Modified Atlantoaxial Arthrodesis Technique for Atlantoaxial Instability via Intraarticular Autografting Using Structural Iliac Bone: Technical Nuances and Case Series.

ABSTRACT

OBJECTIVE: The present study described a modified technique of atlantoaxial arthrodesis in patients with atlantoaxial instability (AAI) along with the postoperative clinical and radiological results. METHODS: Five patients underwent this method for their AAI concurrent with C1 arch hypoplasia and/or the development of odontoid pannus causing myelopathy. After thorough exposure of the posterior surface of the C1-2 complex, the bilateral C2 nerve roots were sectioned to allow for easier access to the C1/2 facet joints. To prepare a suitable grafting bed, the C1/2 facet capsule was opened, and then the articular cartilaginous and synovial tissues were thoroughly removed. After being properly fashioned to match the gap between the C1/2 facet joint spaces, the structural bone grafts from the iliac crest were directly inserted into the facet joint spaces. To alleviate cord compression caused by concomitant odontoid pannus and/or hypoplastic C1 arch, C1 laminectomy was necessitated in all cases. Subsequently, posterior screw-rod instrumental fixation was conducted. RESULTS: All 5 patients underwent this procedure successfully. Clinical and radiological follow-up data of all patients indicated favorable relief of clinical symptoms and early rigid C1-2 stability. The sequelae of C2 nerve resection were not remarkable. No other neural or vascular damage associated with this technique was observed. CONCLUSIONS: Modified atlantoaxial arthrodesis via intraarticular autografting using the structural iliac bone combined with posterior instrumentation appears to be an efficient alternative treatment method for AAI patients with concurrent pathologies, even when the C1-2 posterior arches are unavailable for the grafting bed.