Clinical and Radiographic Outcomes of Modified Posterior Atlantoaxial Temporary Fixation with Preservation of Semispinalis Cervicis: A Comparative Study

STUDY DESIGN: Retrospective study. OBJECTIVE: Current studies suggested that the posterior cervical deep muscles should be preserved during the atlantoaxial posterior approach. This study aimed to modify the conventional temporary posterior fixation by preserving the semispinalis cervicis and to evaluate the radiographic and clinical outcomes compared with the conventional technique. METHODS: Applied anatomical and imaging study were assessed prior to the clinical studies. Thirty patients with odontoid fracture were enrolled. 12 patients underwent modified operation with preservation of semispinalis cervicis (Group P-SSC), and 18 patients underwent conventional approach with detachment of the semispinalis cervicis (Group D-SSC) as controls. Clinical and radiological assessments were evaluated postoperatively, including activities of daily living (ADL), axial symptom scoring system (Ass), cervical range of motion (ROM), and the average atrophy rate of muscles. RESULTS: All patients experienced fracture healed within 10 months after temporary fixation. At early follow-up, ADL accompanying extension and flexion were significantly different between the two groups. The Ass scores in the Group P-SSC were constantly higher than that in Group D-SSC. Flexion-Extension ROM in Group P-SSC was significantly larger than that of Group D-SSC. The average atrophy rate at the C3 and C5 level in Group P-SSC was 7.62±3.38% and 7.55±3.89%, repectivcly, while 15.67±5.97% and 8.56±4.76% in Group D-SSC, respectively. Significant differences in the atrophy rate were found between groups at C3 level. CONCLUSIONS: Compared with the conventional technique, the modified surgical technique with preservation of semispinalis cervicis was effective in improving axial symptoms, decreasing the atrophy rate of muscles, and increasing the cervical ROM.