Atlantoaxial Rotatory Fixation: Part 1—Biomechanics OF Normal Rotation at the Atlantoaxial Joint in Children

C1 and C2 in children move in a predictable manner during axial head rotation, with a high degree of concordance among subjects and a relatively narrow variance from the mean. The composite motion curve can thus be used as a touchstone against which may be judged all manners of pathological interlock or "stickiness" between C1 and C2 in rotation that could be defined as AARF.