Koilonychia of the toenails in children

Two hundred twenty-four children were examined for koilonychia of the toenails. Koilonychia was encountered in 55 out of 171 (32%) kibbutz children compared with 9 out of 53 (17%) of urban children (p less than 0.046). The most likely explanation for the increased prevalence of koilonychia in kibbutz children is habitual minor trauma associated with barefoot walking and frequent water immersion.