Guided Growth for Limb Deformity

Also known as: Hemiepiphysiodesis, Growth modulation, Tension band plating, Eight-plate, Bowed legs, Knock knees

In a child who is still growing, a crooked leg can often be straightened without cutting bone. A small implant slows growth on one side of the growth plate, and the limb straightens itself over months.

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The principle

Long bones grow from a plate of cartilage near each end. If growth on one side of that plate is slowed while the other side carries on, the bone gradually bends in the opposite direction. Straightening a limb becomes a matter of putting a small implant across one side of the plate and waiting.

The implant is usually a two-hole plate with a screw on either side of the growth plate, working as a tension band. The growth plate itself is not drilled or damaged, which is what makes the procedure reversible.

This is a slow correction. Nothing is forced. The child's own growth does the work.

What it treats

Genu valgum, knock knees
Genu varum, bowed legs, including Blount disease
Ankle valgus, which is common in children with spina bifida, skeletal dysplasia or a previous fracture
Deformity after trauma or infection that has damaged part of a growth plate
Deformity in neuromuscular conditions and in skeletal dysplasias
Leg length discrepancy, by slowing the whole growth plate of the longer leg rather than one side

Who it suits

The single requirement is remaining growth. Without it the technique cannot work. Deciding this properly needs more than the child's age:

Bone age, from a radiograph of the left hand and wrist, which is often a year or more away from calendar age
Standing full-length alignment radiographs of both legs, taken with the kneecaps facing forward
Growth remaining, estimated against the child's growth chart and pubertal stage
The magnitude of the deformity, and whether it is getting worse

A child close to skeletal maturity with a large deformity does not have enough growth left, and an osteotomy is the honest recommendation.

The operation

A day-case procedure through an incision of two to three centimetres on the side of the knee or ankle. The plate is positioned under radiographic guidance and fixed with two screws. There is no plaster in most cases, and the child walks the same day.

What follow-up looks like

This is the part that decides the result. The child is reviewed every three to four months with a standing alignment film, and the correction is measured each time. When the leg is straight, the implant comes out. Not before, and importantly not long after.

Overcorrection from leaving the plate in too long is the commonest complication of guided growth, and it is a follow-up failure rather than a surgical one. Families who cannot commit to regular review should be told plainly that this technique is not a good fit for them.

Typical recovery after surgery

A typical course. Your own plan is set at your visit and depends on the operation.

Day 0 to 1Day case or one night in hospital. Walking the same day, usually without a cast.
Week 2Wound check. Back at school. No restriction on normal walking.
Week 6Return to sport, including contact sport in most cases.
Every 3 to 4 monthsClinic review with a standing alignment radiograph, to watch the correction happen.
12 to 24 months (variable)Once the leg is straight the implant is removed in a second short operation. Timing this correctly is the whole art of the procedure.

Common questions

How is this better than breaking and resetting the bone?

It is a far smaller operation. No bone is cut, there is no plaster, the child walks the same day and is back at sport within weeks. An osteotomy corrects immediately but involves cutting bone, a longer recovery and more risk. Guided growth is slower, but where the child has enough growth left it achieves the same alignment for a fraction of the cost to the child.

How long does the correction take?

It depends on how much growth the child has left and how much correction is needed. Around the knee the alignment often changes by roughly a degree a month, so most corrections take somewhere between nine months and two years. Younger children correct faster.

What happens if the plate is left in too long?

The leg keeps correcting and overshoots into the opposite deformity. This is the main pitfall of the technique, and it is entirely avoidable with regular review. The follow-up appointments are not optional; they are how the operation is steered.

Does my child need the implant removed?

Yes, once the alignment is correct. Removal is a short day-case procedure. After removal, growth resumes normally on both sides.

Can the deformity come back after removal?

In a young child with a lot of growth remaining, yes, it can slowly recur, and the plate can be reinserted. This is why the child is followed until skeletal maturity rather than discharged after removal.

Are bowed legs or knock knees normal in a toddler?

Very often, yes. Bowing is normal up to around the age of two, and knock knees are normal between about three and six, both correcting on their own. Assessment is warranted when the deformity is severe, only on one side, getting worse rather than better, outside the usual age range, or the child is short for their age.

This page is for patient information and does not replace an examination by a doctor.