Accuracy of 4 Different Methods for Estimation of Remaining Growth and Timing of Epiphysiodesis.

Background: The calculation of remaining growth in children and the timing of epiphysiodesis in those with leg-length discrepancy (LLD) is most often done with 4 methods: the Green-Anderson, White-Menelaus, Moseley straight-line graph, and multiplier methods. The aims of this study were to identify the most accurate method with use of bone age or chronological age and to evaluate the influence of including inhibition in the calculations.

Methods: One hundred and ninety-one children (10 to 17 years of age) with LLD who underwent surgical closure of the growth plate and were followed until skeletal maturity were identified from a local health register. Patients had at least 2 leg-length examinations with simultaneous bone-age assessments (according to the Greulich and Pyle method), with the last examination performed ≤6 months before surgery. The accuracy of each method was calculated as the mean absolute prediction error (predicted leg length - actual leg length at maturity) for the short leg, the long leg, and the LLD. Comparisons were made among the 4 methods and among calculations made with chronological age versus bone age and those made with versus those without incorporation of a reduced growth rate (inhibition) of the short leg compared with the long leg.

Results: The White-Menelaus method with use of bone age and a fixed inhibition rate was the most accurate method, with a prediction error of 1.5 ± 1.5 cm for the short leg, 1.0 ± 1.2 cm for the long leg, and 0.7 ± 0.7 cm for the LLD. Pairwise comparison of short-leg length and LLD according to the White-Menelaus and other methods showed that they were significantly different (p ≤ 0.002). The calculated inhibition rate did not increase accuracy.

Conclusions: The White-Menelaus method used with bone age and constant inhibition should be the preferred method when predicting remaining growth and the timing of epiphysiodesis in children between 10 and 17 years of age. One examination is in most cases sufficient for the preoperative clinical investigation when chronological age and bone age are concordant.

Level of evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.