Leg Length Discrepancy
Patient information for parents and carers — Dr Christopher Spelman, Orthopaedic Surgeon
What is leg length discrepancy
Leg length discrepancy means that one leg is longer than the other. Small differences of up to about one to two centimetres are very common and usually of no consequence – many people have a minor discrepancy without knowing it. Larger differences can affect the way a child walks and stands, and are worth assessing.
Causes
Leg length discrepancy can be present from birth or develop during childhood. Causes include:
Differences present at birth (congenital), sometimes with underdevelopment of a bone
A previous fracture through or near a growth plate
Infection or injury affecting a growth plate
Certain neuromuscular conditions
Some conditions causing overgrowth of one side of the body
In many cases, no specific cause is identified
Assessment
Dr Spelman will assess the discrepancy clinically and, where relevant, with x-rays or specialised imaging that measure the exact difference. Because a child is still growing, an important part of assessment is predicting what the discrepancy will be at the end of growth, using the child’s current measurements and bone age. This prediction guides whether and when treatment is needed.
Treatment
Treatment depends on the predicted final difference. Small discrepancies often need no treatment, or simply a shoe raise for comfort. For moderate discrepancies, a well-timed, minor operation on the growth plate of the longer leg – called guided growth or epiphysiodesis – can slow its growth so that the legs even out by the end of growth. Larger discrepancies may require limb-lengthening or shortening procedures. The timing of surgery is important and relies on careful monitoring of growth.
Outcomes and what the evidence shows
Modern guided-growth techniques (percutaneous epiphysiodesis and plate-based methods) are minimally invasive and are a well-established, effective way to correct moderate discrepancies in growing children, with good results and low complication rates. Accurate prediction of the final discrepancy and correct timing are the keys to success, which is why children with a significant discrepancy are followed regularly until growth is complete.
Complications
The main risks relate to the treatment chosen:
Under- or over-correction – if the timing of an epiphysiodesis is slightly off, the legs may end up not quite equal, occasionally needing a further procedure or a shoe raise.
Angular deformity – uneven slowing of a growth plate can rarely cause the limb to bow if only one side is affected.
Hardware issues – with plate-based guided growth, screws or plates can be prominent or need removal.
Limb-lengthening complications – lengthening procedures are more involved and carry higher risks, including pin-site infection, joint stiffness, delayed bone healing and nerve or blood-vessel irritation.
The general risks of surgery – infection and anaesthetic risks – which are low for the minor guided-growth procedures.
Summary
Small leg-length differences are common and usually need no treatment. For larger differences, accurate prediction of the final discrepancy allows a well-timed, minor guided-growth procedure to even the legs out during childhood, with lengthening reserved for larger differences. Regular follow-up until the end of growth is essential.