Incidence of complications of the screw osteosynthesis of odontoid process fractures

In this retrospective clinical study the incidence of complications in 58 consecutive, with anterior screw fixation stabilized patients after fractures of the odontoid process is evaluated. In 51 patients the fracture has been defined as type 11 according to Anderson, in 6 patients an oblique type 11 fracture was present and one patient showed a cephalad type III fracture. Preoperatively, in only 19% of the patients (n = 11) no dislocation of the dens occurred. 32 patients were treated with single screw osteosynthesis, in 26 patients two screws were implanted. Significant complications with clinical relevance were registered in 14 patients (24%), in 10 cases (17%) an operative reintervention was required. Intraoperatively, in one patient a rupture of the carotid artery while winding around the motor drill occurred and in another case a complete malplacement of the screw posteriorly to the odontoid process was observed. A clearly excentric positioning of the implant was evaluated in 5 patients with a consecutive high rate of implant migration (n = 3). Two patients died perioperatively not related to the cervical injury. Postoperatively, one patient with a wound infection due to an iatrogenic perforation of the esophagus required reoperation as well as 4 patients with instability because of implant migration. Patients beyond the age of 65 years (n = 3) were significantly overrepresented in that group. In one case, the secondary intervention was caused by a pseudarthrosis of the dens axis. Complications without any relevance to the clinical and functional long term result were fusions in malposition of the odontoid process in 14 patients (24%) and 10 (17%) marginal screw perforations laterally. Differences in the use of one or two screws have not been observed in this study, although the investigations showed a tendency between marginal lateral screw perforations and double screw osteosynthesis and an increasing number of complications in the geriatric cohort.