Novel multimodal mechanical stimulation is superior to TENS to treat and prevent chronic low back pain: a randomized controlled trial

Abstract

Background: Low back pain (LBP) is the leading cause of disability worldwide. Up to half of moderate-to-severe acute LBP (aLBP) progress to chronic (cLBP), with neuromotor, fascial, and muscle pathology contributing to inoperable mechanical disability. A novel thermomechanical stimulation (M-Stim) device delivering stochastic and targeted vibration frequencies relieved LBP in a pilot. Efficacy versus an active control, for cLBP prevention, or reversing disability was undetermined.

Methods: As part of a National Institutes of Health (NIH) double-blind, randomized controlled trial, 159 chiropractic patients with non-radiating moderate-to-severe LBP [Numeric Rating Scale (NRS) ≥4] were randomized to add either the multimodal M-Stim device or 4-lead transcutaneous electrical nerve stimulation (TENS) for 30 minutes daily to other therapies. Between June 2022 and July 2024, pain scores, analgesic use, and device adherence were recorded for 28 days, with weekly follow-up up to 6 months. Primary outcomes included PROMIS Pain Interference scores, NRS pain scores, and transition from aLBP to cLBP (Pain Interference ≥55 at 3 months). Exploratory analyses examined higher-severity subgroups, including those meeting NIH Research Task Force (RTF) criteria, obesity, longer pain duration, and an integrated analysis with common criteria for intractable inoperable mechanical cLBP.

Results: For 44 aLBP and 115 cLBP participants [mean age 42.6, 54% female, BMI 30.9 (SD 6.19), NRS 5.51 (SD 2.15)], M-Stim was noninferior to TENS for initial and 10-day relief. Over time, Linear Mixed Models (intention-to-treat) showed M-Stim significantly improved pain and disability for both aLBP and cLBP, (p < .001 to p = .024). With higher severity, 23.9% (11/46) M-Stim users reached "no disability" (PROMIS = 40.7) vs. 7.1% (2/28) TENS users [RR 0.81 (95% CI 0.66-0.99), p = 0.04]. M-Stim yielded significantly greater improvement than TENS in those with pain ≥5 years, BMI ≥30, or mechanical cLBP (all p < .05). Significantly fewer aLBP M-Stim users transitioned to cLBP at 3 months [31.8% vs. 72.7%, RR 0.44 (95% CI 0.23-0.85), NNT = 2.4, p = 0.015].

Conclusions: A multimodal M-Stim device reduced progression to cLBP significantly more than TENS. Both devices reduced pain initially, but M-Stim reduced pain and disability significantly more over time, particularly in cLBP subsets with higher severity, duration, or BMI.

Clinical trial registration: https://clinicaltrials.gov/study/NCT04494698, identifier NCT04494698.

Keywords: PROMIS (patient-reported outcomes measurement information system); acute low back pain (aLBP); chronic low back pain (cLBP); focal mechanical vibration; mechanical low back pain; prevention; spine biomechanics; vibration.

Figure 1

Contoured temperature plate (1). Natural Clay Ice/Heat Pack (2). Multi-Vibration Motor Array (3). Trigger Point Acupressure Nubs (4). Five Intensity Settings (5). LED Cycle & Intensity Display (6). Magnetic Charging Cable (7). Eight Therapy Cycles (8). Custom Fit Waistband (9). Slide-N-Lock Magnetic Buckle (10). Haptic Touch Panel (11).

Figure 2

The consort flowchart acute and chronic Low back pain.

Figure 3

LMM change in NRS pain intensity over time. Baseline average NRS did not differ statistically for aLBP or cLBP. All NRS scores decreased significantly over the course of follow-up, with TENS decreasing less and significantly more slowly than M-Stim. All average predicted NRS endpoints showed resolution of NRS Pain Intensity except cLBP TENS subjects.

Figure 4

Disability reduction over time for cLBP cohort. (a) Using a Linear Mixed Model in ITT cohort, M-Stim regained function more rapidly. (b) Proportions of disability category for those completing ≥1 diary. (c) Mean disability scores by month for those with pain ≥5 years and completing ≥1 diary. (d) Disability scores RTF Moderate-to-Severe for those completing ≥1 diary. (e) Disability scores with 95%CI for those with BMI > 30 and completing ≥1 diary.

Figure 5

Disability reduction over time for acute pain cohort. For those with LBP duration <3 months, Pain Interference Disability Scores decreased over time. (a) LMM model using intention to treat, M-Stim users had more rapid resolution of disability. (b) Reduction with weekly SD for aLBP with ≥1 diary.

Figure 6

Acute pain baseline vs. Week 13 Disability. The relative risk of persistent pain at 13 weeks was significantly lower in the M-Stim group [RR = 0.44 (95% CI 0.23–0.85) p = 0.015, NNT = 2.4].

Figure 7

Thermal Use patterns in chronic participants by responder Status. Strong Responder (2.0) = zero (PROMIS = 40.7) disability AND >10-pt Improvement OR t-score below Moderate Disability AND >20-pt Improvement OR initial t-score Severe AND >15-pt Improvement. Mild Responder (1.0) has PROMIS ≤50 AND >5-pt improvements OR less than Moderate Disability AND >10-pt improvement OR initial Severe AND >10-pt Improvement. All others (0.0) are non-responders.