MRI of the transverse and alar ligaments in rheumatoid arthritis: feasibility and relations to atlantoaxial subluxation and disease activity.

INTRODUCTION: Dysfunctional transverse and alar craniovertebral ligaments can cause instability and osseous destruction in rheumatoid arthritis (RA). This study examined (1) the feasibility of high-resolution magnetic resonance imaging (MRI) of these ligaments in RA and (2) the relation between ligament high-signal changes and atlantoaxial subluxation and RA duration/severity. METHODS: Consecutive RA patients (n=46) underwent clinical examination, functional radiography, and high-resolution MRI. Two blinded radiologists rated MRI image quality, graded ligament high-signal changes 0-3 on proton-weighted sequences using an existing grading system, and assessed cervical spine rheumatic changes on short tau inversion recovery images. Agreement was analyzed using kappa and relations using multiple logistic regression. RESULTS: MRI images had good quality in 42 (91.3%) of 46 patients and were interpretable in 44 (32 women and 12 men, median age/disease duration 60.4/9.1 years). MRI grades 2-3 changes of the transverse and alar ligaments showed moderate and good interobserver agreement (kappa 0.59 and 0.78), respectively, and prevalence 31.8% and 34.1%. Such ligament changes were more frequent with increasing anterior atlantoaxial subluxation (p=0.012 transverse, p=0.028 alar), higher erythrocyte sedimentation rate (p=0.003 transverse), positive rheumatoid factor (p=0.002 alar), and neck pain (p=0.004 alar). CONCLUSION: This first study of high-resolution MRI of these ligaments in RA showed high feasibility and relations with atlantoaxial subluxation, RA disease activity, and neck pain. The clinical usefulness of such MRI needs further evaluation.

Assessment of SpondyloArthritis International Society criteria for axial spondyloarthritis in chronic back pain patients with a high prevalence of HLA-B27.

OBJECTIVE: The Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axial spondyloarthritis (SpA) allow SpA classification of HLA-B27-positive patients if ≥2 specific clinical SpA features are present. We investigated the performance of these clinical ASAS criteria in a population with a high prevalence of HLA-B27. METHODS: A total of 807 persons reporting chronic back pain (CBP) lasting for >4 weeks during a population survey underwent a clinical, laboratory, and radiologic evaluation. The ASAS criteria for axial SpA were then used to determine classification status. RESULTS: Only 332 patients (41% of all CBP patients) fulfilled the prerequisite ASAS definitions for CBP (duration of ≥3 months and onset at age <45 years). In this ASAS-defined CBP cohort (51% women, CBP onset at age 27.2 years, 17% HLA-B27 positive), ASAS classification criteria for axial SpA were met by 8.4% of patients. Radiographic SpA by the modified New York criteria was present in 2.4%, while 6% fulfilled the clinical arm of the ASAS SpA criteria only. One-fifth of patients with clinical SpA developed radiographic evidence of SpA after a median of 8 years. CONCLUSION: Application of the clinical ASAS classification criteria in an area with a high prevalence of HLA-B27 leads to significant increases in the prevalence of axial SpA compared to radiologic SpA among CBP patients. This increase in the prevalence of disease is likely to have significant ramifications for patient management and health care systems.