Guided growth surgery for lower limb deformity

Bow legs is a condition which most children have and later grow out of. Consultant paediatric orthopaedic surgeon, Mr Thomas Crompton, explains the causes of this condition and the treatment options for those who don’t grow out of it.

What are bow legs?

Bow (or bowed) legs, or genu varum, is the term used to describe when a person's legs curve outwards from the ankle, at an angle which resembles a bow. When children are learning to stand and walk, between the ages of 18 months and 2 years, it’s very common for their knees remain far apart, curving away from each other when their feet touch, which causes the bowed appearance. This is very normal, with the majority of young children experiencing this in their first two years. Many children later experience knock knees (genu varum), which is when the legs bend inwards, causing the knees to knock together.

Cause

Both conditions are seen as a normal part of young children’s growth, although they can sometimes occur as a result of another condition or deformity. Therefore, if your child has bow legs or knock knees, it’s important to visit an orthopaedic specialist to be sure of the cause.
Genetic factors or rickets, a condition in which a calcium or vitamin D deficiency affects bone development, can also cause either condition. Obesity can also be a cause, due to the extra stress placed on a child’s knees which forces them to bend inwards or outwards.

Diagnosis

Diagnosis is usually fairly straightforward and can be reached through clinical examination. X-rays can be used to provide further clarity and monitor progress, while other tests may be necessary if there is believed to be an underlying cause like rickets or obesity.

Treatment

A large proportion of children with bow legs or knock knees simply grow out of it as the bones develop, so treatment is often not necessary. Regular check-ups to assess how the child is developing are usually enough.

Surgery

Knock knees and bow legs become problematic if they continue after the age of seven, especially when they cause knee pain and difficulty or pain when walking. In these cases, one of the following surgery options may be considered:

• Guided growth: This is where growth is corrected slowly through the use of small metal plates which are surgically inserted around the knee. This process takes around a year, after which the plates are surgically removed.
• Osteotomy: This is a more thorough procedure where the bone is broken and then fixed and aligned correctly, before being held in place by plates and screws. This procedure is usually not recommended for children, unless it is an extreme case.
• Guided growth with PediPlates can also be used to temporarily reduce growth if one leg is longer than the other. There are many reasons for a leg length discrepancy including trauma and infection. Some children are born with it, while others, have no known cause. Depending on the size of the discrepancy, and the amount your child has left to grow we can use guided growth to correct the leg lengths.

For children with a larger discrepancy or those not wanting to lose too much height we can lengthen limbs also. You can find further details on limb lengthening here.

For further consultation on this or any other orthopaedic issue, you can request an appointment with Mr Crompton by visiting his Top Doctors profile.