Atlantoaxial Stabilization by Posterior C1 and C2 Screw-Rod Fixation for Various Pathologies: Case Series and Comprehensive Review of Literature

The retropharyngeal reduction plate for atlantoaxial dislocation: a finite element analysis

Objective: To investigate the biomechanical properties of the retropharyngeal reduction plate by comparing the traditional posterior pedicle screw-rod fixation by finite element analysis. Methods: Two three-dimensional finite element digital models of the retropharyngeal reduction plate and posterior pedicle screw-rod fixation were constructed and validated based on the DICOM (Digital Imaging and Communications in Medicine) data from C1 to C4. The biomechanical finite element analysis values of two internal fixations were measured and calculated under different conditions, including flexion, extension, bending, and rotation. Results: In addition to the backward extension, there was no significant difference in the maximum von Mises stress between the retropharyngeal reduction plate and posterior pedicle screw fixation under other movement conditions. The retropharyngeal reduction plate has a more uniform distribution under different conditions, such as flexion, extension, bending, and rotation. The stress tolerance of the two internal fixations was basically consistent in flexion, extension, left bending, and right bending. Conclusion: The retropharyngeal reduction plate has a relatively good biomechanical stability without obvious stress concentration under different movement conditions. It shows potential as a fixation option for the treatment of atlantoaxial dislocation.

C1-C2 Rotatory Subluxation in Adults “A Narrative Review”

The atlantoaxial joint C2 (axis) with the anterior arch of C1 (atlas) allows 50% of cervical lateral rotation. It is responsible for precise and important movements that allow us to perform precise actions, both in normal and working life. Due to low incidence in adults, this condition often goes undiagnosed, or the diagnosis is delayed and the outcome is worse. An early diagnosis and treatment are essential to ensure satisfactory neurological and functional outcomes. The aim of this review is to analyze C1-C2 rotatory subluxation in adults, given its rarity. The time between injury and reduction is key, as it is directly related to prognosis and the severity of the treatment options. Due to low incidence in adults, this condition often goes undiagnosed, or the diagnosis is delayed as a lot of cases are not related to a clear trauma, with a poor prognosis just because of the late diagnosis and the outcome is worse. The correct approach and treatment of atlantoaxial dislocation requires a careful study of the radiological findings to decide the direction and plane of the dislocation, and the search for associated skeletal anomalies.