Clinical validation of the multiplier method for predicting limb length discrepancy and outcome of epiphysiodesis, part II.

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.