Reactiv8 Multifidus Muscle Stimulation for Chronic Low Back Pain

What is Reactiv8?

Reactiv8 is an innovative implantable neurostimulation device that treats chronic low back pain by electrically reactivating the multifidus muscles — the deep stabilising muscles of the lumbar spine that are frequently inhibited or deactivated in patients with chronic low back pain.

The multifidus is a critical spinal stabiliser. In chronic low back pain, the multifidus frequently undergoes neurological inhibition — it stops firing properly — leading to spinal instability, worsening pain, and a self-perpetuating cycle of pain and muscle dysfunction. Reactiv8 delivers precisely calibrated electrical pulses to the medial branch nerves that supply the multifidus, stimulating repeated muscle contractions and reactivating the normal spinal stability mechanism.

Reactiv8 is designed for patients with chronic low back pain who have failed conventional treatments including physiotherapy, medications, and spinal injections, and who are not suitable candidates for major spinal fusion surgery. It offers a reversible, adjustable surgical option with a strong evidence base from multiple clinical trials.

How is Reactiv8 Different from Spinal Cord Stimulation?

Traditional spinal cord stimulation (SCS) works by masking pain signals. Reactiv8 works differently — it does not mask pain but instead addresses the underlying cause of mechanical low back pain by restoring multifidus function and lumbar spinal stability. This is a fundamental distinction: Reactiv8 treats the biomechanical source of pain rather than modulating pain perception.

Who is a Candidate for Reactiv8?

• Chronic low back pain (greater than 6 months) with insufficient relief from conservative treatment
• Mechanical low back pain with evidence of multifidus dysfunction — typically demonstrated on MRI as multifidus atrophy or fatty infiltration
• Failure of physiotherapy, medications, and spinal injections
• Not suitable for, or not wishing to undergo, major spinal fusion surgery
• Willingness to participate in the required stimulation programme (two 30-minute sessions per day)

Patient selection is rigorous. A specialist assessment including clinical review, MRI evaluation of multifidus morphology, and psychological screening is required before Reactiv8 is recommended.

What Happens During Reactiv8 Implantation?

Reactiv8 implantation is a minimally invasive procedure performed under general or spinal anaesthesia as a day case or with a one-night stay. Through two small incisions in the lower back, leads are placed bilaterally next to the medial branch nerves at L2-L3 under fluoroscopic guidance. An implantable pulse generator (IPG) — approximately the size of a pacemaker — is placed subcutaneously in the flank or upper buttock through a separate small incision.

Correct lead placement is confirmed by intraoperative electromyographic assessment of multifidus contraction in response to stimulation. The procedure typically takes 1 to 2 hours. Most patients are discharged the same day or the following morning.

Using Reactiv8 — The Stimulation Programme

Following implantation and recovery, patients perform two daily 30-minute stimulation sessions. During each session, the Reactiv8 device delivers low-frequency electrical pulses that cause rhythmic multifidus contractions — effectively performing involuntary deep core muscle exercises. The device is programmed and adjusted using an external controller. Sessions are typically performed lying down for comfort during the stimulation.

The therapeutic effect develops over months as the multifidus progressively regains strength and activation. Clinical trials demonstrate continued improvement over 6 to 24 months.

Outcomes of Reactiv8

The ReActiv8-B randomised controlled trial (RCT) — the pivotal study for Reactiv8 — demonstrated significant and sustained reduction in low back pain and disability compared to a sham (inactive device) control group. At 120 days, 53% of patients in the treatment group achieved at least 50% improvement in back pain VAS score. Long-term follow-up at 2 years demonstrates continued clinically meaningful improvement in the majority of patients, with over 60% reporting significant pain relief.

Unlike many surgical spine procedures, Reactiv8 is reversible — the device can be reprogrammed, adjusted, or removed if required. It does not alter spinal anatomy.

Risks and Complications

• Surgical risks — wound infection (approximately 1%), haematoma, lead displacement requiring revision (approximately 5%)
• Stimulation side effects — discomfort from stimulation (usually addressed by reprogramming)
• Device malfunction — rare; devices carry manufacturer warranty
• Lead migration — uncommonly requires repositioning
• No effect — approximately one-third of patients do not achieve the target response; the device can be reprogrammed or removed