Introduction 

Knock knee is an abnormal curvature of the lower legs, resulting in a large gap between the feet and ankles when the knees are touching.

The medical name for knock knee is genu valgum.

Most children have bow legs until they are around three years old, as a result of the legs being folded inside the womb. They are "knock kneed" at around four or five years of age. The legs begin to straighten and align normally by the time they are six or seven.

However, in some children, knock knee continues, or it occurs at a later stage of development. In these cases, the cause is often unknown, although knock knee can be caused by bone conditions, such as rickets or scurvy. It may also be the result of an inherited bone deformity.

Read more about the causes of knock knee.

What are the symptoms of knock knee?

Most cases of knock knee do not cause any significant problems, and the child's legs will straighten on their own by the time they are about six or seven.

If knock knee persists, or if there is a significant deformity, the child may have difficulty walking or walk awkwardly. Unnecessary strain on their knees may also lead to knee pain.

Read more about the symptoms of knock knee.

Treating knock knee

If your child’s knock knee is caused by an underlying condition, such as rickets or scurvy, the condition will need to be treated. Rickets can be treated with vitamin D and calcium supplements, and scurvy can be treated with vitamin C supplements.

Corrective surgery may be recommended in cases where knock knee is the result of an inherited bone deformity and is causing severe knee pain and problems walking.

There are several different surgical techniques that can be used, but a procedure known as an "osteotomy" is most commonly used. This involves cutting and re-aligning the lower part of the upper leg bone (femur) to correct the position of the leg and re-distribute the weight going through the knee.

Read more about how knock knee is treated.

Knock knee is abnormally curved legs, which cause a gap between the feet and ankles when the knees are together   

Services and support for parents

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Page last reviewed: 06/03/2014

Next review due: 06/03/2016