Atlantoaxial Instability: Clinical, Radiological, and Therapeutic Aspects. Literature Review

Background: Atlantoaxial instability (AAI) is characterized by abnormal motion between the atlas (C1) and axis (C2), potentially leading to spinal cord compression and significant neurological deficits. Its etiology is multifactorial and includes congenital anomalies, traumatic injuries, inflammatory diseases, and degenerative conditions. Early diagnosis and appropriate treatment are essential to prevent neurological complications [1-4].

Objective: To perform a narrative review of the literature on atlantoaxial instability, focusing on its anatomy, etiology, diagnostic methods, and current surgical management.

Methods: A literature search was conducted in PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar for studies published between 1937 and 2025. Original studies, case series, reviews, and relevant technical reports addressing atlantoaxial instability were included. A total of 47 articles were selected for analysis.

Results: Current evidence indicates that the diagnosis of AAI relies on the correlation between clinical findings and imaging studies such as dynamic radiographs, computed tomography, and magnetic resonance imaging [5-7]. Radiological parameters including the anterior atlantodental interval (AADI) and posterior atlantodental interval (PADI) are essential for evaluating atlantoaxial stability [37]. Regarding treatment, modern posterior C1-C2 fixation techniques using screw-rod constructs have demonstrated fusion rates exceeding 90% and superior biomechanical stability compared with traditional wiring techniques [10-12]. Recent technological advances, including intraoperative navigation, 3D-printed surgical guides, and augmented reality, have further improved the accuracy and safety of atlantoaxial instrumentation [43-45].

Conclusions: Atlantoaxial instability is a complex condition requiring careful clinical and radiological assessment. Posterior C1-C2 fixation techniques currently represent the standard surgical approach, while emerging technologies continue to enhance the precision and safety of surgical management.