To validate the accuracy of the multiplier method in predicting limb length discrepancy (LLD) and outcome of epiphysiodesis, radiographs of 60 patients treated for LLD were measured. Data generated were used to predict maturity lengths of epiphysiodesed limbs, bone length discrepancies at maturity, and LLD at maturity after epiphysiodesis (residual discrepancy) using the multiplier and Moseley methods. The multiplier method mean error for bone length discrepancies predictions was 0.6 cm (SD = 0.6). Mean error for predicting lengths of epiphysiodesed limbs was 1.6 cm (SD = 1.2) for both methods. Mean errors for predicting residual discrepancies were 0.9 cm for the multiplier method using chronologic age, 1 cm for the multiplier method using skeletal age, and 1.3 cm for the Moseley method. Mean error difference between the methods was significant (P = 0.0008). The multiplier method accurately predicts LLD and outcome of epiphysiodesis and is more accurate than the Moseley method in predicting LLD at maturity after epiphysiodesis.

To validate the accuracy of the multiplier method in predicting bone and limb maturity lengths, radiographs of 60 patients treated for lower limb length discrepancy were measured. Longitudinal limb length data were used to predict maturity lengths of non-epiphysiodesed normal bones and short bones. Mean errors for predictions were 1.1 cm (SD = 0.9) and 1.5 cm (SD = 1.3) for the multiplier method using chronologic age and skeletal age, respectively. Regression correlation values between multiplier method predictions and actual measurements were 0.93 using chronologic age and 0.90 using skeletal age. The multiplier method was more accurate than prediction using the Anderson et al growth charts. Mean error for limb length predictions was 2.5 cm for the multiplier method using chronologic age and 2.6 cm for the Moseley method. Although as accurate as the Moseley method, the multiplier method seems to be quicker and simpler to use and requires only one data point for predicting limb length at maturity.

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