The value of shoe size for prediction of the timing of the pubertal growth spurt

Abstract

Background: Knowing the timing of the pubertal growth spurt of the spine, represented by sitting height, is essential for the prognosis and therapy of adolescent idiopathic scoliosis. There are several indicators that reflect growth or remaining growth of the patient. For example, distal body parts have their growth spurt earlier in adolescence, and therefore the growth of the foot can be an early indicator for the growth spurt of sitting height. Shoe size is a good alternative for foot length, since patients can remember when they bought new shoes and what size these shoes were. Therefore the clinician already has access to some longitudinal data at the first visit of the patient to the outpatient clinic.The aim of this study was to describe the increase in shoe size during adolescence and to determine whether the timing of the peak increase could be an early indicator for the timing of the peak growth velocity of sitting height.

Methods: Data concerning shoe sizes of girls and boys were acquired from two large shoe shops from 1991 to 2008. The longitudinal series of 242 girls and 104 boys were analysed for the age of the "peak increase" in shoe size, as well as the age of cessation of foot growth based on shoe size.

Results: The average peak increase in shoe size occurred at 10.4 years (SD 1.1) in girls and 11.5 years (SD 1.5) in boys. This was on average 1.3 years earlier than the average peak growth velocity of sitting height in girls, and 2.5 years earlier in boys. The increase in shoe size diminishes when the average peak growth velocity of sitting height takes place at respectively 12.0 (SD 0.8) years in girls, and 13.7 (SD 1.0) years in boys.

Conclusions: Present data suggest that the course of the shoe size of children visiting the outpatient clinic can be a useful first tool for predicting the timing of the pubertal growth spurt of sitting height, as a representative for spinal length.This claim needs verification by direct comparison of individual shoe size and sitting height data and than a step forward can be made in clinical decision making regarding adolescent idiopathic scoliosis.

Figure 1

Example of a growth curve of the shoe size of a girl. The start and end of the peak increase of the shoe size are shown as dotted lines. The age at peak increase is shown as the fat dotted line. Age is expressed in years, shoe size in European standards.

Figure 2

Average growth curves of girls and boys from 8-18 years of age. The differences between the timing of peak foot growth velocity based on shoe size and total body height are shown. Growth velocity of total body height is expressed in cm/year and increase in shoe size in shoe sizes/year, both on the same axis. Data concerning growth velocity of total body height are derived from Gerver and de Bruin with permission [5,6].

Figure 3

Example of a growth curve of shoe size of a boy. The curve shows a plateau phase between 13.5 and 15.3 years and again an increase of the shoe size after 15 years. Shoe size is expressed in European standards.