Limb Length Discrepancies
A small difference in arm or leg length is very common, but a larger difference in length can affect mobility and quality of life. A limb length discrepancy might be caused by a previous injury to the bone or growth plate, a bone infection, a bone disease or underdeveloped bones at birth.
Because the risks may outweigh the benefits, we do not usually recommend surgery to equalize leg lengths if the difference is less than 1 inch. For these small differences, we typically recommend a shoe lift. Your child’s orthopaedic specialist can help your family with an appropriate shoe lift.
For young children who still have a lot of growth ahead, we use external fixation to lengthen the shorter leg. A scaffold-like frame is surgically placed on the outside of the leg and connected to the bone through small wires or pins. A small crack is made in the bone and the frame creates tension when the dial is turned. This is done several times each day. The bone may lengthen 1 millimeter per day, or about 1 inch per month. The external fixator is worn until the bone is strong enough to support the child safely, which usually takes about three months for each inch.
In adolescents, we use the new variable diameter PRECICE® Nail system to lengthen a leg. We remove a small amount of bone from the shorter leg and implant a telescopic rod. An external magnet is then placed on the skin several times a day to lengthen the rod gradually. New bone will eventually fill in the gap. The process takes about six weeks of lengthening, followed by six weeks of recovery on crutches.
In some cases when the length difference is small, your child’s doctor may recommend slowing the growth of the longer leg. This procedure involves making small incisions around the knee to stop the leg’s growth. There will not be an immediate correction in length, but the opposite limb will continue to grow and catch up over time. Our doctors have the ability to predict remaining growth so that the proper corrections are made. The goal is to reach equal length by the time growth normally ends in the mid-to-late teenage years.
Orthopedic physical therapy is critically important for children undergoing limb lengthening procedures. When a limb is lengthened, the bone, muscles and surrounding soft tissue must lengthen with it. At CHOC, our physical therapists have special training in limb rehabilitation and know the proper techniques for ensuring a child’s recovery, as well as for preventing injuries such as fractures, nerve damage and muscle contractures.
Depending on a doctor’s orders and the patient’s needs, a physical therapy program may be as often as five times per week, for six to nine months, until a child returns to his or her normal activities. Sessions may include land therapy or pool therapy to address pain and issues such as weakness, tightness and instability. CHOC child life specialists and pet therapy volunteers may be available to help put children more at ease as they progress through their therapy program. A home exercise program is also prescribed to build on the progress made in therapy and ensure a good recovery.