[Atypical dislocated dens fracture type II with rotational atlantoaxial luxation after a riding accident].

We present a rare case of a combined dislocated odontoid dens fracture type II (Anderson/D'Alonzo) and rotational atlantoaxial luxation in a 15-year-old girl who was involved in a riding accident.She fell off her horse after it had stopped suddenly, losing consciousness for a few minutes. At presentation in the hospital, she had no complaints other than limited, painful neck movement. Radiologically, a posterior dislocation of an odontoid type II fracture (Anderson/D'Alonzo) was found. Computed tomography reconstruction demonstrated a rotational, hooklike fixed luxation of the left atlantoaxial facet joint. Manual repositioning after application of a cervical collar failed. Therefore, operative treatment was indicated for this highly unstable fracture. Posterior transarticular atlantoaxial screw fixation according to Magerl was performed; an iliac corticocancellous bone graft was harvested and shaped to conform to the posterior processes of C1 and C2. Additionally a hook-claw atlas fixation of C1 was done.To our knowledge, this is the first case of adolescent atlantoaxial cervical spine trauma in combination with an odontoid fracture and fixed rotational luxation reported in literature.