Abstract

Introduction: For many people with chronic low back pain (CLBP), the root cause of the persistence of pain is disruption in control of the key muscles that stabilize the lumbar spine, particularly the lumbar multifidus. A feasibility study demonstrated that stimulation of the L2 medial branch to elicit episodic repetitive smooth contractions of the lumbar multifidi facilitated recovery from CLBP.

Purpose: ReActiv8-A is a prospective single arm clinical trial designed to evaluate a new implantable neurostimulation stimulation system (ReActiv8® by Mainstay Medical).

Materials and methods: Ten centers in Australia and Europe enrolled 92 subjects, of whom 47 proceeded to ReActiv8 implant and 46 reached the 90 day follow up. Key inclusion criteria included disabling CLBP (low back pain NRS ≥ 6) despite a minimum of 90 days of medical management including at least physical therapy and drugs, no prior spine surgery, and no indications for spine surgery or spinal cord stimulation. After the treatment activation visit, subjects were asked to administer two 30-min stimulation sessions per day for a minimum of 90 days.

At baseline, average duration of CLBP was 13.8 ± 10.3 years; average age was 43.9 ± 10.7 years. The majority of subjects (70%) were regularly taking opioids at baseline, and many were taking NSAIDS. The population had attempted all or most available treatments for their CLBP.

Results: At the 90 day follow up, 63% of subjects reported a ≥2 point improvement on single day NRS for average low back pain with a mean improvement of 2.3 ± 0.3 (33%) compared to baseline of 6.7 ± 0.2 (n = 46; p < 0.0001), and at 180 days it was 58% with a mean improvement of 2.1 ± 0.4 (30%) (n = 45, p < 0.0001). The proportion of subjects with a clinically important improvement in disability (≥10 point reduction in ODI) at 90 days was 57% with a mean improvement of 14.8 ± 2.3 (33%) compared to baseline of 46.4 ± 1.8 (n = 46, p < 0.0001), and at 180 days it was 60% with a mean improvement of 12.4 ± 2.4 (30%) compared to baseline of 45.2 ± 2.1 (n = 45, p < 0.0001).

Conclusion: These results show that subjects with disabling CLBP implanted with ReActiv8, experienced a clinically important, statistically significant and lasting improvement in their low back pain, related disability and quality of life.