Sacroiliac Joint Fusion With iFuse Implant System (SIFI)

Inclusion criteria

• Age 21-70 at time of screening

• Patient has lower back pain for >6 months inadequately responsive to conservative care

• Diagnosis of sacroiliac joint disruption or degenerative sacroiliitis based on ALL of the following:

• Patient has pain at or close to the posterior superior iliac spine (PSIS) with possible radiation into buttocks, posterior thigh or groin and can point with a single finger to the location of pain (Fortin Finger Test), and
• Patient has at least 3 of 5 physical examination maneuvers specific for the SI joint (see Table 3), and
• Patient has improvement in lower back pain numeric rating scale (NRS) of at least 50% after injection of local anesthetic into affected SI joint(s) (see Section 3.6.4), and
• One or more of the following:

i. SI joint disruption:

• Asymmetric SI joint widening on X-ray or CT scan
• Leakage of contrast on diagnostic arthrography

ii. Degenerative sacroiliitis:

• Radiographic evidence of SI joint degeneration, including sclerosis,osteophytes, subchondral cysts, or vacuum phenomenon on CT or plain film, or
• Due to prior lumbosacral spine fusion

• Baseline Oswestry Disability Index (ODI) score of at least 30% 5. Baseline SI joint pain score of at least 50 on 0-100 mm visual analog scale 6. Patient has signed study-specific informed consent form 7. Patient has the necessary mental capacity to participate and is physically able to comply with study protocol requirements

Exclusion criteria

• 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
• Other known sacroiliac pathology such as:

• Sacral dysplasia
• Inflammatory sacroiliitis (e.g., ankylosing spondylitis or other HLA-associated spondyloarthropathy)
• Tumor
• Infection
• Acute fracture
• Crystal arthropathy
• History of recent (< 1 year) major trauma to pelvis
• Previously diagnosed osteoporosis (defined as prior T-score <-2.5 or history of osteoporotic fracture).
• Osteomalacia or other metabolic bone disease
• Chronic rheumatologic condition (e.g., rheumatoid arthritis)
• Any condition or anatomy that makes treatment with the iFuse Implant System infeasible
• Chondropathy
• Known allergy to titanium or titanium alloys
• Use of medications known to have detrimental effects on bone quality and soft-tissue healing
• Prominent neurologic condition that would interfere with physical therapy
• Current local or systemic infection that raises the risk of surgery
• Patient currently receiving or seeking worker's compensation, disability remuneration, and/or involved in injury litigation.
• Currently pregnant or planning pregnancy in the next 2 years
• Patient is a prisoner or a ward of the state.
• Known or suspected drug or alcohol abuse
• Diagnosed psychiatric disease (e.g., schizophrenia, major depression, personality disorders) that could interfere with study participation
• Patient is participating in an investigational study or has been involved in an investigational study within 3 months prior to evaluation for participation