Clinical effect of posterior hybrid cervical fixations in the treatment of atlantoaxial instability or dislocation

English Keywords:Atlantoaxial instability  Atlantoaxial dislocation  Hybrid fixations  C2 laminar screw  Pedicle screw  Spinous process screw

English Abstract:

  【Abstract】 Objectives: To evaluate the clinical result of posterior hybrid cervical fixations for atlantoaxial instability or dislocation. Methods: Fifty eight cases were retrospectively studied, including twenty four male and thirty four female, with the mean age of 47.8±14.7. Thirty three cases were diagnosed as atlantoaxial instability, while twenty five cases as atlantoaxial dislocation. Among the fifty eight cases, thirty two had cervical myelopathy and their JOA scores ranged from 8 to 16(mean 13.2±1.8). The hybrid fixation techniques included C1-C2 pedicle screw, C1-2 transarticular screw, C2 laminar screw, cervical lateral mass screw and spinious process screw. Forty five cases underwent posterior cervical fixation using two hybriid techniques, nine cases using three techniques, and four using four techniques. The reasons for hybrid fixations included: vertebral artery high-riding in C2, C2 vertebral body dysplasia, pedicle hypogenesis in Klippel-Feil syndrome, severe osteoporosis of C2 pedicle and iatrogenic C2 pedicle fracture. Atlantoaxial fixation was performed in twenty two cases, while occiput-cervical fixation used in thirty six cases. The fusion rate and complications were observed, and the spinal cord function before and after the operation was compared. Results: No spinal cord injury or vertebral artery injury occurred. The mean follow-up was 36.8±10.5 months. Fifty seven cases(98.3%) achieved solid osseous fusion without hardware failure. All thirty two cases with preoperative myelopathy had postoperative improvement and their JOA scores ranged from 11 to 17, with the mean of 15.2±1.5. Six cases suffered with complications, including delayed wound healing, CSF leakage, and fixation loosening followed by revision. Conclusions: For atlantoaxial instability or dislocation concomitant with osseous and vascular deformity, or technical failure in typical procedure , posterior hybrid cervical fixations can safely achieve good clinical results.