Limb length inequality is defined by one leg being longer than the other in a patient of any age. The goal for treating a growing child is to correct the difference as it will exist at maturity (when the child is done growing) and not to correct the difference that is currently present in the child.

The problems that can be associated with a leg length inequality include: risk of arthritis in the knee, hip, or spine; increased energy expenditure for walking and running; and cosmetic abnormalities. Children tolerate limb inequalities better than adults and will walk on their toes or bend the long leg’s knee to walk more normally. Unfortunately, this becomes harder and harder to do as one gets older.

The important thing to determine in a growing child is whether this discrepancy is staying the same length as the child becomes older or if the difference is getting larger. Sometimes x-rays made periodically over time are required to determine if this is the case. Also, if a leg length inequality is identified, the patient will need an x-ray called a “Bone Age”. This is an x-ray of the hand that will be used to determine the relative age of a child’s bones (degree of skeletal maturity) compared to other children of the same age.

What are the treatment options?
Treatment is decided based upon how much difference is expected to be present when the child is done growing. All people have some difference in limb length, normally less than 1 centimeter between legs. (There are 2½ centimeters in one inch). If the predicted difference in limb lengths at skeletal maturity is less than 2 centimeters, treatment is conservative (close observation or shoe inserts if they are having pain or walking problems). If the difference is between 2 and 6 centimeters, then either a shoe lift (on the outside of the shoe) or an epiphyseodesis (slowing the growth on the longer side so that the shorter side can catch up) is appropriate. When the difference is between 6 and 20 centimeters, then combinations of different procedures are typically required, including lengthening the short side and shortening the longer side. If the difference measures more than 20 centimeters when they are done growing, a prosthesis may be the best answer.

Fortunately, most people have a discrepancy which is treatable by either an insert into the shoe or a lift on the outside of the shoe. Shoe inserts are limited to 2 centimeters to prevent the foot from sitting too high and popping out when walking. A shoe lift works well for differences between 2 and 5 centimeters, but if it is more than that, the patient may have problems ankle injuries.