The Fels Method

The Fels method was developed by Roche through a longitudinal study, based on a total of 13,823 serial X-rays of the left hand and wrist. These images were performed in 355 male and 322 female children born between 1928 and 1974, from the first month of life up to the age of 22 years (124). Data obtained in this study were introduced in a computerized system that analyzes 111 maturity indicators of the hand and wrist area in relation to sex and age, morphology, contiguity ratios, and through linear measurements of some bone segments (125, 126). For the Fels method, the prediction of adult height is calculated with the Roche–Wainer–Thissen formula. Although this method is very accurate and allows doctors to estimate children's bone age even when they are <1 year old, the Fels method is too complex, thus minimizing its daily use.