Background MRI-lesions in the spine (and SI-joints) are frequent in patients (pts) with axial spondyloarthritis (axSpA) and other pathologies like degenerative disease. It is relevant to know whether MRI-lesions (either axSpA or degenerative changes) are related with the site of back pain.
Objectives To determine associations between MRI-lesions originating from either axSpA or degeneration and site of pain in pts with chronic back pain (CBP) of ≤2 years.
Methods Pts with CBP (≥3 months, ≤2 years, onset <45 years) included in the SPACE cohort indicated site(s) of pain (thoracic, lumbar, buttock). Average MRI-scores from two readers for axSpA lesions and from two other readers for degenerative lesions were used. Readers were blinded for clinical data and scores of the other readers. AxSpA lesions considered inflammatory and fatty lesions, erosions and syndesmophytes/ankylosis on MRI-SI and MRI-spine. In addition, sclerosis was scored on MRI-SI. Each vertebral unit was scored for disc degeneration (Pfirrmann class >2), high intensity zone (HIZ), herniation, Schmorls' nodes and Modic changes (type I and type II). In addition, degenerative disc disease (DDD) was defined as degenerative complex with disc degeneration, an HIZ and herniation in an intervertebral disc.
Associations between MRI-SI lesions and buttock pain were investigated by logistic regression. Associations between axSpA or degenerative lesions and pain in the spine (thoracic and lumbar) were investigated by multilevel analysis with generalized estimating equations, taking the level of the spine into account. Interactions with gender, age, HLA-B27 and fulfilment of ASAS axSpA criteria were tested.
Results In 348 pts (126 males, 127 fulfilling ASAS axSpA criteria, mean age 29.4 years) MRI-spine was available (in 342 pts also MRI-SI). Pain was present in thoracic (35.9%), lumbar (82.5%) spine and/or buttock (57.8%). The figure shows the significant associations between MRI-SI axSpA lesions and pain and between degenerative MRI-spine lesions and pain. AxSpA lesions on MRI-spine were not associated with pain at the same site (data not shown).
Conclusions Inflammatory axSpA lesions in the SI-joints were associated with buttock pain. Specific degenerative lesions -but not typical axSpA lesions- in the spine were associated with pain at the same location, especially in HLA-B27 negative pts without axSpA and pts ≥35 years.
Disclosure of Interest None declared