Knock knees is when there is a gap between the feet and ankles when a child stands with their knees together.

Overview

What are knock knees?

Knock knees, also known as genu valgum, are when a child stands with their knees together but their ankles and feet are set apart.

Cause

This is commonly seen in young children, but it does often correct itself by the time the child turns six or seven. There are underlying conditions that can cause it such as a genetic condition or rickets, where a child doesn’t have enough vitamin D or calcium. Furthermore, obesity can put extra pressure on a child’s knees, which can lead to knock knees.

Diagnosis

A physical exam can help to assess how significant it is. While many children may have a small gap, it is not so normal if the gap between the feet is over 3 inches or 8cm.

Tests may also be done to find out whether there is an underlying cause.

Treatment

As so many children grow out of knock knees, treatment is often not needed. Regular check-ups will be useful to help assess how a child is developing so visits to the clinic are recommended.

Surgery

Should knock knees continue after the age of seven and cause problems for the child, such as knee pain or problems walking, then surgery may be considered. There are different types of surgery that can be options:

• Guided growth: this is where small metal plates are inserted on the inside of the knees. This helps to correct their growth slowly, over the course of a year. Once the treatment is complete and the legs are straight, the plates can be removed in a further operation.
• Osteotomy: a more in-depth procedure and usually not recommended for children unless it is a severe case, the bone has to be broken and fixed in a new, straighter position. Usually, plates and screws are used to hold the bone in the new straight position.

Helpful resources

• NHS: Knock Knees