Comparison of the efficacy of anterior combined with posterior approach and posterior- only approach in the treatment of basilar invagination with irreducible atlantoaxial dislocation: minimum 5-year follow-up outcomes

Abstract

Abstract Background: To compare the clinical efficacy of anterior combined with posterior (A-P) approach and posterior-only (P-O) approach release, reduction, and internal fixation in the treatment of basilar invagination (BI) with irreducible atlantoaxial dislocation (AAD). Methods: The clinical records of 49 patients diagnosed with BI with irreducible AAD from July 2000 to June 2017 were analyzed retrospectively. The patients were divided into the A-P group (n = 24) and P-O group (n = 25) according to the operation modes. The primary outcome measures included Chamberlain line (CL), Wackenheim line (WL), McRae line (ML), atlanto-dens interval (ADI), cervicomedullary angle (CMA), clivus-canal angle (CCA), Japanese Orthopaedic Association (JOA) score, and Ranawat grade. Results: The follow-up periods were 68.7 ± 11.2 months in the A-P group and 64.4 ± 13.2 months in the P-O group. The JOA score of the A-P group was 8.25 ± 2.74 before operation and 14.96 ± 1.09 at the last follow-up. The improvement rate was 77.32 ± 11.31%. The JOA score of the P-O group was 8.10 ± 2.48 before operation and 14.69 ± 0.60 at the last follow-up. The improvement rate was 74.32 ± 10.42%. The preoperative CL, WL, ML, ADI, CMA, and CCA of the A-P group were 13.14 ± 5.72 mm, 6.91 ± 3.52 mm, 7.12 ± 4.51 mm, 9.78 ± 2.10 mm, 110.79°± 13.2°, 95.28° ± 18.1°. At the last follow-up, the CL, WL, ML, ADI, CMA, and CCA were 1.69 ± 2.51 mm, -2.71 ± 2.19 mm, -1.50 ± 2.41 mm, 1.13 ± 1.52 mm, 149.16° ± 12.5°, 141.38° ± 13.6° with significant difference compared with the preoperative results. The preoperative CL, WL, ML, ADI, CMA, and CCA of the P-O group were 12.50 ± 5.09 mm, 6.54 ± 3.12 mm, 6.88 ± 4.28 mm, 9.81 ± 1.89 mm, 115.29° ± 12.3°, 97.21° ± 16.6°. At the last follow-up, the CL, WL, ML, ADI, CMA, and CCA were 2.04 ± 3.61 mm, -3.12 ±1.81 mm, -1.72 ± 2.79 mm, 1.15 ± 1.20 mm, 146.69 °± 11.2 °, 137.49° ± 10.3°, which were statistically significant compared with the preoperative results. The bone graft fusion time was 9.1 ± 5.0 months in the A-P group and 9.4 ± 4.8 months in the P-O group. A total of 8 patients presented postoperative complications, including 6 patients in the A-P group (25.0%) and 2 patients in the P-O group (8.0%). The incidence of postoperative complications in the P-O was significantly lower than that in the A-P group. Conclusion: The clinical efficacy of the P-O approach release, reduction, and internal fixation in the treatment of BI with irreducible AAD is basically the same as that of the A-P approach. However, the incidence of complications of the P-O approach is significantly lower than that of the A-P approach.