Multifidus PET Scan Study

Inclusion Criteria:

1. Age ≥22 years, ≤75 years

2. Low Back Pain VAS of ≥6.0cm and ≤9.0cm (on a 10cm scale) at the Baseline Visit.

3. Oswestry Disability Index score ≥21% and ≤60% at the Baseline Visit

4. Chronic Low Back Pain defined as pain and discomfort localized below the costalmargin and above the inferior gluteal fold (with or without referred leg pain) thathas persisted >90 days prior to the Baseline Visit, which has resulted in pain in atleast half of the days in the 12 months prior to the Baseline Visit, as reported bythe Subject.

5. Evidence of lumbar multifidus muscle dysfunction (for example by the ProneInstability Test (PIT)).

6. Continuing low back pain despite >90 days of medical management including:

7. At least one attempt of physical therapy treatment for low back pain, which mayoptionally be accomplished over multiple episodes or flare-ups of low backpain.

8. For Subjects with medications prescribed and used for chronic low back pain,usage shall be at a stable dose in the 30 days prior to the Baseline Visit asreported by the Subject. NOTE: A stable dose means the Subject reports no significant change in regular useof medications, which may include PRN use, in the 30 days prior to the BaselineVisit. Typical use must be provided

9. Be willing and capable of giving Informed Consent.

10. Ability to comply with the instructions for use and to operate ReActiv8, and tocomply with this Clinical Investigation Plan.

11. Suitable for ReActiv8 surgery as determined by the implanting physician prior toinclusion.

Exclusion Criteria:

1. BMI > 35

2. Back Pain characteristics:

3. Any surgical correction procedure for scoliosis at any time, or a currentclinical diagnosis of moderate to severe scoliosis (Cobb angle ≥25°).

4. Lumbar spine stenosis, as defined by an anterior-posterior diameter of thespinal canal <10mm in Subjects with lower extremity pain.

5. Neurological deficit possibly associated with the back pain (e.g. foot drop).

6. Back pain due to pelvic or visceral reasons (e.g.: endometriosis or fibroids)or infection (e.g.: post herpetic neuralgia).

7. Back pain due to inflammation or damage to the spinal cord or adjacentstructures (e.g. arachnoiditis or syringomyelia).

8. Pathology seen on MRI that is clearly identified and is likely the cause of theCLBP that is amenable to surgery.

9. Back pain due to vascular causes such as aortic aneurysm and dissection.

10. Leg pain described as being worse than back pain, or radiculopathy (neuropathicpain) below the knee.

11. Source of pain is the sacroiliac joint as determined by the Investigator.

12. Drug use per Subject report as follows: a. Current baseline use of >120mg oral morphine equivalent per day of opioids. b.Current use of breakthrough dose of >60mg oral morphine equivalent per day. c.Current requirement of opioids for treatment of a condition other than low backpain. d. History of any substance abuse at any time in the five years prior to theBaseline Visit. e. Currently taking >15mg Diazepam per day or equivalent.

13. Surgical or other procedures exclusions:

14. Any previous rhizotomy or rhizolysis procedure, including cryoablation, RFablation or pulsed RF on the dorsal root ganglion (DRG) or the medial branch ofthe dorsal ramus nerve that crosses or lies below the T8 vertebra, within oneyear prior to the Baseline Visit.

15. Anesthetic block of the DRG or medial branch of dorsal ramus nerve that crossesor lies below the T8 vertebra or injection of epidural steroids for back painin the 30 days prior to the Baseline Visit.

16. Any previous back surgery including laminectomy or discectomy at or belowsegmental level T8, or spinal fusion at any level.

17. Any previous thoracic or lumbar sympathectomy.

18. Any prior diagnosis of lumbar vertebral compression fracture, lumbar pars fracture,pars defect, or lumbar annular tear with disc protrusion that is amenable tosurgery.

9 Any co-morbid chronic pain conditions. 10. Other clinical conditions:

1. Pregnant or planning to be pregnant in the next 24 months, at the time of inclusion.

2. Pregnancy at any time in the 6 months, or lactating at any time in the 3 months,prior to the Baseline Visit.

3. Any condition unrelated to the CLBP such as muscle wasting, muscle atrophy, otherdisability (e.g.: paraplegic, amputee, cerebral palsy) or muscular or skeletaldisease (e.g.: arthritis in trunk or limbs, multiple sclerosis, rheumatoidarthritis) which, in the opinion of the Investigator, could limit physical movementor compliance with the protocol, or interfere with the assessment of efficacy of theinvestigational procedure.

4. Poorly controlled diabetes (Type I or Type II) determined by HbA1c >8.

5. Past or current neurological disorders (e.g.: known multiple sclerosis, motor neurondisease, Guillain-Barré syndrome, Parkinson's, Huntington's Disease, Alzheimer's,epilepsy, stroke, brain cancer, traumatic brain injury).

6. Cancer requiring treatment during the study.

7. Any drugs (e.g.: immunosuppressive drugs) or co-morbidity that might inhibit woundhealing or electrode scarring, or drugs associated with reduced effectiveness ofneuromodulation for other applications.

8. Any medical condition requiring anticoagulation (other than aspirin) that, in theopinion of the physician prescribing the anticoagulant, cannot be safely suspendedfor 5 days prior to device implantation surgery and an appropriate period afterimplantation surgery.

9. Any active infection in the vicinity of the implant site or any systemic infection.

10. Psycho-social exclusions:

a. Be involved in an injury claim under current litigation. b. Have a pending or approved financial compensation claim (e.g., worker's compensation claim, long term disability claims) or any financial compensation (including social welfare payments) related to the Subject's CLBP.

c. Current incarceration (prison or jail) d. Have an assessment of current active depression significant enough (DASS depression score >18 to impact perception of pain, compliance with intervention and/or ability to evaluate treatment outcome.

e. Have evidence of an active disruptive psychological or psychiatric disorder or other known condition significant enough to impact perception of pain, compliance with intervention and/or ability to evaluate treatment outcome (e.g.: active depression, bipolar disease, Alzheimer's disease) as determined by a psychologist or psychiatrist during the multidisciplinary team meeting to assess suitability of patients.

13. Protocol Compliance Exclusions:

a. Inability or unwillingness to comply with all protocol requirements. b. Inability to maintain the prone or side lying position in a relaxed manner for the duration of each stimulation session.

c. Inability to operate the Activator, such as arthritis that limits arm or shoulder movement, or inability to learn how to operate.

d. Inability to assess changes in pain intensity or perform wound care. e. Inability or unwillingness to complete the Pain score diary. 14. General exclusions:

1. Any other active implantable device including an implantable device for back pain (such as an implantable drug pump or Spinal Cord Stimulator), pacemaker, implantabledefibrillator, cochlear implant, deep brain stimulator, or other implantedneurostimulation device.

2. Prior exposure to an implantable neurostimulator for treatment of pain, includingspinal cord stimulation (including trial implant of SCS leads), occipital nervestimulation or peripheral nerve stimulation.

3. A condition currently requiring or likely to require use of MRI or diathermy whileimplanted with the ReActiv8.

4. Therapy with any investigational intervention (drugs, devices, or procedures) forthe treatment of back pain at the time of the Baseline Visit, or at any time in thepast if the past investigational intervention did not subsequently gain regulatoryapproval.

5. Current or planned participation in any clinical trial during participation in thisTrial.

6. Life expectancy <1 year.