Iliac crest pseudoarticulation with the lumbar transverse process: Two cases, imaging considerations, and injection outcomes

Background Isolated pseudoarticulation between lumbar transverse processes and the iliac crest is rarely reported and may be distinct from Bertolotti's syndrome (fifth lumbar transverse process–sacral ala pseudoarticulation). This case series describes clinical presentation, imaging findings, and response to corticosteroid injection. Case presentations In the first case, the patient presented with diffuse low back pain. Imaging revealed a pseudoarticulation between the fourth lumbar transverse process and iliac crest. Image-guided corticosteroid injection produced substantial and durable pain relief. In the second case, the patient had right-sided axial low back pain, reproducible with palpation of the right posterior medial iliac crest and positive rotation–extension testing. Imaging showed bilateral pseudoarticulations between the fifth lumbar transverse processes and the proximal iliac crest. The same injection protocol provided significant but transient pain relief. Conclusion Isolated lumbar transverse process–iliac crest pseudoarticulation may be an under-recognized pain source. Targeted local anesthetic injections can serve as diagnostic tools for localization and prognostication for therapeutic injections.