Background: The purpose of this study was to determine the incidence of surgery for odontoid fractures and to study surgical mortality, surgical morbidity and long-term outcome in a large, contemporary, consecutive, single institution, surgical series of odontoid fractures.
Methods: This is a retrospective study of all odontoid fractures treated by open surgery at our hospital during 2002–2009. The fractures were classified according to Grauer. Follow-up data, clinical examinations and cervical CTs were collected in 2010.
Results: This study included 97 consecutive patients with a median age of 73.0 years. The incidence of open fixation of odontoid fractures in this population was 0.45 per 100.000, and the incidence increased with age. The fractures were classified as type IIA in 3 patients, type IIB in 63 patients, type IIC in 8 patients and type III in 23 patients. Anterior fixation and posterior fixation were performed in 41 and 56 patients, respectively. Immediate postoperative neurological status was unchanged or improved in 97% of the patients. None of the patients developed postoperative hematoma, wound infection, deep venous thrombosis or pulmonary embolism. Eleven patients underwent resurgery during the follow-up period; five had suboptimal reposition after the first surgery, one had suboptimal position of an anterior odontoid screw, two had rupture of fixation materials, and three developed pseudarthrosis. Overall survival (OS) rates after 1, 12 and 24 months were 96%, 84% and 75%, respectively. Fifty-seven patients were available for follow-up evaluation with a mean time of 37 months. Radiological follow-up showed definite bony fusion in 82% of the patients and uncertain bony fusion in 18% of the patients. Flexion-extension radiographs were obtained in six of the ten patients with uncertain bony fusion; five of these were defined as stable (fibrous union), and one was unstable. Multivariate logistic regression demonstrated increased odds of non-bony fusion in more displaced fractures (OR 1.44, 95% CI (1.04-2.16), p = 0.04) and when using the anterior fusion technique (OR 0.17, 95% CI (0.03-0.75), p = 0.02). There was no significant association between neck pain and fusion method (Mann-Whitney test, p = 0.86). Patients treated with a posterior fusion approach had significantly more neck stiffness than patients who underwent fusion with an anterior odontoid screw (Fisher test, p = 0.04).
Conclusions: The annual incidence of open fixation of odontoid fractures was 0.45 per 100,000 inhabitants, and the incidence increased with age. Median age at time of surgery was 73.0 years, and the surgical mortality was 4%. Increased odds of non-bony fusion were observed in more displaced fractures and after anterior screw fixations. There were no significant differences between patients treated with anterior screw fixation versus posterior wiring with respect to neck pain, but patients fused with a posterior approach reported significantly more neck stiffness.
Key words: Odontoid fracture, trauma, surgery, outcome, fusion rate.