Atlantodentoplasty using the anterior retropharyngeal approach for treating irreducible atlantoaxial dislocation with atlantodental bony obstruction: a retrospective study

Study design: This was a retrospective study.

Purpose: The current study aimed to investigate the clinical efficacy of atlantodentoplasty using the anterior retropharyngeal approach against irreducible atlantoaxial dislocation with atlantodental bony obstruction.

Overview of literature: In cases of atlantoaxial dislocation with atlantodental bony obstruction, owing to the presence of an osteogenic mass between the atlas and odontoid process, reduction is challenging to complete using the posterior approach. Transoral odontoidectomy is technically demanding and is associated with several risks.

Methods: The clinical data of 26 patients diagnosed with irreducible atlantoaxial dislocation complicated by atlantodental bony obstruction were analyzed retrospectively. All patients underwent anterior retropharyngeal atlantodentoplasty, followed by posterior occipitocervical fusion. Details including surgical duration and blood loss volume were recorded. Radiographic data such as the anterior atlantodental interval, O-C2 angle, space available for the cord, clivus-canal angle, and cervical medullary angle, and clinical data including the Japanese Orthopedic Association (JOA) score were assessed. The fusion time of the grafted bone and the development of complications were examined.

Results: In patients undergoing anterior retropharyngeal atlantodentoplasty, the surgical duration and blood loss volume were 120.1±16.4 minutes and 100.6±33.5 mL, respectively. The anterior atlantodental interval decreased significantly after the surgery (p <0.001). The O-C2 angle, space available for the cord, clivus-canal angle, and cervical medullary angle increased significantly after the surgery (p <0.001). The JOA score during the latest follow-up significantly increased compared with that before the surgery (p <0.001). The improvement rate of the JOA score was 80.8%±18.1%. The fusion time of the grafted bone was 3-8 months, with an average of 5.7±1.5 months. In total, 11 patients presented with postoperative dysphagia and three with irritating cough. However, none of them exhibited other major complications.

Conclusions: Anterior retropharyngeal atlantodentoplasty can anatomically reduce the atlantoaxial joint with a satisfactory clinical outcome in patients with irreducible atlantoaxial dislocation with atlantodental bony obstruction.