Discoid Lateral Meniscus (Knee)
What Is a Discoid Lateral Meniscus?
The meniscus is a C-shaped cartilage cushion in the knee that helps absorb shock and protect the joint cartilage as the thigh bone moves over the shin bone. Each knee has two menisci: one on the inner (medial) side and one on the outer (lateral) side.
The lateral meniscus can have a congenital variant called a discoid meniscus, which is thicker and more disc-shaped—similar to a hockey puck—rather than the normal C-shape. Many children and teens have a discoid meniscus and never know it. However, this shape can make the meniscus more prone to tearing, especially with twisting injuries.
The most common mechanism for a discoid lateral meniscus tear is when the knee is bent and then twisted, such as during sports or active play.
Symptoms of a Torn Discoid Lateral Meniscus
Symptoms of a discoid lateral meniscus tear or lateral meniscus tear may include:
- Pain along the outer (lateral) side of the knee
- Swelling that develops within a few hours after injury
- Locking, catching, or difficulty fully straightening the knee
- Popping or clicking inside the knee
Diagnosis
A careful physical exam of the knee by a pediatric orthopedic specialist often suggests a meniscus tear. An X-ray is usually obtained first to rule out bone injury. An MRI is then used to confirm the diagnosis, evaluate the shape of the meniscus, and look for associated injuries.
Treatment
Treatment of a symptomatic discoid lateral meniscus is typically surgical, with the goal of preserving as much healthy meniscus as possible to protect the knee long term.
During arthroscopic surgery (minimally invasive “camera” surgery):
- The central portion of the discoid meniscus is trimmed and shaped (saucerized) to create a more normal C-shaped meniscus.
- Any torn areas are assessed. If the tear can be repaired, meniscus repair (stitching the tissue) is performed.
- If the tear is not repairable, only the damaged portion is removed (partial meniscectomy) back to stable, healthy tissue to help prevent further tearing and protect the joint cartilage.
When a repair is performed, physical therapy and a period of activity restriction are important to protect healing. Children and teens typically require about three months before returning to sports, depending on the extent of the repair and guidance from their care team.
Expert Pediatric Knee Care at Rady Children’s
The Orthopedics & Sports Medicine team at Rady Children’s Hospital–San Diego specializes in diagnosing and treating discoid meniscus and lateral meniscus tears in children and adolescents. Our pediatric orthopedic surgeons use meniscus-preserving techniques whenever possible to support long-term knee health and safe return to activity.