Correction of leg length differences and deformity using the circular external fixator has been very helpful for this problem. Establishing (or recreating) normal length and alignment of both legs are the goals.
Radiographic imaging using X-rays is the best way to confirm that everything is placed correctly. X-rays are taken to show if everything is lined up and coming along properly. The surgeon relies on this information to know when and how much to adjust the cage to lengthen the leg. The cage is adjusted to lengthen the leg slowly.
The images provided by the X-rays give the surgeon information needed to evaluate alignment, rotation, and length of the lower extremity. Full-length standing radiographs are taken with and later, without the fixator.
The X-rays can be analyzed to show if optimal alignment has occurred. Some places have computerized equipment that takes all the measurements and makes necessary calculations. While the fixator is in place, adjustments can be made.
Future computer and imaging technology may make it possible to mathematically predict changes in the leg length. X-rays may be taken much less often to confirm corrections made. But for now, an optimal result requires careful follow-up.