There are several diagnostic pitfalls in the interpretation of roentgenograms of the cervical spine in children with suspected neck injuries. Incomplete ossification, epiphyscal variations, unique bone architecture, and relative hypermobility may all contribute to possible diagnostic errors. In this study of 160 normal children's cervical spines, the following suspect normal variations were observed:

1. Variations due to displacement of vertebrae that may resemble subluxation: Marked anterior displacement of the second on the third cervical vertebra, resembling a true subluxation, was observed in 19 per cent of the children studied who were one to seven year old. A similar finding was present less frequently between the third and fourth cervical vertebrae. Overriding of the atlas on the odontoid process, seen on lateral roentgenograms made with the neck in extension, and apparrent wedening of the space between these two structures, visible on flexion views, occurred in 20 per cent of the normal children between one and seven years of age. Both were suggestive of ligamentous injury.

2. Variations of curvature of cervical spine that may resemble spasm and ligamentous injury: Absence of uniform angulation between adjacent vertebrae, absence of the normal lordotic curve in neutral position, and absence of a flexion curvature of the spine between the second and the seventh cervical vertebrae, seen on lateral roentgenograms made with the cervical spine in flexion, were seen at all ages between one and sixteen years, the incidence of each variation ranging between 14 and 16 per cent.

3. Variations related to skeletal growth centers resembling fractures: The presence of the basilar odontoid cartilaginous plate frequently persists in vestigial form until the age of five years or longer and may resemble an undisplaced fracture. The apical odontoid epiphysis is rarely seen on lateral roentgenograms, but should not be mistaken for a fracture. A secondary ossification center of a cervical spinous process was seen only once in this study; there was no resemblance to an avulsion fracture. A center of ossification in the first thoracic spinous process, however, did have some resemblance to a fracture. This variation would not appear to be a pitfall in the diagnosis of neck injury in children and adolescents.

Physicians responsible for the care of children with neck injuries should be conversant with the normal roentgenographic variations.