A graphic method for timing the correction of leg-length discrepancy.

We have developed a clinical method for the graphic recording, analysis and planning of treatment of leg-length discrepancy during growth. Initially, the clinically determined discrepancy is plotted against the chronological age yearly, and then in late childhood at six-monthly intervals. CT and measurements of skeletal age are made in middle and late childhood to confirm the clinical findings. In a prospective study in 20 children, we observed that only eight had a linear increase in discrepancy. The observed pattern of increase was therefore used to estimate the mature discrepancy. Epiphyseodesis reference slopes were used to determine the most appropriate time and type of epiphyseodesis. In all children, the leg-length discrepancy at maturity was within 1 cm of the predicted amount. Changes in discrepancy due to leg lengthening or correction of deformity were also plotted graphically. We conclude that the clinical graphic method is simple to use, takes into account the varying patterns of discrepancy, and minimises radiation dosage.