Knock knee - Diagnosing knock knee

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, lie 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 two and four years old and has a gap between their ankles of 10cm (around four 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. A gap of more than 10cm in older children should also be investigated to see if 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.