Prevalence and clinical significance of lumbosacral transitional vertebra (LSTV) in a young back pain population with suspected axial spondyloarthritis: results of the SPondyloArthritis Caught Early (SPACE) cohort

Objective To determine in a cohort of young patients with suspected axial spondyloarthritis (axSpA), the prevalence of lumbosacral transitional vertebra (LSTV), its association with local bone marrow edema (BME) and lumbar spine degeneration, and the potential relationship with MRI findings and clinical signs of axSpA. Materials and methods Baseline imaging studies and clinical information of patients from the SPondyloArthritis Caught Early-cohort (back pain >= 3 months, <= 2 years, onset <45 years) were used. Two independent readers assessed all patients for LSTV on radiography, and BME-like and degenerative changes on MRI. Patients with and without LSTV were compared with regard to the prevalence of MRI findings and the results of clinical assessment using Chi-squared test or t test. Results Of 273 patients (35.1% male, mean age 30.0), 68 (25%) patients showed an LSTV, without statistical significant difference between patients with and without axSpA (p = 0.327). Local sacral BME was present in 9 out of 68 (13%) patients with LSTV and absent in patients without LSTV (p <0.001). Visual analogue scale (VAS) pain score and spinal mobility assessments were comparable. Conclusions LSTV is of low clinical relevance in the early diagnosis of axSpA. There is no difference between patients with and without LSTV regarding the prevalence of axSpA, pain and spinal mobility, and a BME-like pattern at the pseudoarticulation does not reach the SI joints