The Ilizarov technique
The Ilizarov technique relates to the use of a circular external fixation frame designed in the 1950s by Gavril Abramovitch Ilizarov in Siberia. The revolutionary principle he discovered was that bone can be cracked and when it starts to heal the crack can be stretched slowly (at about 1 millimetre per day) to lengthen it. This means that missing segments of bone can be re-grown, and leg length restored after injury.The frames themselves rely on either stiff pins running from the frame into the bone, or thin wires that pass through the bone, and are attached at each end to a ring around the leg under high tension, making them very rigid. Unfortunately, although the bone is stretched at 1mm per day, it takes a further 3 or 4 days of ‘consolidation’ to become solid enough to allow removal of the frame, giving a total of 4 or 5 days in a frame for each millimetre of bone re-grown. The technique has been expanded by the use of more modern external frames such as the Taylor Spatial Frame, which allows correction of multiple deformities simultaneously including angulation, rotation and shortening. The deformity is programmed into a computer, and the software calculates the necessary frame adjustments to allow for millimetre perfect accuracy. It can be further adapted in a few situations to allow lengthening over intramedullary rods within the hollow centre of the bone. This has the advantage of dramatically shortening the time the frame is needed, and is particularly useful in bones such as the femur (thighbone) where an external fixator is bulky and awkward.