Clinical Diagnosis Supersedes Imaging in Sacroiliac Joint Pain: A Case Report of Magnetic Resonance Imaging-negative Patient Successfully Treated with Cooled Radiofrequency Ablation

Sacroiliac (SI) joint dysfunction is a frequent yet underdiagnosed source of chronic low back pain, often missed when clinicians rely mostly on imaging. A 31-year-old male with left-sided low back pain for 2 years had three positive SI joint provocative tests but normal SI joint magnetic resonance imaging (MRI) findings. A fluoroscopy-guided diagnostic block with lidocaine produced immediate >70% pain relief, confirming SI joint pain. Cooled radiofrequency ablation (CRFA) of L5 dorsal ramus and S1–S3 lateral branches resulted in 80% pain reduction and functional recovery at 4 weeks. A normal MRI does not exclude SI joint pathology. Diagnosis should rely on clinical findings and diagnostic blocks, with CRFA offering long-term pain relief.