Anterior displacement of C2 in children: physiologic or pathologic.

Differentiating pseudo-dislocation of the cervical spine from true fracture-dislocation of C2 on C3 is often difficult in children. Normal anterior position of C2 on C3 secondary to normal mobility of this area may be so pronounced that it seems true dislocation is present. A helpful line is presented to aid in the solution of this problem and the anatomy of normal and abnormal (fracture-dislocation) motion at the C2-C3 level will be discussed.