Skeletal maturity of the hand and wrist of healthy Argentinian children aged 4-12 years, assessed by the TWII method.

One previously trained observer assessed skeletal maturity in a representative sample of 388 and 387 healthy girls and boys respectively from La Plata city, a predominantly university and administrative urban centre in Argentina. The staging system used was TWII and the scores were calculated from three sources: British, Spanish and Italian standards. Our sample showed a marked advancement in bone age with regard to chronological age when using British standards and, to a lesser extent, when applying the Spanish standards. Local mean bone ages were very similar to chronological ages when the Italian scores were used. Second-degree polynomials were adjusted to log10 scores for boys and girls, in order to obtain local values for bone age (BA) transformations. The same staging system should be used in clinical work in Argentina, with the corresponding changes in BA transformatons. A marked advancement of carpal BAs with regard to RUS BAs was found, from age 5 onwards, in both sexes. Mean differences and SD of RUS-minus-carpal BA were 1.28, SD 1.08 and 1.18, SD 1.09 years for girls and boys respectively. These differences have not been described before, and require further investigation.