history. Your child’s doctor will ask you and your child about their symptoms and when they began.

During a physical exam, your child’s doctor may move your child’s knee in several directions to test the range of motion and see if those movements cause pain.

Tests may include:

• Magnetic resonance imaging (MRI), a test that produces images of the soft tissues and bones around your child’s knee.
• Arthroscopy, a minimally invasive procedure in which an orthopedic surgeon inserts a small camera into the knee and looks at the size, shape, and health of the menisci.

If your child doesn’t have symptoms or limitations related to discoid meniscus, they may not need treatment.

Discoid meniscus that is painful or limits your child’s range of motion typically requires surgery, a procedure called saucerization. The goals of saucerization surgery are to:

• Reshape an abnormally shaped meniscus
• Repair a torn meniscus
• Prevent further tearing
• Restore knee function

In the Orthopedics and Sports Medicine Department at Boston Children’s Hospital, we’ll care for your child's knee with the least invasive option possible. Our team has treated thousands of children, adolescents, adults, and professional athletes with injuries ranging from the minor to the highly complex. We can provide your child with expert diagnosis, treatment, and care — as well as the benefits of some of the most advanced clinical and scientific research in the world.