Comparison of Outcomes Between C1-C2 Screw-Hook Fixation and C1-C2 Screw-Rod Fixation for Treating Reducible Atlantoaxial Dislocation

Study Design. Retrospective comparative study. Objective. To compare the outcomes of C1-C2 transarticular screw with C1 laminar hook (TAS+C1H) fixation and C1 transarch lateral mass screw with C2 pedicle screw (C1TLMS+C2PS) fixation in the treatment of reducible atlantoaxial dislocation (AAD). Summary of Background Data. TAS+C1H is comparable to TAS with posterior wiring techniques and superior to C1 lateral mass screw combined with C2 pedicle screw (C1LMS+C2PS) in biomechanics. There were, however, few studies analyzing the differences in outcomes between TAS+C1H technique and modified C1LMS+C2PS technique (C1TLMS+C2PS) for treating AAD. Methods. Data of 30 patients with reducible AAD treated by TAS +C1H fixation and another 30 cases treated by C1TLMS+C2PS fixation were retrospectively analyzed. Bone fusion time was recorded. The outcomes evaluated by American Spinal Injury Association impairment scale, visual analog scale score for neck pain, neck stiffness (none/mild/severe), patient satisfaction, and Neck Disability Index (NDI) were compared between two groups. Results. There were no complications related to the surgical approach and instrumentation in either group. At the final follow-up, bone graft fusion rates were 100% in both the TAS+C1H fixation group and the C1TLMS+C2PS fixation group (P>0.05). The neurological status evaluated by American Spinal Injury Association impairment scale were greatly improved in both screw-hook group (P<0.001) and screw-rod group (P<0.001), but with no significant differences between groups (P>0.05). There were no significant differences between two groups in visual analog scale score for neck pain, neck stiffness, patient satisfaction, or Neck Disability Index (all P> 0.05). Conclusion. C1TLMS+C2PS fixation was comparable to TAS+C1H fixation in fusion rate and functional outcomes for treating reducible AAD. To reduce the risk of vertebral artery injury, computed tomography scan, and reconstruction should be done to analyze vertebral artery course and C1-C2 anatomic structures before operation.