Tanner-Whitehouse Skeletal Ages in Male Youth Soccer Players: TW2 or TW3?

Background. The Tanner-Whitehouse radius-ulna-short bone protocol (TW2 RUS SA) is a widely used indicator of maturity status. The scale for converting ratings to an SA has been revised (TW3 RUS SA) which may have implications for studies of youth athletes. Objectives. To compare TW2 and TW3 RUS SAs in an international sample of youth soccer players and to compare distributions of players by maturity status defined by each SA Methods. SA assessments with the TW RUS method were collated for 1831 soccer players 11-17 years from 8 countries. RUS scores were converted to TW2 and TW3 SAs using the appropriate tables. SAs were compared within chronological age (CA) groups. The difference of SA minus CA with each method was used to classify players as late, average or early maturing. Concordance of maturity classifications with TW2 and TW3 SAs was evaluated with Cohen’s Kappa coefficients. Results. For the same RUS score, SAs were systematically and substantially reduced with TW3 compared to TW2; mean differences ranged, on average, from -0.97 to -1.16 years. Kappa coefficients indicated fair concordance of maturity classifications based on TW2 and TW3 SAs. Conclusion. TW3 SAs were systematically lower than corresponding TW2 SAs in youth soccer players. The differences between scales have major implications for the classification of players by maturity status, which is central to many talent development programs.