While many people have slight differences in the length of one leg compared to the other, a significant difference between the two legs can cause problems. Leg length discrepancies can disturb the way a person walks, how his or her spine lines up and strain hip joints.
Some children are born with absence or underdeveloped bones in the lower limbs e.g., congenital hemimelia. Others have a condition called hemihypertrophy that causes one side of the body to grow faster than the other. Sometimes, increased blood flow to one limb (as in a hemangioma or blood vessel tumor) stimulates growth to the limb. In other cases, injury or infection involving the epiphyseal plate (growth plate) of the femur or tibia inhibits or stops altogether the growth of the bone. Fractures healing in an overlapped position, even if the epiphyseal plate is not involved, can also cause limb length discrepancy. Neuromuscular problems like polio can also cause profound discrepancies, but thankfully, uncommon. Lastly, Wilms? tumor of the kidney in a child can cause hypertrophy of the lower limb on the same side. It is therefore important in a young child with hemihypertrophy to have an abdominal ultrasound exam done to rule out Wilms? tumor. It is important to distinguish true leg length discrepancy from apparent leg length discrepancy. Apparent discrepancy is due to an instability of the hip, that allows the proximal femur to migrate proximally, or due to an adduction or abduction contracture of the hip that causes pelvic obliquity, so that one hip is higher than the other. When the patient stands, it gives the impression of leg length discrepancy, when the problem is actually in the hip.
Back pain along with pain in the foot, knee, leg and hip on one side of the body are the main complaints. There may also be limping or head bop down on the short side or uneven arm swinging. The knee bend, hip or shoulder may be down on one side, and there may be uneven wear to the soles of shoes (usually more on the longer side).
There are several orthopedic tests that are used, but they are rudimentary and have some degree of error. Even using a tape measure with specific anatomic landmarks has its errors. Most leg length differences can be seen with a well trained eye, but I always recommend what is called a scanagram, or a x-ray bone length study (see picture above). This test will give a precise measurement in millimeters of the length difference.
Non Surgical Treatment
Whether or not treatment should be pursued depends on the amount of discrepancy. In general, no treatment (other than a heel life, if desired) should be considered for discrepancies under two centimeters. If the discrepancy measures between two and five centimeters, one might consider a procedure to equalize leg length. Usually, this would involve closure of the growth plate on the long side, thereby allowing the short side to catch up; shortening the long leg; or possibly lengthening the short leg.
Bone growth restriction (epiphysiodesis) The objective of this surgical procedure is to slow down growth in the longer leg. During surgery, doctors alter the growth plate of the bone in the longer leg by inserting a small plate or staples. This slows down growth, allowing the shorter leg to catch up over time. Your child may spend a night in the hospital after this procedure or go home the same day. Doctors may place a knee brace on the leg for a few days. It typically takes 2 to 3 months for the leg to heal completely. An alternative approach involves lengthening the shorter bone. We are more likely to recommend this approach if your child is on the short side of the height spectrum.