The straight line graph in limb length inequality. A new design based on 182 Dutch children

Moseley's Straight Line Graph (M-SLG), which is based on growth data obtained in the 1940s and 1950s, is helpful for the timing of physiodesis. We investigated whether current growth data could improve this graph. We estimated growth curves based on recent data on 182 Dutch children, collected between 1979 and 1994, using repeated measure analysis of variance. In both boys and girls, the mean femur and tibia length had increased, when compared to the data collected by Anderson et al. (1964). Based on our growth data, a new straight line graph (Rotterdam Straight Line Graph; R-SLG) was created. Its value was assessed by comparing the difference between the predicted length of the short (i.e., not operated) limb at maturity with the final limb length. In a group of 34 children who underwent physiodesis up to 10 years ago, the R-SLG gave better prediction of limb length at maturity than the M-SLG did in 22 of 34 cases and equal results were obtained in 5 cases. We conclude that our updated SLG can improve the prediction of final limb length and thus also the timing of physiodesis.