Posterior Reduction And Occipital-cervical Fusion For The Treatment Of Basilar Invagination And Fixed Atlantoaxial Dislocation

Objective: To discuss the reductive method and suigical effect of direct posterior occipital-cervical fusion for the treatment of basilar invagination and fixed atlantoaxial dislocation.Methods: From June 2010 to June 2014, 16 patients with basilar invagination and fixed atlantoaxial dislocation were treated in our department, including 9 males and 7 females, aged 26 to 64 years(mean, 43.4 years). All patients with basilar invagination and fixed atlantoaxial dislocation were associated with anomalies including atlantooccipital assimilation in 16 cases, Klipple-Feil syndrome in 5 cases, Chiari malformation in 4 cases, and syringomyelia in 4 cases. All patients had different degrees of neurological impairment. The atlantoaxial dislocation of all patients did not improve after 2~4 weeks of skull traction. All patients were operated by posterior reduction and occipital-cervical fusion with intraoperative neuro-physiological monitoring. The methods of reduction were pushing the spinous process of C2 forward, moving skull back and distracting occipital-cervical distance by distracting instruments based on nail-stick system and the principle of lever. Occipital-cervical fusion was performed after satisfactory distraction reduction. The JOA score was used to evaluate the improvement of spinal cord function after surgery. Preoperative imaging parameters and postoperative imaging parameters were measured. The extent of horizontal and vertical reduction was calculated.Results: All patients underwent surgery successfully. The operation time was 90~210min(mean, 139.7min), and the blood loss was 80~270ml(mean, 156.6ml). There were no abnormal phenomenon of SEP?MEP and EMG under intraoperative neuro-physiological monitoring. 2 patients suffered from poor healing of incision after operation and were cured by debridement. The followed-up time was 9months to 25 months(mean, 16.5 months). The mean JOA scores of preoperation and last followed-up after operation were 8.8±1.4 score and 14.9±1.6 score. The improvement ratio was 76.4%, then the curative effects were showed: excellent in 9 cases, good in 6 cases, common in 1 case and no poor cases. The rate of excellent and good of the clinical result was 93.8%. Compared to preoperative imaging parameters, postoperative imaging parameters were improved obviously(P<0.01). Compared with the preoperative parameters, complete vertical reduction was achieved in 13 patients(81.3%), and complete horizontal reduction was achieved in 14 patients(87.5%). The rest patients are all received greater than 50% vertical and horizontal reduction. Bone graft fusion of all postoperative patients were achieved. Compared to postoperative imaging parameters, the last followed-up imaging parameters had no loss.Conclusion: Pushing the spinous process of C2 forward, moving skull back and distracting occipital-cervical distance by distracting instruments based on nail-stick system could achieve satisfactory reduction and occipital-cervical fusion in the posterior.