Limb length inequality is a fairly common occurrence. It is estimated that about one in four people have at least a one-centimeter difference in leg length (about one-half inch) from one side to the other. However, sometimes the difference is enough to warrant surgical correction.
A new technique called the Ilizarov procedure has made it possible to lengthen the short side without using a bone graft or plate fixation. The cortex of the bone (outer portion) is cut in two leaving the blood vessels intact. This part of the procedure is called a corticotomy.
A circular cage or fixator is then attached through the skin to the bone with tension wires and/or pins. The Ilizarov fixator applies gradual tension by slowly distracting the soft tissues and bone. New bone, skin, blood vessels, nerves, and muscles gradually form and fill in the distraction gap.
When a bone callus has formed (but before solid bone develops), the fixation device is slowly lengthened to distract the two ends of the bone just a little bit more.
This process of low energy gradual distraction-lengthening is repeated until the limbs are equal in length and complete bone healing has occurred.
Correction usually takes between four and 12 months. During the long recovery period, regular follow-up visits with the surgeon are required. Frequent adjustments are made to the frame. Bone healing is gauged based on X-rays. Some surgeons are investigating the use of an Orthometer to measure bone healing and stiffness after lengthening.
This device is used quite effectively in adults but has not been standardized to use in children. When safe values are determined, this tool may be used to determine when it is safe to remove external fixation in children with pins, plates, screws, or cages for healing of fractures, fusions, or limb lengthening.