Every knee has a medial and lateral meniscus which are C-shaped pieces of fibrocartilage that absorb stress and act as cushions between the bones at the knee. At birth, the meniscus is not C-shaped, but discoid (round like a discus). 

With growth and walking, the discoid meniscus evolves into its normal C-shape. In some children, the lateral meniscus continues to stay discoid with growth. The incidence is approximately 3-5% of the population.

What are the Symptoms of a Discoid Meniscus?

The most common presentation is a 6 to 8 year old child with a "snapping" or a "clicking" in their knee as they walk. However, it is also possible for the onset to occur in early adolescent years when a child's sporting activities increase.  

Luckily, discoid meniscus is usually pain-free, and the clicking noise is what is noticed. In some instances, as the child grows older, the click increases and may cause recurrent locking, where they are unable to straighten or bend their knee fully. This will commonly also manifest as pain in the knee.

What Tests Confirm a Discoid Meniscus ?

X-ray 

The X-ray appearance is usually normal in discoid meniscus.

MRI

To confirm the diagnosis, an MRI is usually necessary to actually visualize the discoid meniscus.

What is the Treatment for Discoid Meniscus?

In most cases, if there is no significant locking or pain, treatment is non-surgical, consisting of stretching and strengthening exercises for the Quadriceps and Hamstring muscles plus proprioceptive and knee control exercises.

In cases where there is significant disability, surgical excision may be needed. In most cases, a partial excision to preserve the cushioning function may be sufficient. You will need to consult with an Orthopaedic Surgeon for a surgical opinion.

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