Effectiveness of Hybrid Form Impulse Therapy (HFIT) Compared to Traditional Transcutaneous Electronic Nerve Stimulation (TENS) in Patients with Chronic Low Back and Knee Pain: A Randomized Controlled Trial

Purpose: Physical therapy (PT) and conservative care are recommended first-line treatments for musculoskeletal (MSK) pain. While essential to high-quality care, these solutions often do not provide immediate or sufficient pain relief. Traditional transcutaneous electronic nerve stimulation (TENS) devices are often recommended; however, there is mixed evidence behind their effectiveness. A novel approach called hybrid form impulse therapy (HFIT) incorporates a priming pulse with a traditional TENS pulse width and frequency. This randomized controlled trial (RCT) aimed to compare the effectiveness of HFIT versus traditional TENS versus usual care among members of a digital MSK program.

Patients and methods: A three-arm RCT comparing HFIT versus TENS versus usual care was conducted. A total of 325 people with chronic back or knee pain who were members of a digital MSK program consisting of PT-guided exercise therapy, education, and coaching were randomized. Outcomes including pain, function, anxiety, and depression were examined at 1, 2, and 4 weeks (primary endpoint). Engagement was measured through exercise therapy (ET) sessions completed. Unadjusted and adjusted logistic generalized estimating equations were conducted.

Results: Adjusted per-protocol results at 4 weeks showed significantly lower odds of achieving pain improvement for both TENS (OR: 0.42, 95% CI: [0.19, 0.92]) and usual care (OR: 0.35, 95% CI: [0.17, 0.72]) groups, compared to HFIT group. Both HFIT and usual care users had significantly higher engagement than the TENS users (p=0.026 and p=0.002, respectively). No adverse events were reported throughout the study.

Conclusion: More participants of a digital MSK program who were randomized to the HFIT group experienced meaningful pain improvement at 4 weeks than participants who used TENS and usual care. HFIT can be an effective, non-pharmaceutical solution for relief as a complement to first-line treatments for patients with chronic back and knee pain.