Atlantoaxial Instability in the Course of Rheumatoid Arthritis in Relation to Selected Parameters of Sagittal Balance

Background: Atlantoaxial instability is the most common cervical instability in patients with rheumatoid arthritis (RA). Its course may differ in different patients and may have different degrees of severity and symptoms. Methods: There are a number of studies on systemic factors associated with the development of this instability, but there are few publications in the scientific literature on the influence of biomechanical factors on the development of cervical instability. One of the areas that allows the study of biomechanical factors influencing spine pathologies is the analysis of sagittal balance using radiological parameters. The study of radiological parameters of sagittal balance has contributed to understanding the pathology of selected spine diseases and is currently an indispensable tool in planning surgical treatment. Results: The presented study, conducted on a group of RA patients with cervical instability, was performed to look for a relationship between C1–C2 instability and sagittal balance parameters. Conclusions: Among the examined selected parameters, a statistically relationship between C1–C2 instability and the Cobb angle C1–C7 and OD-HA parameters has been found. This confirms the need for further in-depth research on this areas.