Cryoneurolysis vs Radiofrequency Ablation for Chronic Sacroiliac Joint Pain

Inclusion Criteria: 1. Subjects at least 18 years of age at Screening 2. Primary complaint of buttock or axial low-back below L5 suggestive of unilateral or bilateral SIJ-mediated back pain 3. Positive SIJ provocative testing (at least two tests must be positive) 1. Thigh thrust test 2. Distraction test 3. Gaenslen's test 4. Compression test 5. Sacral thrust test 4. Low back or buttock pain is chronic (i.e., ≥ 3 months' duration) 5. Low back or buttock pain is moderate to severe (score of ≥ 4 to ≤ 9) on the 0 to 10 NRS at Screening 6. Low back or buttock pain causes functional impairment (≥ 30% on ODI) at Screening 7. Successful trial of one diagnostic sacroiliac joint block with local anesthetic and steroids that results in at least 50% relief of primary (index) pain for the duration of the local anesthetic used 8. Failure of at least three months of conservative non-operative therapy (e.g., physical therapy, chiropractic care, sleep hygiene, weight loss, spinal injections, NSAIDs, physician-directed exercise program or other appropriate analgesics) 9. Able to provide informed consent, adhere to the study visit schedule, and complete all study assessment Exclusion Criteria: 1. Active workers' compensation, personal injury, Social Security disability insurance (SSDI), or other litigation/compensation related to the spine 2. Serious spinal disorders (verified on magnetic resonance imaging (MRI)) that may impact outcomes, including any of the following: 1. Suspected cauda equina syndrome (e.g., bowel/bladder dysfunction) 2. Infection 3. Tumor 4. Traumatic fracture 5. Systemic inflammatory spondyloarthropathy 6. Lumbar radiculopathy/radiculitis (i.e., root irritation and deficit) 7. Neurogenic claudication 3. Prior SIJ fusion surgery across the SI joint 4. Comorbidity that, in the judgment of the Investigator, may affect the subject's ability to participate in the study including lumbar radiculopathy and neuropathic pain disorder 5. Currently pregnant, nursing, or planning to become pregnant during the study 6. Known contraindication to study device, including any of the following: 1. Cryoglobulinemia 2. Paroxysmal cold hemoglobinuria 3. Cold urticaria 4. Raynaud's disease 5. Open and/or infected wounds at or near the treatment site 6. Coagulopathy 7. Previous participation in an iovera° study 8. Severe chronic pain disorder that in the opinion of the investigator may impact study outcomes 9. Presence of any of the following: 1. Spinal neurostimulator 2. Intrathecal analgesic drug pump 10. Current manifestation of poorly controlled mental illness or catastrophizing that in the opinion of the investigator may meaningfully impact treatment outcomes, including any of the following: a. Mood disorder (e.g., depression, bipolar) i. Patient Health Questionnaire (PHQ-9) ≥ 12 at Screening b. Psychotic disorder (e.g., schizophrenia) c. Catastrophizing i. Pain Catastrophizing Scale (PCS) score \>30 at Screening 11. Subject received other spine interventions/therapies in the 30 days prior to block administration (e.g., spinal injections, minimally invasive therapies, surgical therapies) at the intended lumbar treatment levels 12. Subject received radiofrequency ablation ≤ 6 months before study enrollment at the intended treatment levels 13. History, suspicion, or clinical manifestation of: 1. Alcohol abuse or dependence 2. Illicit drug use 3. Opioid abuse or dependence (≥40 mg MED PO/day in past 30 days) Given the COVID-19 pandemic, the subject must be medically fit/cleared for surgery by the investigator. If there is a concern about a subject's recent or potential exposure to COVID-19, or if the subject is not medically fit/cleared for surgery due to suspected COVID-19 illness/symptoms (or other serious illness), the subject must be excluded per Exclusion criterion #4.