Clinical efficacy of posterior approach release and reduction of lateral mass joint followed by bone grafting and occipital-cervical internal fixation for basilar invagination with irreducible atlantoaxial dislocation

English Keywords:Basilar invagination  Irreducible atlantoaxial dislocation  Interbody fusion cage  Lateral mass joint bone graft and fusion

English Abstract:

  【Abstract】 Objectives: To evaluate the clinical outcomes for the treatment of basilar invagination(BI) with irreducible atlantoaxial dislocation(irAAD) through posterior approach release and reduction of lateral mass joint followed by bone grafting and occipital-cervical internal fixation. Methods: The clinical data of patients of BI-irAAD undergone posterior approach release and reduction of lateral mass joint followed by bone grafting and occipital-cervical internal fixation at our institution between January 2010 and January 2020 were retrospectively analyzed. A total of 19 patients were enrolled, including 11 males and 8 females. The average age of the patients was 37.4±13.9 years(range 13-69 years), and the follow-up period was 54.7±29.4 months(25-131 months). Visual analogue scale(VAS) and Japanese Orthopaedic Association(JOA) scores before operation, at postoperative 1 week, six month and final follow-up were recorded to evaluate the relief of neck pain and the recovery of neurological functions, respectively. The atlantodental interval(ADI), distance of the top of odontoid to Chamberlain′s line(DOCL), and cervico-medullary angle(CMA) before operation, at postoperative 1 week and final follow-up were measured on cervical midsagittal CT and MRI. The bony fusion condition was evaluated on CT and complications were also recorded. Results: The operative time was 136.1±29.0min(range 95-210min) and blood loss was 189.7±85.0mL(range 100-455mL). For functional scores, the VAS was 6.06±1.21 points preoperatively, 2.35±0.76 points at one week postoperatively, 1.24±0.81 points at six months of follow-up, and 1.12±0.90 points at the final follow-up. The JOA was 9.26±2.24 points preoperatively, 14.05±2.01 points at one week postoperatively, 15.05±1.57 points at six months of follow-up, and 15.16±1.42 points at the final follow-up. The VAS and JOA at one week postoperatively, six months of follow-up, and final follow-up significantly improved than those before operation(P<0.05). Regarding dislocation, the ADI was 9.63±1.93mm preoperatively, 1.21±1.10 mm at one week postoperatively, 1.16±1.09mm at six months of follow-up, and 1.26±1.02mm at the final follow-up. The DOCL was 11.47±3.93mm preoperatively, 2.53±3.30mm at one week postoperatively, 2.32±3.20mm at six months of follow-up, and 2.26±2.73 mm at the final follow-up. The CMA was 114.31°±11.00° preoperatively, 144.16°±9.33° at one week postoperatively, 145.31°±8.83° at six months of follow-up, and 143.42°±9.12° at the final follow-up(P<0.05). The ADI, DOCL and CMA at one week postoperatively, six months of follow-up, and final follow-up significantly improved than those before operation(P<0.05). Bony fusion was achieved in all patients, the fusion duration 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. Conclusions: Posterior approach release and reduction of lateral mass joint followed by bone grafting and occipital-cervical internal fixation is a safe and efficient surgical strategy for the treatment of BI-irrAAD.