Odontoid fractures constitute 15–20% of all cervical spine fractures and are formed by a combination of flexion, axial loading or extension, and rotational forces. Type II fractures constitute 60% of odontoid fractures [9]. Odontoid fractures seen in young age are frequently observed in males, but there is no gender difference in the prevalence of odontoid fractures seen in old age [9]. The most common cause of odontoid fracture is trauma [10]. All of our cases presented with a history of a traffic accident or fall from height.
Post-traumatic neck pain in odontoid fractures can often be the only complaint. Non-displaced fractures can be overlooked in direct radiography, axial CT and magnetic resonance images. the best imaging modality is CT reconstructions [10]. In the present study, all patients had preoperative CT with 3-dimensional reconstruction.
It is reported that there are many factors affecting the percentage of fusion. Dunn and Seljeskog stated that posterior dislocation, being 64 years and over, and having severe neurological deficits were negative factors in the achievement of the union [11]. In a series of 45 patients, Apuzzo et al. found the rate of nonunion as 33% in patients over 40 years of age and in patients having dislocation over 4 mm. [12]. The degree of dislocation of dens is the most frequently affecting factor in the percentage of the union in external immobilization. In their series of 107 cases, Hadley et al. reported nonunion rates as 67, and 9% in dislocations of more and less than 6 mm, respectively [13]. In the present study, ten patients had odontoid displacement more than 5 mm (mean 6.2 mm), and 12 patients had posterior dens displacement.
In the present study, 96% fusion rates were achieved by posterior C1-C2 fixation. In literature, nearly 90–100% fusion rates were achieved with lower complication and mortality rates [14, 15]. Complication rates were similar to literature. During the application of C1 and C2 screwing techniques, many complications involving the vascular and neural anatomical structures contained in this region should be avoided. Therefore, many researchers strive to develop different techniques [16]. Abumi et al. reported that the C2 pars screwing technique was very safe and screw malposition decreased to 7% in proportion to developing technology and experience [17]. In our study, nonunion was observed in only one (3.1%) patient, but revision surgery was not needed due to the absence of any neurological deficit. In the initial evaluation and follow-up of patients with cervical trauma, various authors evaluated the clinical and neurological recovery with different parameters such as ASIA, Frankel, JOA score or subjective satisfaction [18, 19]. Song et al. reported a 78.3% improvement in the JAO score with the surgical treatment in patients with unstable cervical injury [20]. We used the JOA scores in our study.
In their study, Jing et al. detected their complication rate as 6.67% (2 patients). In one patient, while inserting a screw into the C1 lateral mass, intraoperative vertebral artery damage occurred in one patient, and screw loosening happened in the follow-up of another patient [21]. In their study, Zheng et al.reported venous plexus injury in 6 patients (7%), C2 root injury in 4 patients (4.7%), urinary tract infection in 1 patient and wound infection in 1 patient [22]. Kizmazoglu et al. reported peroperative dura mater damage in 2 (18.2%), postoperative wound discharge in 4 patients (36.4%), while one patient died due to postoperative cardiac arrest [23]. In our study, surgical wound infection, hematoma, pulmonary embolism, and cerebrovascular events developed in individual patients and treatment was provided for all patients. One patient developed nosocomial pneumonia, and the patient died at postoperative sixth week.
Although the VAS is an incomplete representation of the pain experience and cannot fully reflect the multidimensional aspects of pain, it remains the most widely used metrics of pain after surgery. However, VAS would not always reflect the sense of pain. That may be the reason of which three patients had worse VAS scores at final follow up compared the pre-surgery VAS score.
The main limitations of the present study were the retrospective design and the relatively small size of our series. Also, some details of history and factors that may influence the outcome may not be completely documented. Finally, surgeries were performed by different surgeons. Due to these restrictions, associations should be interpreted with caution.