A Method of Time Prediction in Epiphysiodesis for Limb Length Discrepancy Based On Multiplier

The most critical step in the calculation of final limb length discrepancy (LLD) is estimating the length of the short limb after skeletal maturity(Sm). Paley's multiplier method is a fast, convenient method for calculating Sm and LLD after skeletal maturity; nonetheless, the calculation of the process of Sm and LLD in acquired type cases is complex in contrast to congenital type in this method. Notwithstanding, the multiplier method uses a variable called "growth inhibition" for the calculation process in acquired type LLD; however, its mathematical proof has not been published yet. The present study aims to find out whether there is an alternative way to estimate the length of Sm and LLD in skeletal maturity without using growth inhibition (GI) and its complex calculation process in acquired type LLD.

We used trigonometric equations to prove the GI concept and conducted proportionality analysis to calculate the length of short limbs and LLD in skeletal maturity without using GI.

Based on the results, the following proportionality can estimate the length of the short limb in skeletal maturity. (ΔLm/ΔL = ΔSm/ΔS).

The GI concept can be proved trigonometrically; nonetheless, its numerical value is not necessary for estimating the length of the short limb in skeletal maturity. Instead, a simple proportionality analysis serves the purpose of calculation.