stylistic:style_transfer, structural:expansion
Development

The elbow undergoes dynamic development of ossification centers through infancy and adolescence, with the order of both the appearance and fusion of the apophyseal growth centers being crucial in assessment of the pediatric elbow on radiograph, in order to distinguish a traumatic fracture or apophyseal separation from normal development. The order of appearance can be understood by the mnemonic CRITOE, referring to the capitellum, radial head, internal epicondyle, trochlea, olecranon, and external epicondyle at ages 1, 3, 5, 7, 9 and 11 years. These apophyseal centers then fuse during adolescence, with the internal epicondyle and olecranon fusing last. The ages of fusion are more variable than ossification, but normally occur at 13, 15, 17, 13, 16 and 13 years, respectively. In addition, the presence of a joint effusion can be inferenced by the presence of the fat pad sign, a structure that is normally physiologically present, but pathologic when elevated by fluid, and always pathologic when posterior.