Leg length discrepancy

Specific treatment for leg length discrepancy will be determined by your child's orthopedic surgeon based on

• your child's age, overall health, and medical history
• the extent of the discrepancy
• your child's tolerance for specific medications, procedures, or therapies
• expectations for the course of the condition
• your opinion or preference.

You and your child's feelings about the treatment are extremely important. Some techniques used to equalize leg length are simple and safe, but others, especially lengthening procedures, are complex with high complication rates. These require strict cooperation by you and your child for success.

Much planning is involved in the early stages of managing a child with a leg length discrepancy.

• Since children are still growing, the goal of treatment is to correct the discrepancy that would be present at maturity and not the present discrepancy.
• Not all children grow at the same rate, so careful analysis of your child's personal rate of growth is crucial.
• To estimate the discrepancy at maturity, your child's orthopedic surgeon may need to continually take measurements of your child's growth over a period of one or two years before any surgery can be considered.

The goal of treatment is not always to have legs of equal length. For example, some patients, with neuromuscular conditions that involve muscle weakness or paralysis of the short leg, may do best with an under-correction of one or two cm. This slight discrepancy allows for clearing of the floor during the swing phase of the walking cycle.

Generally speaking, discrepancies greater than two cm at skeletal maturity usually require some kind of intervention, because these will cause limping.

Non-surgical treatment

• Orthotics - shoe lift can be used to treat discrepancies from two to six cm.
• Prosthetics – these devices, which are typically used to treat a child who has had to have an amputation, may be satisfactory for some patients with very large discrepancies, who would not benefit from other lengthening or shortening procedures.

Surgical treatment

Shortening procedures - The following procedures, used to shorten the longer leg, may be recommended for some children, in cases where the leg length discrepancy is expected to be between two and six cm at maturity. Shortening is considered safer and results in fewer complications than lengthening procedures:

• Epiphysiodesis - This procedure slows the rate of growth of the long leg, allowing the short leg to catch up. The operation involves the creation of bony ridge, usually by repositioning a block of bone in the region that tethers the growth plate, preventing future growth. The disadvantages of this procedure include shortened stature, surgery on the unaffected extremity, and the irreversibility of the procedure.
• Epiphyseal stapling - This operation is performed to slow the rate of the growth temporarily. Staples are surgically inserted on each side of the growth plate. Once equalization has been achieved, the staples are removed.
• Bone resection - This operation, removal of a section of bone to equal out the discrepancy, can be performed in adults or adolescents who are no longer growing.

Lengthening procedures - are usually reserved for discrepancies that are more than four cm. While one of the obvious advantages of lengthening is the achievement of a desirable height, it is not always the method of choice because the process used is technically difficult and has a significant rate of complications, discussed further below.

A customized apparatus that encircles the leg is surgically attached to the limb that will be lengthened by pins. Limb lengthening correction works on the principle of bone regeneration (osteogenesis) as segments of the bone are pulled apart (distracted).

• To achieve this, a bone is first cut in two during surgery.
• Days after surgery, the two ends of the bone are very gradually pulled apart through continual adjustments that are made to the apparatus, usually at a rate of one mm per day. This gradual distraction leads to formation of new bone between the two ends, at the site of lengthening.
• After the process in complete, and the bone is given a chance to harden, the apparatus is surgically removed.
• A cast or brace may be required for some time for further protection.

Common complications associated with lengthening procedures include

• pin tract infection
• wound infection
• hypertension
• partial dislocation of the hip and knee
• a delayed union of the bone and fatigue fractures after removal of the lengthening apparatus.

Physical therapy, designed to stretch muscles and maintain joint flexibility, is an important component to any surgeries used to correct leg length discrepancies. With proper treatment, your child will be able to resume all their normal activities.