Timing of Epiphysiodesis to Correct Leg-Length Discrepancy: A Comparison of Prediction Methods

SLR - October 2018 - Kristopher P. Jerry

Methods: According to this article, there are four main methods of estimating leg-length inequality at maturity and the timing of epiphysiodesis for treatment: the arithmetic method proposed by White and Stubbins (modified by Menelaus), the growth-remaining graphs of the distal end of the femur and proximal end of the tibia described by Anderson et al, the straight-line graph method proposed by Moseley and the multiplier method described by Paley et al.  

In this retrospective study, 77 patients who had been treated with epiphysiodesis for the management of leg-length inequality with adequate preoperative radiographs, no postoperative complications and follow-up to skeletal maturity composed the study group. These patients had previously undergone epiphysiodesis of the distal part of the femur and/or the proximal part of the tibia. They compared the predicted lengths of both legs and residual leg-length discrepancy at maturity with actual outcomes using the White-Menelaus, Anderson-Green, Moseley and multiplier methods.         

Results: The authors stated that the short leg length and leg-length discrepancy prediction accuracy of each method was improved by using skeletal, rather than chronological, age. Skeletal age varied >1 year from chronological age in 61 of 231 observations, including 19 patients whose average skeletal age from three determinations differed by >1 year from chronological age. Error in prediction of the length of the short leg varied from a mean of approximately 1.8 cm for the straight-line graph to 2.5 cm for the multiplier method. Prediction error for the long leg (after epiphysiodesis) varied from a mean of about 1.2 cm for the straight-line graph to 1.7 cm for the multiplier method. Leg-length discrepancy prediction error ranged from a mean of approximately 0.7 cm for the White-Menelaus method incorporating a growth inhibition factor to 1.1 cm for the multiplier method. The multiplier method was the least accurate of all, and all differences were significant.

Conclusions: In this study, the authors determined that the use of skeletal age, instead of chronological age, on average improved the accuracy of the four prediction methods that they evaluated. The authors state that the Rotterdam straight-line graph and the White-Menelaus methods were significantly superior in the prediction errors of the length of both legs at maturity. All methods were clinically and statistically comparable in predicting leg-length inequality at maturity. However, the multiplier method was the least accurate method of predicting the lengths of the long and short legs in this study. The authors therefore recommend caution when using the Multiplier method and that the leg-length and epiphysiodesis timing predictions be based on skeletal age.