What is a discoid meniscus, and was my child born with it?

How it differs from a normal meniscus

Each knee has two menisci that cushion the joint. Normally the outer one is a crescent with an open centre. In a discoid meniscus the centre is partly or completely filled in, so it covers more of the shin bone. The tissue tends to be thicker and less organised, which makes it more prone to tearing and, in some children, less firmly anchored.

The main types

• Complete: the meniscus covers the whole outer part of the shin bone, like a full disc
• Incomplete: it is larger than normal but still has a partial open centre
• Unstable or Wrisberg type: the back attachment is missing or weak, so the meniscus moves excessively and often causes the clunking or snapping knee

Surgeons also look at whether any part of the rim is unstable, as this influences treatment.

Who has it

Discoid meniscus is uncommon overall but is reported more often in some populations, particularly in East Asia. It often affects both knees, even if only one is causing symptoms. It may first show up in a young child as a clunk or in an older child or teenager as pain after sport, and sometimes it is found by chance on a scan in adulthood.

Does it always need treatment?

No. A discoid meniscus that is painless and stable is usually just watched. Treatment is considered when there is pain, swelling, locking, a tear or loss of full straightening. Dr. Gelber sees children and teenagers with discoid meniscus at Aman Hospital in Doha and explains to families when watchful waiting is enough and when surgery may help.