Ask the Expert: Dr. Austin Fragomen, Limb Lengthening Surgeon, Answers Your Questions About Limb Lengthening
Q1: What is the amount of difference between limbs where it becomes useful to lengthen? I have a one inch difference between my leg lengths and back in the 80s was told it wasn’t enough to intervene. Just curious as it hasn’t really caused too many problems…yet.
This varies between people. Some patients tolerate 2cm of limb length discrepancy and others are very symptomatic with a 1cm difference. However, I typically use 1cm as a cut off for lengthening. One inch (2.5cm) is a significant difference. This could lead to low back problems including scoliosis over time. You should use a shoe lift to correct most if not all of the shortening. If you are comfortable with the lift on the shoe, you can either continue to use the lift or look into a permanent solution (limb lengthening).
Q2: What is the longest limb lengthening? And how long does it take for the bones to mature completely?
The longest limb lengthening, meaning the greatest number of centimeters a bone has been lengthened, is over 25cm. These large lengthenings occur in cases of trauma where the leg is mangled and there is tremendous bone loss or missing bone. The goal is to restore the original length of the bone. In the case of stature lengthening (making someone taller) the longest lengthenings are in patients with skeletal dysplasia (dwarfism/little people) and are on the order of one foot if we include both femur and tibia. The bones heal at the rate of one and half to two months per centimeter of length, roughly.
Q3: Can both a femur and tibia be lengthened at the same time?
Yes but with caution. Pioneers in limb lengthening attempted heroic lengthening of both femur and tibia simultaneously and found that the knee joint was injured in some cases. In children, the natural growth from the growth plates around the knee can be suppressed when both tibia and femur are lengthened too much at the same time.
Q4: How long does the entire process take for legs? When can you go back to walking?
This is an exciting question because at Hospital for Special Surgery we are developing novel techniques to drastically reduce the duration of the lengthening process. Classically the process duration is directly related to the amount of length achieved. A 5cm (2 inch) lengthening would require the patient to wear an external fixator for eight months. However using our LATN or LAP technique the “time in the frame” is reduced to two to three months total! Walking is encouraged right after surgery. It has been shown that early weight bearing speeds bone healing and muscle function.
Q5: Is it better to consider limb lengthening as a child or adult?
It is always better to look into options earlier. There is no sense in making a child with a short leg or arm wait until maturity to be evaluated by a fellowship trained limb lengthening expert. The sooner the patient is evaluated the more options one generally has to choose from.
Q6: Could a difference in leg length be attributed to or confused with other causes?
Yes, some common conditions might make a patient appear to have a limb length difference. Scoliosis or twisting of the spinal column causes the pelvis to tilt obliquely. This pelvic tilting raises one hip higher than the other. It then appears that one leg is shorter. An x-ray will clarify this misconception. Tightening of the hip adductor muscle on one side (common with stroke or cerebral palsy) will cause pelvic tilting as well and give the same effect. A flatfoot on one side will cause shortening of the foot and apparent leg length discrepancy. The best way to know whether you have a true leg length discrepancy is to see a limb lengthening expert for an evaluation.