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.