This is a prospective, randomized, two-arm, phase II study.

The purpose of this study is:

• To evaluate and compare the efficacy and safety of magnetic resonance-guided focused ultrasound (MRgFUS) and radiofrequency ablation (RFA) for treatment of facet-joint osteoarthritis low back pain.
• Determining the effect of the MRgFUS System and RFA for improving functional disabilities and in reducing pain resulting from facet-joint osteoarthritis low back pain. Efficacy will be determined by the level of pain relief (as measured by the Numerical Rating Scale, NRS), decrease in analgesics/opiate, improved quality of life (as measured by the Oswestry Disability Questionnaire, ODQ, and core outcome measures index questionnaire, COMI), pain interference with function (as measured by the Brief Pain Inventory-Interference scale, BPI-QoL), general health status (as measured by the EQ5D), physical exam, X-ray and MRI studies from baseline up to 12-Months post- MRgFUS and radiofrequency treatment.
• Evaluate incidence and severity of adverse events associated with the MRgFUS system and RFA used for the treatment of pain resulting from facet-joint osteoarthritis low back pain.

Inclusion Criteria:

1. Men and women age 20 to 79 years old
2. Suffering from lumbar vertebral facet joint syndrome.
3. Lower back pain at least six months (NRS≥4).
4. Conventional treatment of pain includes NSAIDs, opioids, muscle relaxants, oral steroids, physical therapy or chiropractic therapy.
5. Imaging of the spine have facet osteoarthritis.
6. Referred pain is no more below the knee.
7. At least once when local anesthesia or diagnostic medial nerve branch injection, pain reduction> 75% (0.5ml of 2% lidocaine).

Exclusion Criteria:

1. Patients with evidence of lumbosacral radiculopathy on MRI, CT or physical exam findings, including radicular leg pain.

2. Patients with motor deficit or any other indication for surgical intervention.

3. Patients with MRgFUS or RF treatment for LBP within the last 6 months.

4. Patients with previous low back surgery.

5. Patients who are pregnant.

6. Patients with existing malignancy.

7. Patients with allergies to relevant contrast, anesthetics, sedation drugs.

8. Patients with contraindications for MRI.

9. Patients with an acute medical condition (e.g., pneumonia, sepsis) that is expected to hinder them from completing this study.

10. Patients with unstable cardiac status including:

    • Unstable angina pectoris on medication
    • Patients with documented myocardial infarction less than 40 days prior to protocol enrolment
    • Patients with Severe Congestive Heart Failure, NYHA class 4.
    • Patients on anti-arrhythmic drugs or with uncontrolled and/or untreated arrhythmia status
    • Patients with pacemaker

11. Patients with severe cerebrovascular disease (CVA within last 6 months)

12. Patients with severe hypertension (diastolic BP > 100 on medication)

13. Patients with an active infection or severe hematological, neurological, or other uncontrolled disease.

14. Patients unable to communicate with the investigator and staff.

15. Patients who are not able or willing to tolerate the required prolonged stationary position during treatment (approximately 2 hrs.)

16. Coagulation disorders or other bleeding disorders, use of anticoagulants or antiplatelet drugs within 5 days before treatment.

17. When local anesthesia or diagnostic medial nerve branch injection, the pain does not reach 75% (0.5 mL of 2% lidocaine).