Subaxial cervical spine ligamentous instability anterior versus posterior fixation: prospective nonrandomized study

Background The goals of cervical internal fixation are to provide immediate stability to control an unstable segment and to improve bony union. Early cervical fixation methods preferred a posterior approach and consisted of simple wire and cancellous bone graft. Later, anterior, and posterior fixation became recent additions to surgeon's armamentarium. Objectives Comparing between anterior and posterior fixation in cervical subaxial ligamentous subluxation regarding the applicability, safety, and clinical efficacy in achieving stability and enhancing bony union. Also cost-related variables are studied. Methods This prospective clinical and radiographic analysis was performed on 40 patients with cervical subaxial ligamentous subluxation. Half of these patients were treated with anterior cervical fixation and interlocking screws with inter-body cage fusion. The other half was treated by posterior fixation with lateral mass fixation and inter-facet bone fusion. Results There were 27 male and 13 female patients with mean age 37.4 years. The level of cervical dislocation was C4-5 in four, C5-6 in 14, C6-7 in 20 and more than one level in two patients. Closed reduction was achieved in 33 patients while open reduction through the posterior approach was done in four cases and through anterior approach in other three cases. Statistically significant difference between the two groups was found for estimated blood loss and operating room time with better results in the anterior group. There were no perioperative deaths in both groups. Regarding surgery-related complications, there was injury to a cervical root during posterior fixation in two cases. There was no statistical difference between the two groups regarding the length of the hospital stay. The mean hospital stay was 7 days. Positioning of the plate and screws in all cases was satisfactory. All patients were followed up for at least 6 months. Mean follow-up period was 13 months. Vertebral body alignment (radiological stability) was achieved in all cases with anterior fixation while one case with posterior fixation showed delayed subluxation. Solid bony cage fusion was found in 85% with anterior fixation and solid bony fusion in 70% with lateral mass fixation. Conclusions Although some of the literature have indicated that posterior fixation in ligamentous cervical subaxial injury is more solid than anterior fixation, yet most of these studies were done on cadaver subjects so eliminating any bony fusion, long-term stability, and hardware failure. This study proved that anterior cervical fixation is not only safer and simple procedure than posterior fixation, but also it restores the cervical stability better than the posterior fixation.