Is the Site of Back Pain Related to the Location of Magnetic Resonance Imaging Lesions in Patients With Chronic Back Pain? Results From the Spondyloarthritis Caught Early Cohort.

OBJECTIVE: To determine associations between magnetic resonance imaging (MRI) lesions originating from either axial spondyloarthritis (SpA) or from degeneration and pain in patients with chronic back pain of <2 years duration. METHODS: Patients from the Spondyloarthritis Caught Early (SPACE) cohort identified the sites of pain (thoracic, lumbar, buttock). The average MRI scores from 2 readers for axial SpA lesions and from 2 different readers for degenerative lesions were used. Associations between sacroiliac (SI) joint lesions and buttock pain were investigated by logistic regression analysis, and associations between axial SpA or degenerative lesions and pain in the spine (thoracic and lumbar) were investigated using generalized estimating equations. Interactions with sex, age, HLA-B27, and fulfillment of Assessment of SpondyloArthritis international Society (ASAS) criteria were tested. RESULTS: In 348 patients (126 males, 127 fulfilling ASAS criteria, mean age 29.4 years), spinal MRI (and SI joint images in 342) were available. Pain was localized in the thoracic spine (35.9%), the lumbar spine (82.5%), or in the buttock(s) (57.8%). Inflammatory lesions of the SI joint (odds ratio [OR] 1.06; P = 0.04) and erosions of the SI joint in patients <25 years (OR 1.16; P = 0.04) were associated with buttock pain. Axial SpA spinal lesions were not associated with pain. Modic type 1 lesions in patients >35 years (OR 5.19; P = 0.001), high-intensity zone lesions in females not fulfilling ASAS criteria (OR 5.09; P = 0.001), and herniation in various subgroups (OR range 2.07-4.66) were associated with pain. CONCLUSION: Specific degenerative lesions, but not typical axial SpA lesions, of the spine are associated with pain at the same location in some subgroups. Inflammatory lesions in the SI joint are associated with buttock pain.