Intraarticular Bone Grafting in Atlantoaxial Facet Joints Via a Posterior Approach: Nonstructural or Structural —A Minimum 24-month Follow-up

Abstract Objective. To investigate the necessity of nonstructural or structural intraarticular bone grafting in atlantoaxial facet joints via a posterior approach and the influence by presence of basilar invagination (BI).Methods. From November 2016 to October 2018, patients who underwent posterior atlantoaxial or occipitocervical arthrodesis surgery at one institute were retrospectively reviewed. Operation records, preoperative and postoperative clinical status and radiological films were analyzed. Results. 33 patients (19 without BI, 14 with BI) underwent posterior facet joint release followed by intraarticular bone grafting were enrolled finally. 24 nonstructural (15 without BI, 9 with BI) and 9 structural (4 without BI, 5 with BI) grafting were performed. The average follow-up was 32.15±6.73 months (24-47 months). Among them, 1 (3.03%) implant failure occurred, 32 (96.97%) achieved satisfactory neurological outcomes, including 28 (84.85%) complete and 4 (12.12%) acceptable reductions with complete fusion within 6 months. For patients without BI, structural and nonstructural grafting showed no significant difference in terms of reduction maintenance (100% vs 73.33%, p = 0.530), while for those with BI, structural grafting significantly increased the postoperative height of the joint space (5.67±1.22 mm vs 3.43±1.78 mm, p = 0.002) and maintained it much better than nonstructural grafting (88.89% vs 20.00%, p = 0.023), contributing notably to BI correction. Conclusion. Intraarticular structural bone grafting in atlantoaxial facet joints has the advantage of maintaining anterior column height in the case of lateral mass collapse or when BI correction is needed, otherwise, nonstructural bone grafting is enough.