Sacroiliac joint pain accounts for 15-30% of chronic low back pain and is often underdiagnosed because symptoms overlap with lumbar disc disease, hip pathology, and lumbosacral radiculopathy. Etiology includes degenerative arthritis, post-traumatic instability, postpartum ligamentous laxity, ankylosing spondylitis, and adjacent segment disease after lumbar fusion to the sacrum. Diagnosis requires three positive provocative maneuvers (FABER, thigh thrust, distraction, compression, Gaenslen, sacral thrust) and confirmatory diagnostic SI joint injection providing greater than 50-75% pain relief.
Conservative management includes physical therapy targeting core stabilization and pelvic girdle musculature, sacroiliac belts, NSAIDs, and image-guided corticosteroid injections that may be repeated every 3-6 months. Radiofrequency ablation of the lateral branches of the sacral dorsal rami provides intermediate-term relief but does not address joint instability. When conservative measures fail beyond 6 months and diagnostic injection confirms the SI joint as the pain generator, surgical fusion is considered.
Minimally invasive SI joint fusion places 2-3 porous-coated triangular titanium implants (such as iFuse or Integra Triton) across the SI joint via a small lateral incision under fluoroscopic guidance. The triangular geometry resists rotation, the porous coating promotes osseointegration, and the device transverses the joint engaging both ilium and sacrum. Compared with traditional open arthrodesis, the percutaneous approach reduces blood loss, postoperative pain, hospital stay, and complication rates while achieving comparable pain relief and fusion rates. Outcomes from randomized trials show significant superiority over non-surgical management at 2 years, with sustained improvements in pain, disability, and quality of life. Complications include implant malposition, neurologic injury (sacral nerve roots, S1 disc penetration), infection, hematoma, and persistent pain in 10-15%. Bilateral involvement may require staged or simultaneous bilateral fusion.