Validity and Reliability of Diagnostic Findings of SI Joint Blocking

Inclusion Criteria: 1. Age 21-75 at time of screening. 2. Patient has buttocks, groin and/or leg pain suspected to be from one SI joint (left or right). 3. Patient has positive Fortin finger test\*. 4. Patient has a current average SI joint pain rating of at least 5 on 0-10 numerical rating scale\*\*. 5. Patient has at least 3 positive physical SI joint examination findings in the targeted SI joint. 6. Investigator believes that diagnostic SI joint block is indicated now, and that no other (hip/back, etc.) diagnostic test is required at this time. 7. Patient has signed study-specific informed consent form. 8. Patient has the necessary mental capacity to participate and is physically able to comply with study protocol requirements (including avoiding taking pain medication 8 hours prior to and 4 hours after each scheduled block). Exclusion Criteria: 1. Patient has history of any surgical procedure of the targeted SI joint (except for prior RF ablation of the SI joint). 2. Patient has suspected bilateral SIJ pain and bilateral injections are indicated. 3. Patient has history of chronic pain syndrome (e.g., fibromyalgia). 4. Patient has any medical or other condition that would interfere with study participation or data validity. 5. Patient is currently pregnant. 6. Patient has known allergy to contrast used or local anesthetic used (bupivacaine). 7. Patient has had one or more steroid SI joint injection(s) of the targeted side in the last 3 months. 8. Patient is a prisoner or a ward of the state. 9. Patient is participating in another investigational study related to back or SI joint pain (Exclude if participating in trials other than the SIFI study (NCT01640353) or the INSITE Study (NCT01681004). Subjects on these two SI-BONE sponsored trials may be eligible for VaReFi.) 10. Patient is known or suspected drug or alcohol abuser. 11. Patient has known or suspected psychiatric disease (e.g., schizophrenia, major depression, personality disorders) that could interfere with study participation . 12. Patient is unable to isolate suspected SI joint pain to the SI joint but rather has generalized pain. 13. Patient has known or suspected alternative cause for pain at/near SI joint (e.g., lumbar disc degeneration, lumbar facet arthropathy, hip osteoarthritis or labral tear)