Chief of Spine Division Duke University Durham, North Carolina, United States
Disclosure(s):
Christopher I. Shaffrey, MD, FAANS: Depuy: Research Grant (Ongoing); Medtronic: Consultant (Ongoing), Research Grant (Ongoing), Royalty Recipient (Ongoing); Neurosurgery RRC: Research Grant (Ongoing); NuVasive: Advisor (Ongoing), Consultant (Ongoing), Royalty Recipient (Ongoing), Stock Shareholder (excluding mutual funds) (Ongoing); Proprio: Consultant (Ongoing), Stock Shareholder (excluding mutual funds) (Ongoing)
Introduction: Chronic low back pain (CLBP) can be caused by impaired neuromuscular control of the multifidus muscles, the most important stabilizers of the lumbar spine. An implantable Restorative Neurostimulation system (ReActiv8® by Mainstay Medical) stimulates the L2 medial branches to activate the multifidus and facilitate motor control restoration. A randomized sham-controlled pivotal trial provided evidence of safety, effectiveness, and durability of this therapy (clinicaltrials.gov/show/NCT02577354).1,2 Few if any prospective neuromodulation trials have shared efficacy, safety, and participant accountability outcomes beyond two years. Here we report the four-year results.
Methods: Eligible patients had activity limiting CLBP (VAS ≥6cm; Oswestry Disability Index (ODI) ≥21 points) despite medical management, which included at least pain medications and physical therapy. They had evidence of impaired multifidus motor control (positive prone instability test) and no indication for spine surgery.
Results: At baseline (N=204), participants were 47±9 years of age, had history of backpain for 14±11 years, had an average low back pain VAS of 7.3±0.7 cm, ODI of 39±10, EQ-5D of 0.585±0.174 points and had pain on 97±8% of days in the year prior to enrollment.
At 4 years (N=105*), mean VAS had improved by 5.0±2.3 cm, ODI by 23.8±14.4 points and EQ-5D by 0.247±0.206 (P < 0.0001 for all); 73% of participants had ≥50% VAS improvement; 64% reported LBP-Resolution (VAS≤2.5 cm); 64% had ≥20-point ODI improvement; and 80% had ≥50% improvement in VAS and/or ≥20 points in ODI. Of participants using opioids, 76% had voluntarily discontinued or decreased consumption. A total of 11/204 (5%) participants requested device removal after resolution of pain and 26/204 (13%) for inadequate pain relief. The overall safety profile is favorable, and no lead migrations were observed.
Conclusion : Restorative-Neurostimulation is effective, durable, and safe treatment for patients with activity-limiting CLBP associated with multifidus muscle dysfunction.
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