[Osseus age of the black children of Benin. A population study of 600 children aged from 9 to 18 years and living in Cotonou].

Purpose: The purpose of this work is to study the skeleton maturation in the black population of Benin by means of Tanner Whitehouse method (TW2) in comparison with the populations of the developed countries.

Material And Methods: The study was transversal and analytic. It included 297 boys and 303 girls aged from 9 to 18 years. This was conducted from October 2002 to May 2003 in Cotonou City, the economic capital of Benin. The corrected minimum size of the sample was 384 x 1.19. The sampling technique was chancy, multiphasic, stratified and in clusters. Every one of the 13 districts of Cotonou was considered as a stratum. The interpreter of the anteroposterior radiograph of the left wrist and hand was selected after an intra and extra observer test. The data treatment and analysis were performed by the logiciels Epi info and SPSS. The statistical tests used were Khi 2 test and Kappa index.

Results: The sample was mainly composed of pupils: 84.16% among the boys, 77.23% among the girls. 91.01% of the parents of the children had a middle standard of living. The skeleton maturation score increased with age in all TW2 methods. With the TW2 20 bone and RUS methods, the mature score was reached at percentile 50 among the boys at 18.5 years and among the girls at 17 years. It was precociously reached at percentile 97 respectively at 14 and 14.3 years among the boys and 12.7 years among the girls. With the Carpal bone method, the age of mature score at percentile 50 was 18.2years among the boys and 17.2 years among the girls. The early maturation was obtained at percentile 97 among the boys and the girls respectively at 13.2 and 12.5 years.

Discussion: The skeleton maturation score of the girls in Benin is I to 1.5 years higher than the one of the boys. With the TW2 bone and the RUS methods, the maturation shows a delay of 0.5 to 2.5 years at the percentile 50 and of 1.5 to 2 years at the percentile 97 in relation to the Belgian, British, Chinese, Korean, Japanese, and North American standards. These delays seem to be mainly due to the less favourable socioeconomic conditions in Benin. In the other hand, the more considerable delay of 1 to 4 years with the Carpal bone method remains to be elucidated.

Conclusion: The osseous age stemming from this work is representative of the middle social stratums of the city backgrounds. It would gain to be completed by a similar work concerning the country backgrounds of Benin.