C1-ring оsteosynthesis as a functionally preserving operation for unstable atlas fractures

Objective. To analyze the dynamics of pain syndrome, quality of life and functional status of patients with unstable atlas fractures after C1-ring osteosynthesis. Material and Methods. Study design: observational retrospective case series study (n = 15). The intensity of pain syndrome was assessed using the VAS scale before surgery, 3 days, and 3 and 6 months after surgery. The quality of life was assessed using the Neck Disability Index (NDI) before surgery, and 3 and 6 months after surgery. Functional status, as well as cervical spine range of motion (head turn left/right, flexion/extension) was assessed 3 and 6 months after surgery. The integrity of the atlas bone ring and the degree of fusion after fixation were assessed using axial CT scans; and the lateral mass separation was assessed using frontal CT scans. The criterion for transverse ligament injury was a separation of lateral masses of more than 8.1 mm. Results. All patients had C1 fractures type 3B according to Gehweiler, out of them 7 patients (46.7 %) had traumatic injury to the atlas transverse ligament according to Dickman type 1, and 8 patients (53.3 according to Dickman type 2. The average age of patients was 40 years (12; 71), the male/female ratio was 2/1. In 7 patients (46.7 %), the cause of injury was diving, in 6 (40.0 %) it was a traffic accident, and in 2 (13.3 %) – a fall from a standing height. Observation of patients revealed a positive dynamics in the form of statistically significant regression of pain according to VAS before and 6 months after surgery from 6.8 (6.0; 8.0) to 1.0 (1.0; 0.0) points (Z = -3.434; p = 0.001). A positive trend was also noted in the form of a decrease in NDI scores and an improvement in the quality of life after 3 (Z = -3.411; p = 0.001) and 6 months after surgery (Z = -3.410; p = 0.001). The range of motion (turn left/right, flexion/extension) increased statistically significantly by the 6th month after C1-ring osteosynthesis, and its indicators were close to physiological ones. Postoperative CT scans showed positive dynamics in the form of statistically significant regression of the lateral mass separation from 10.4 mm (8.9; 11.4) to 2.2 mm (1.8; 2.6); Z = -3.408; p = 0.001. Complete fusion of the atlas fracture was observed after 12.5 months (8.5; 16.5). Conclusion. Isolated posterior osteosynthesis of the atlas ring for Gehweiler type 3B injury using a repositioning compression maneuver under distraction conditions is physiologically justified. It is a reliable method of stabilization, ensures the restoration of congruence and the entire range of motion in the atlanto-occipital and atlantoaxial joints and stability of the occipital-atlantoaxial complex. This operation contributes to a considerable and long-term reduction in the intensity of pain syndrome and a significant improvement in the quality of life.