Pathomechanism of atlantoaxial rotatory fixation in children.

The pathomechanism of atlantoaxial rotatory fixation (AARF) was studied using roentgenography and computerized tomography in affected children as well as cadaver studies of upper cervical spine anatomy. The increased incidence of AARF in children may be related to certain anatomical differences between children and adults. The dens-facet angle of the axis was steeper in children than in adults. Meniscus-like synovial folds were found in the C0/1 and C1/2 facet joints of the spines of children but not in those of adults.