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Optimal doses of TENS, EA or LLLT provides short-term pain relief for knee osteoarthritis

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Optimal doses of TENS, EA or LLLT provides short-term pain relief for knee osteoarthritis

Vol: 2| Issue: 7| Number:168| ISSN#: 2564-2537
Study Type:Meta-analysis/Systematic Review
OE Level Evidence:1
Journal Level of Evidence:N/A

Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials

BMC Musculoskelet Disord. 2007 Jun 22;8:51

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This systematic review with meta-analysis for 36 randomized placebo-controlled trials looked at the efficacy of physical modalities (transcutaneous electrical stimulation - TENS, electro-acupuncture - EA, pulsed electromagnetic fields - PEMF, ultrasound - US, and low level laser treatment - LLLT) in patients with knee osteoarthritis (OA) pain within 1-4 weeks and at follow-up at 1-12 weeks after the treatment. The 36 RCTs identified had 2434 patients with a mean age of 65.1 years (1391 patients received active treatment). Results indicated that the optimal doses of TENS, EA and LLLT appear to offer short-term pain relief for knee OA.

Publication Funding Details +
Non-Industry funded
Norwegian Research Council
None disclosed

Risk of Bias


Reporting Criteria


Fragility Index


Were the search methods used to find evidence (original research) on the primary question or questions stated?

Was the search for evidence reasonably comprehensive?

Were the criteria used for deciding which studies to include in the overview reported?

Was the bias in the selection of studies avoided?

Were the criteria used for assessing the validity of the included studies reported?

Was the validity of all of the studies referred to in the text assessed with use of appropriate criteria (either in selecting the studies for inclusion or in analyzing the studies that were cited)?

Were the methods used to combine the findings of the relevant studies (to reach a conclusion) reported?

Were the findings of the relevant studies combined appropriately relative to the primary question that the overview addresses?

Were the conclusions made by the author or authors supported by the data and or analysis reported in the overview?

How would you rate the scientific quality of this evidence?

Yes = 1

Uncertain = 0.5

Not Relevant = 0

No = 0

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.




Accessing Data


Analysing Data





Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

Why was this study needed now?

The most common type of osteoarthritis (OA) is osteoarthritis of the knee. It is associated with pain and inflammation, loss of function, impaired muscle stabilization and reduced range of motion. There is uncertainty on the efficacy of non-pharmacological physical modalities on knee osteoarthritis pain. This systematic review and meta-analysis was needed to examine the short-term effects of physical modalities on OA pain.

What was the principal research question?

Does the use of physical modalities (transcutaneous electrical stimulation, electro-acupuncture, pulsed electromagnetic fields, ultrasound, low level laser treatment) offer clinically significant short-term pain relief for individuals with knee osteoarthritis?

Study Characteristics -
Data Source:
A search was conducted for randomized controlled trials using the online databases from 1966 to April 2006 on Medline, Embase, Cochrane Controlled Trials Register for RCTs, CINAHL, Database of Abstracts of Reviews of Effectiveness (DARE), International Network of Agencies for Health Technology Assessment (INAHTA) database, The Physiotherapy Evidence Database (PEDro), National Guideline Clearinghouse (NGC), PRODIGY Guidance, and NICE (National Institute for Clinical Excellence). Hand searches were also performed in the journal Laser Therapy from 1994, national Scandinavian physiotherapy journals, conference abstracts and reference lists of systematic reviews and books of abstracts after 1990 by the World Confederation of Physical Therapy and World Association for Laser Therapy. Finally, experts in the field were also consulted.
Index Terms:
"Osteoarthritis OR osteoarthrosis OR knee OR exercise OR electrotherapy OR laser therapy OR light therapy OR ultrasound OR electrostimulation OR transcutaneous electrical nerve stimulation OR electromagnetic AND randomized OR randomised"
Study Selection:
Studies included were randomized, placebo-controlled trials where patients underwent treatment for knee osteoarthritis (OA) with specified interventions. The specific inclusion criteria included 1. A diagnosis of knee osteoarthritis, 2. Symptom duration of >3 months, 3. Randomised blinded placebo-controlled parallel and cross-over groups trial design, 4. Outcome measures of pain intensity within 4 weeks of treatment start (primary) and 5 to 12 weeks follow-up (secondary), 5. Threshold levels for clinical relevance and 6. Intervention groups which included criteria for modality-specific optimal dosage (Acupuncture, low level laser therapy (LLLT), pulsed electromagnetic fields (PEMF), including shortwave therapy (SWT), PEMF other than SWT, electrical stimulation using surface electrodes (TENS), ultrasound therapy, static magnets, and placebo control groups). Two independent reviewers (JMB and RABL-M) assessed trial methodology. 36 trials investigating a total of 2434 patients (1391 actively treated) were selected.
Data Extraction:
The change in overall pain intensity between the active intervention group and placebo was used, however, if more than one attainable outcome measurement was obtained in the first 4 weeks after treatment started, the time point corresponding to the largest effect values was selected. If the aforementioned data was missing, data were obtained as a mean of the 5 items on the WOMAC pain subscale, or were converted to 100 mm VAS and checked against other subscales and overall WOMAC score.
Data Synthesis:
Outcomes were expressed as weighted mean differences (WMD) between the intervention and placebo groups with 95% confidence interval in the VAS scores. A fixed effects model was used. Q-values were used to test heterogeneity, and statistical significance for each intervention was defined at the 0.05. Revman 4.2 software package was used for statistical analysis.

What were the important findings?

  • Clinically relevant pain-relieving effects were seen with the use of transcutaneous electrical nerve stimulation (TENS) (18.8 mm [95% CI: 9.6 to 28.1]) (n=414), electro-acupuncture (EA) (21.9 mm [95%CI: 17.3 to 26.5]) (n=73) and low level laser therapy (LLLT) (17.7 mm [95% CI: 8.1 to 27.3]) (n=343) measured by VAS compared to the placebo.
  • When a subgroup analysis of trials was performed with assumed optimal doses, an increase in efficacy was seen. TENS had an increase to 22.2 mm [95%CI: 18.1 to 26.3], LTT had an increase to 24.2 mm [95%CI: 17.3 to 31.3] on VAS.
  • A small reduction in pain was seen when pulsed electromagnetic fields were used measured by VAS. (6.9 mm [95%CI: 2.2 to 11.6]) (n=487)
  • No statistically significant reduction in short-term pain was seen over the placebo at 4 weeks from the treatments of manual acupuncture, static magnets, and ultrasound therapies (p>0.05).
  • There was minimal follow-up data up to 12 weeks, but the outcome effects of TENS, EA, and LLLT seemed to persist for at least 4 weeks after the treatments ended.
  • The mean methodological quality scores over all the included trials was 3.8 out of a score of 5 on the Jadad scale.

What should I remember most?

The use of transcutaneous electrical nerve stimulation (TENS), electro-acupuncture (EA), and low level laser therapy (LLLT) at optimum doses in an intensive 2-4 week treatment program appeared to produce clinically relevant short-term pain relief in patients with knee osteoarthritis.

How will this affect the care of my patients?

Patients may find short-term pain relief from knee OA when they undergo a regimen of TENS, EA or LLLT. These physical therapies also appear to be a safe method of pain management for knee OA as no serious adverse events were reported in the RCTs reviewed. Based on this study, MA, PEMF, US and SM can not be recommended due to lack of efficacy on short-term pain relief for knee OA. Further high quality evidence is needed to support these findings.

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