gms | German Medical Science

Objective: Odontoid fractures (Anderson/Alonso °2) may be secondary complicated by dislocation after treatment with an anterior lag screw. Then a posterior C1C2 fusion may be indicated. There exist different techniques for C2 screw insertion: pedicle, pars, lamina or transarticular C1C2 screws have been described. The choice of the technique depends on different factors such as: bone density, -anatomy, vertebral artery course and biomechanical factors.

Method: We present two exemplary cases of odontoid fractures, initially treated with lag screws and secondarily complicated by dislocation. The patients received dorsal fusion C1C2, one with C2-pedicle and the other with C2- lamina screws.

Results: A male patient (75 yo) with dens fracture (Anderson/Alonso °2) was treated with a lag screw. Because stability was judged insufficient a second screw was inserted. After some weeks a new trauma occurred resulting in significant dislocation. The patient was treated with C1C2-fusion with pedicle screws in C2. A female patient (76 yo) had the same pathology with a secondary dislocation because of osteoporosis. Because of small pedicles and an abnormal vertebral artery course, C2-lamina screws were used in this instance. In both patients the further clinical and radiological evolution was good.

Conclusions: It is necessary to possess rescue techniques to stabilize safely and efficiently a secondary dislocated dens fracture. The bilateral pedicular C2 screw placement achieves a very high stability. In case of small C2 pedicles or abnormal vertebral artery course an intralaminar C2 screw placement allows a safe and efficient fusion with lower risk of vascular injury. In our view both techniques represent the best compromise of stability and surgical safety as compared to other techniques.