Knock knee - Treating knock knee

In most cases, knock knee does not need to be treated, because the abnormal curvature of the lower legs corrects itself as a child grows.

In young children (up to four years old), a gap between the ankles of 10cm (around four inches) or less is not usually a cause for concern. It will often correct itself by the time the child is six or seven years old.

If the distance between your child’s ankles is greater than 10cm, you should take your child to see a GP so that the underlying cause can be investigated (read more about diagnosing knock knee).

Treating underlying conditions

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, also known as osteomalacia (soft bones), is a rare condition that is often caused by a lack of vitamin D. This plays an essential role in the development of strong and healthy bones.

Rickets can be treated using regular (daily) vitamin D supplements or a yearly vitamin D injection. It also helps to eat a diet rich in calcium and vitamin D.

Surgery

In rare cases, corrective surgery is used to treat severe cases of knock knee. It is usually only recommended when the gap between a child’s ankles is greater than 10cm and their lower legs are severely curved, resulting in knee pain or difficulty walking.

The surgical procedure used may be either:

guided growth – placing a small plate on the inside of the knee that gradually corrects the growth of the knee over six to 12 months
an osteotomy – cutting and realigning the leg bone to correct the angle of the knee and redistribute the weight going through it

Guided growth is usually preferred for children up to around 14-16 years old, as they are still rapidly growing.

What happens during an osteotomy?

The operation needs to be carried out on each leg at different times, so that the weight can be kept off the leg that has been operated on while it heals.

Before the surgery, a full-length X-ray of both legs will be taken so that the hips, legs, knees and ankles can be closely examined and the amount of realignment that is needed can be assessed.

In some cases, when the knee joint is thought to be severely damaged, further investigations such as a magnetic resonance imaging (MRI) scan or an arthroscopy (keyhole surgery) may also be required.

A distal femoral osteotomy is carried out in hospital, and your child will usually need to stay in for one or two days. The operation is carried out under general anaesthetic, which means they will be asleep throughout the procedure and unable to feel any pain.

During the operation, the lower end of the upper leg bone (the femur) is cut just above the knee joint, and a small wedge of bone is removed. This allows the leg to be realigned to create a more normal, straighter position. A plate and screws are used to fix the leg bone in its new position.

After the operation, the knee has to be kept still and straight using a splint (support), which will usually need to be worn for about five to six weeks. Crutches will also need to be used during this time to keep the weight off the leg that has been operated on.

It will usually take about three months for the leg to fully heal. During this time, physiotherapy may be recommended to help improve the mobility of the knee and aid recovery.

After around three months, any knee pain should be significantly reduced, and your child’s mobility should be improved.

Important advice for adults

If you need surgery and you smoke, it is very important that you do not smoke for at least two weeks before the operation and for a minimum of three months afterwards. This is because the effects of smoking restrict the blood supply to the bone, which can prevent or delay the wound from healing.

You should be able to drive six to eight weeks after having a distal femoral osteotomy.