[Short-term effectiveness of axis laminar screws for reducible atlantoaxial dislocation].

Objective: To investigate reliability and short-term effectiveness of axis laminar screws for reducible atlantoaxial dislocation (RAAD).

Methods: A clinical data of 41 patients with RAAD who were admitted between February 2013 and February 2018 and met the inclusion criteria was retrospectively analyzed. The atlases in all patients were fixated by lateral mass screws, and the axes were fixed by laminar screws in 13 cases (LS group) and by pedicle screws in 28 cases (PS group). There was no significant difference in gender, age, and preoperative Japanese Orthopedic Association (JOA) score between the two groups ( >0.05). The effectiveness was estimated by post-operative JOA score; and the accuracy of the axis screw, atlantoaxial bone graft fusion, and the fixation stability were examined by X-ray film and CT.

Results: All incisions healed by first intention. All patients were followed up 12-17 months (mean, 13.8 months) in LS group and 12-20 months (mean 14.1 months) in PS group, and the difference in follow-up time was not significant ( =-0.704, =0.482). At last follow-up, JOA scores were 13.9±1.6 in LS group and 14.3±1.8 in PS group, which significantly improved when compared with the pre-operative scores in the two groups ( =-9.033, =0.000; =-15.835, =0.000); while no significant difference was found between the two groups ( =-0.630, =0.532). Twenty-five screws of 26 screws in LS group and 54 screws of 56 screws in PS group were implanted accurately, with no significant difference in the accuracy of the axis screw between the two groups ( =-0.061, =0.951). All patients obtained atlantoaxial bone graft fusion, except 1 case in PS group. There was no significant difference in the atlantoaxial bone graft fusion between the two groups ( =-0.681, =0.496).

Conclusion: For RAAD, Axis laminar screws can maintain the atlantoaxial primary stability and had a good short-term effectiveness. So, it could be an alternative and reliable technique for axis screw.