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Study summary · Pain, nerves & musculoskeletal medicine

Does transcutaneous electrical nerve stimulation (TENS) effectively relieve pain and improve physical function in patients with knee osteoarthritis compared to placebo TENS, and is it safe?

Osteoarthritis Cartilage · 2021 · PMID 34826572 · DOI 10.1016/j.joca.2021.10.015

Plain-English summary written and published by Magellan Longevity · medical review by Gabriel Radu, DO (physiatrist, NPI 1376861765). We summarize what the paper reported — we did not run this study.

The takeaway

TENS is not more effective than placebo for relieving knee pain in osteoarthritis and does not improve physical function.

The question

Does transcutaneous electrical nerve stimulation (TENS) effectively relieve pain and improve physical function in patients with knee osteoarthritis compared to placebo TENS, and is it safe?

What they tested

The study implicitly hypothesizes that TENS will be more effective than placebo TENS in reducing knee pain and improving physical function, and will be safe.

How they did it

This was a multi-centre, parallel, 1:1 randomized, double-blind, placebo-controlled clinical trial. 220 participants with knee osteoarthritis were randomized to receive either TENS (n=108) or placebo TENS (n=112) for 3 weeks. The primary endpoint was knee pain at 3 weeks, assessed by the WOMAC pain subscale, with secondary outcomes including the WOMAC physical function subscale and safety.

What they found

There was no significant difference in WOMAC pain between TENS and placebo TENS at the end of treatment (mean difference -0.06; P = 0.74) or throughout the trial (P = 0.98). Subgroup analyses also showed no interaction between patient/treatment characteristics and treatment effect on pain. Adverse event rates were similar, with 10.4% in the TENS group and 10.6% in the placebo TENS group (P = 0.95). No relevant differences were observed in secondary outcomes.

Adverse Events in TENS vs. Placebo TENS Groups
Values shown: Percentage of Patients (%)
TENS Group10.4
Placebo TENS Group10.6

Percentage of patients reporting adverse events in the TENS and placebo TENS groups.

What it means

TENS does not improve knee osteoarthritis pain compared to placebo TENS. Therapists should consider alternative treatments for knee osteoarthritis pain and to facilitate exercise.

Limitations

The abstract does not explicitly state limitations of the study, but rather emphasizes the conclusiveness of its findings.

Where the published abstract does not list limitations, we say so rather than inventing them. Read the full paper on PubMed before drawing conclusions.

“patients were randomized to TENS or placebo TENS for knee osteoarthritis”— from the published abstract, Osteoarthritis Cartilage 2021

The paper at a glance

TitleEffect of transcutaneous electrical nerve stimulation on knee pain and physical function in osteoarthritis: a randomized clinical trial
JournalOsteoarthritis Cartilage
Year2021
PMID34826572 ↗
DOI10.1016/j.joca.2021.10.015 ↗
TopicPain, nerves & musculoskeletal medicine

Read the source: PubMed record (authors, abstract, full citation) ↗ · Publisher via doi.org ↗

Where Magellan uses this paper

This citation sits behind the evidence grade on the pages below. Grades are set from the research and are independent of affiliate commissions.

TENS Pain-Relief Unit

Evidence on TENS is mixed but, on balance, supportive for short-term pain relief. The largest synthesis (381 randomized trials) found pain intensity lower during or immediately after TENS versus placebo, and randomized trials and meta-analyses report benefits for fibromyalgia, post-surgical pain (with reduced opioid…

TENS Pain-Relief Unit

Transcutaneous electrical nerve stimulation (TENS) is a non-invasive, portable method of pain relief in…

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Molecules & mechanisms in this paper

Each of these is named in the paper’s own words above. Open the monograph for the full mechanism and its other citations.

Cite this page

These citations point at this summary. To cite the original paper with its full author list, use the PubMed record or doi.org.

APA
Magellan Longevity. (2026). Does transcutaneous electrical nerve stimulation (TENS) effectively relieve pain and improve physical function in patients with knee osteoarthritis compared to placebo TENS, and is it safe? [Plain-English summary of Osteoarthritis Cartilage 2021, PMID 34826572, DOI 10.1016/j.joca.2021.10.015]. Magellan Longevity. https://magellanlongevity.com/study/d34826572.html
BibTeX
@misc{magellan_d34826572, title = {Does transcutaneous electrical nerve stimulation (TENS) effectively relieve pain and improve physical function in patients with knee osteoarthritis compared to placebo TENS, and is it safe?}, author = {{Magellan Longevity}}, year = {2026}, howpublished = {\url{https://magellanlongevity.com/study/d34826572.html}}, note = {Plain-English summary of PubMed PMID 34826572; DOI 10.1016/j.joca.2021.10.015; Osteoarthritis Cartilage 2021. Reviewed by Gabriel Radu, DO}, urldate = {2026-08-11} }
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How this summary was made. Every section above restates what the published abstract of PMID 34826572 reports — the question, the design, the numbers, the authors’ own conclusion and their stated limitations. We do not add claims the paper did not make, and we keep negative and no-effect findings in. Magellan’s evidence grades are set from research like this and never from affiliate commissions.

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Educational information, not medical advice. This is a plain-English summary of published research; it is not a treatment recommendation and nothing here is intended to diagnose, treat, cure, or prevent any disease. Individual studies can be wrong, and a single paper rarely settles a question. Talk to your physician before acting on any research, especially if you are pregnant, nursing, or taking medication.