Relationship between Cervical Instability in the Course of Rheumatoid Arthritis and Pelvic Parameters of Sagittal Balance

Background: The aim of the study is to search for a relationship between cervical instability in the course of rheumatoid arthritis (RA) and pelvic parameters of sagittal balance and lumbar lordosis (LL). Methods: The study included 47 patients with rheumatoid arthritis with instability of the cervical segment, who were referred for a consultation to assess indications for surgical treatment. The patients underwent a radiological functional examination of the cervical region and postural examination of the entire spine. The basic parameters of the lumbar section and pelvis of these patients were compared with the population values. Then, using statistical methods, the correlation between radiological parameters of various types of instability and lumbar lordosis (LL), pelvic parameters (PI, SS, PT), as well as the patient's age and duration of the disease was assessed. Results: A statistical correlation was found between the instability in the cervical spine C2-C3 level and the value of the PT and PI angles. A statistically significant correlation was discovered between C1-C2 instability and younger patient age. There was no significant difference in the values of the pelvic parameters and lumbar lordosis in patients with rheumatoid arthritis compared to the population values. Conclusions: Preliminary results suggest that there is a relationship between selected pelvic parameters and the development of instability in patients with rheumatoid arthritis. This may be important in planning treatment and assessing disease progression. Further studies on a larger group of patients are needed, as well as studies evaluating the correlation between other sagittal balance parameters and cervical instability in patients with RA.