Knock knee - Diagnosis 

Diagnosing knock knee 

Your child’s legs and feet

You should seek advice from your GP if you have any concerns about the development of your child's legs or feet.

Read more about leg and foot problems in children.

You can assess the extent of your child’s knock knee by measuring the distance between their ankles when their knees are together.

To measure the distance between your child’s ankles, lay them on their back and straighten out their lower limbs. Place their knees together and measure the distance between the insides of their ankles.

If your child is between 2-4 years of age and has a gap between their ankles of 10cm (4 inches) or less, it will usually correct itself as your child grows. If the gap is greater than 10cm, you should take them to see their GP. In older children, a gap of more than 10cm should also be investigated to determine whether there is an underlying problem.

As well as the distance between your child’s ankles, your GP may also assess your child’s:

  • height
  • knee symmetry (how even the knees are)
  • leg, hip and feet alignment
  • gait when they walk (to check whether they can walk normally)

Your GP may refer your child to an orthopaedic surgeon (a doctor who specialises in muscle, bone and joint disorders or injuries). Your child may need to have an X-ray to help identify any underlying problems that are causing knock knee.

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Last reviewed: 17/01/2012

Next review due: 17/01/2014

Child health 6-15

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