Pseudo-joint Pain From Lumbosacral Transitional Vertebra Mimicking Sacroiliac Joint Pain: A Case Report

Abstract Lumbosacral transitional vertebra (LSTV) can produce pseudo-joint arthropathy, often mimicking sacroiliac joint (SIJ) pain on clinical examination. Here, we present the case of a 30-year-old female with chronic low back pain and multiple positive SIJ provocative tests. Although SIJ dysfunction was strongly suspected, a fluoroscopy-guided SIJ diagnostic block produced no significant pain relief, ruling out SIJ as the pain generator. In contrast, a pseudo-joint block at the LSTV articulation resulted in >50% immediate pain relief, confirming pseudo-joint-mediated pain. This case report emphasizes the diagnostic limitations of clinical tests alone and underscores the importance of targeted diagnostic blocks to correctly identify LSTV-related pain.