My child's knee clunks and won't fully straighten. Should I worry?

What parents usually notice

• A visible or audible clunk or snap as the knee straightens or bends, often on the outer side
• The knee never quite straightening when the child stands or lies down
• Pain on the outer side after football, running or play
• Limping, swelling or the knee getting stuck from time to time

Some children have had the clunk for years without pain, and parents only seek help when it starts to hurt or catch.

Why a discoid meniscus clunks

A normal meniscus is C-shaped. A discoid meniscus is fuller, more like a disc, and is usually on the outer, lateral side. It can be less firmly attached, so it shifts as the knee moves and snaps back into place with a clunk. Its thickness can also stop the knee straightening fully. Because the tissue is abnormal, it tears more easily, even without a clear injury.

Other causes to consider

Clicking that is painless and quiet, usually from the kneecap, is common and often harmless in children. A painful knee in a child can also come from Osgood–Schlatter disease, osteochondritis dissecans or, at the hip, problems that refer pain to the knee. Seek urgent care if your child has a fever with a hot, swollen knee, cannot bear weight, or has severe night pain.

What a visit involves

At Aman Hospital in Doha, Dr. Gelber examines both knees, as a discoid meniscus can be present on both sides, watches how your child walks and squats, and checks the hip. X-rays and an MRI may be advised. Many children with a painless clunk only need monitoring, while those with pain, locking or a tear may benefit from keyhole surgery.