CORRELATION OF craniovertebral PARAMETERS WITH THE RETROPHARYNGEAL SPACE IN POSTERIOR C1-C2 ARTHRODESIS

ABSTRACT Introduction/Objective: The craniovertebral junction (CVJ) requires a detailed evaluation, as the changes in alignment caused by surgery can affect adjacent structures in a secondary way. Examples of these effects are dyspnea or dysphagia after posterior occipitocervical arthrodesis, due to decreased caliber of the oropharynx. These changes can be identified perioperatively by several radiographic parameters that aim to predict possible postoperative respiratory complications. Such complications appear to be related to the narrowest oropharyngeal airway space (nPAS), and may also occur following atlantoaxial (C1-C2) arthrodesis. This work aims to correlate the variation in CVJ alignment parameters before and after C1-C2 arthrodesis with the variation in nPAS. Methods: Patients who underwent posterior C1-C2 arthrodesis between 2011 and 2019 at the National Institute of Traumatology and Orthopedics (INTO) were included in the study, totaling 26 patients. The parameters evaluated included cervical lordosis, C1-C2 angle, slope of C2, Occipito-C2 angle (O-C2), pharyngeal inlet angle (PIA), pharyngeal tilt angle (PTA), occiput and external acoustic meatus to axis angle (O-EAa), cranial transverse motion against C2 angle (C2TA), axial tilt (AT) and the percentage of change in nPAS (%∆nPAS). Results: A correlation was observed between the change in C1-C2 angle, O-C2, PTA, C2TA and the %∆nPAS. Conclusion: The change in cervical alignment and CVJ parameters is correlated with %∆nPAS and should, therefore, be evaluated before and after atlantoaxial fusion as a means of predicting a possible respiratory complication. Level of Evidence: III; Cross sectional study .