Spinal-pelvic orientation: potential effect on the diagnosis of spondyloarthritis

Rheumatology (Oxford). 2020 Jan 1;59(1):84-89. doi: 10.1093/rheumatology/kez240.


Objective: To assess associations of spinal-pelvic orientation with clinical and imaging-study findings suggesting axial SpA (axSpA) in patients with recent-onset inflammatory back pain.

Methods: Spinal-pelvic orientation was assessed in DESIR cohort patients with recent-onset inflammatory back pain and suspected axSpA, by using lateral lumbar-spine radiographs to categorize sacral horizontal angle (<40° vs ⩾40°), lumbosacral angle (<15° vs ⩾15°) and lumbar lordosis (LL, <50° vs ⩾50°). Associations between these angle groups and variables collected at baseline and 2 years later were assessed using the χ2 test (or Fisher's exact) and the Mann-Whitney test. With Bonferroni's correction, P < 0.001 indicated significant differences.

Results: Of 362 patients, 358, 356 and 357 had available sacral horizontal angle, lumbosacral angle and LL values, respectively; means were 39.3°, 14.6° and 53.0°, respectively. The prevalence of sacroiliitis on both radiographs and MRI was higher in the LL < 50° group than in the LL ⩾50° group, but the difference was not statistically significant. Clinical presentation and confidence in a diagnosis of axSpA did not differ across angle groups. No significant differences were identified for degenerative changes according to sacral horizontal angle, lumbosacral angle or LL.

Conclusion: Spinal-pelvic balance was not statistically associated with the clinical or imaging-study findings suggesting axSpA in patients with recent-onset inflammatory back pain.

Keywords: ankylosing spondylitis; axial spondyloarthritis; lumbar lordosis; sacral slope; sacroiliitis.

MeSH terms

  • Adult
  • Back Pain / diagnostic imaging
  • Back Pain / physiopathology
  • Female
  • Humans
  • Lumbar Vertebrae / diagnostic imaging
  • Lumbar Vertebrae / physiopathology
  • Magnetic Resonance Imaging / statistics & numerical data*
  • Male
  • Orientation, Spatial
  • Pelvic Bones / diagnostic imaging
  • Pelvic Bones / physiopathology
  • Pelvimetry / statistics & numerical data*
  • Postural Balance
  • Prospective Studies
  • Radiography / statistics & numerical data*
  • Reproducibility of Results
  • Sacroiliitis / diagnostic imaging*
  • Sacroiliitis / physiopathology
  • Spondylarthritis / diagnostic imaging*