TW3 and Fels skeletal ages in elite youth soccer players

Background: Skeletal age ( SA) tends to be advanced for chronological age ( CA) in adolescent male soccer players. Aim: The study compared SA assessments with the TW3 and Fels methods in a sample of male, elite youth soccer players. Methods: SAs were assessed with the Tanner-Whitehouse 3 ( TW3) radius-ulna-short bone (RUS) and Fels methods in a sample of 40 elite youth soccer players 12.5-16.1 years of age. Players were classified as late, on time or early on the basis of relative SA, the difference between SA and CA. Players who reached skeletal maturity were labeled mature. Results: SA was in advance of CA. Among 14 players >15.0 years, two are skeletally mature with the Fels method ( CA 15.7 and 15.9 years), while 11 are skeletally mature with the TW3 method (CA 15.0-16.1 years). Conclusion: The TW3 and Fels methods yield different SAs in elite youth soccer players. Significantly more 15-year-old boys are classified as skeletally mature with the TW3 method than with the Fels method. These observations have implications for international age group competitions as well as for medico-legal circumstances that require CA verification. SA is not a valid measure of CA and should not be used as such.