gms | German Medical Science

Objectives: To evaluate the clinical outcomes for the treatment of basilar invagination (BI) with irreducible atlantoaxial dislocation (irAAD) by posterior approach release and reduction followed by intra-articular interbody fusion cage implantation.

Methods: Between January 2010 and January 2020, clinical data of patients who had BI-irAAD received surgery at our institution were retrospective analyzed. A total of 19 patients were enrolled, including 11 males and 8 females. The age of the cohort was 37.4 ± 13.9 years (range 13 – 69 years). Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) scores were recorded to evaluate the relief of neck pain and the recovery of neurological functions, respectively. The atlantodental interval (ADI), apex distance of odontoid to Chamberlain’s line (DOCL), and cervico-medullary angle (CMA) were measured to evaluate the reduction of AAD and BI. The duration of bony fusion and complications were also recorded and analyzed.

Results: The follow-up period was 54.7 ± 29.4 months (range 25 – 131 months). The duration of surgery was 136.1 ± 29.0 mins (range 95 – 210 mins), and the estimated blood loss was 189.7 ± 85.0 ml (range 100 – 455 ml). For functional scores, the VAS was 6.06 ± 1.21 pre-operation, 2.35 ± 0.76 post-operation, and 1.12 ± 0.90 at the latest follow-up (F = 97.59, P < 0.001). The JOA was 9.26 ± 2.24 pre-operation, 14.05 ± 2.01 post-operation, and 15.16 ± 1.42 at the latest follow-up (F = 41.27, P < 0.001). Regarding the dislocation, the ADI was 9.63 ± 1.93 mm pre-operation, 1.21 ± 1.10 mm post-operation, and 1.26 ± 1.02 mm at the latest follow-up (F = 174.88, P < 0.001). The DOCL was 11.47 ± 3.93 mm pre-operation, 2.53 ± 3.30 mm post-operation, and 2.26 ± 2.73 mm at the latest follow-up (F = 33.97, P < 0.001). The CMA was 114.31 ± 11.00° pre-operation, 144.16 ± 9.33° post-operation, and 143.42 ± 9.12° at the latest follow-up (F = 41.05, P < 0.001). Bony fusion was achieved in all patients, the fusion time was 10.3 ± 2.7 months (range 5 - 15 months). Of these patients, one developed wound infection and one developed cerebrospinal fluid leakage. The two patients were cured through corresponding management. No patient developed implant failure or re-dislocation.

Conclusion: Posterior approach release and reduction followed by intra-articular interbody fusion cage implantation is a safe and efficient surgical strategy for the treatment of BI-irAAD.