iFuse TORQ for the Treatment of Sacroiliac Joint Dysfunction (STACI) is a prospective, multicenter, study of SIJ fusion using the iFuse TORQ implant system.

This trial is a prospective, multicenter, study of SIJ fusion using the iFuse TORQ implant system. The goal of the trial is to demonstrate the effectiveness of the device for its intended use.

Inclusion Criteria:

1. Age > 21 at time of screening
2. Patient has lower back / buttock pain for at least 6 months inadequately responsive to non-surgical care
3. Diagnosis of sacroiliac joint dysfunction (degenerative sacroiliitis or sacroiliac disruption)
4. Baseline Oswestry Disability Index (ODI) score of at least 30%
5. Baseline SIJ pain score of at least 5 on 0-10 numerical rating scale
6. BMI < 35
7. Patient has signed study-specific informed consent form

Exclusion Criteria:

1. ASA score 4 or 5
2. Severe back pain due to other causes, such as lumbar disc degeneration, lumbar disc herniation, lumbar spondylolisthesis, lumbar spinal stenosis, lumbar facet degeneration, and lumbar vertebral body fracture
3. Other known sacroiliac pathology such as: inflammatory sacroiliitis (e.g., ankylosing spondylitis or other HLA-associated spondyloarthropathy), tumor, infection, acute fracture
4. Cluneal neuralgia
5. Previous SIJ implant placement, including allograft
6. Anatomic anomalies/defects that would preclude safe and/or biomechanically acceptable device placement
7. History of recent (<1 year) major trauma to pelvis
8. Previously diagnosed or suspected severe osteoporosis (defined as prior T-score < -2.5 or history of osteoporotic fracture).
9. Chronic rheumatologic condition (e.g., rheumatoid arthritis)
10. Current diagnosis of fibromyalgia
11. Known allergy to titanium or titanium alloys
12. Current local or systemic infection that raises the risk of surgery
13. Patient currently receiving or seeking worker's compensation, disability remuneration, and/or involved in injury litigation
14. Currently pregnant or planning pregnancy in the next 2 years (self-reported)
15. Patient is a prisoner or a ward of the state.
16. Known or suspected active drug or alcohol abuse, including opioids
17. Diagnosed psychiatric disease (e.g., schizophrenia, major depression, personality disorders) that could interfere with study participation
18. Currently participating in another interventional clinical trial