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Short-wave therapy reduces pain related to knee osteoarthritis in the short term but does not improve physical function

Wang H, Zhang C, Gao C, et al. Effects of short-wave therapy in patients with knee osteoarthritis: A systematic review and meta-analysis. Clin Rehabil. 2017;31:660-71.

Review question

In people who have knee osteoarthritis, does short-wave therapy reduce pain or improve physical function?


Osteoarthritis is a disease of the joints and often occurs in knees. It develops when your joints lose the cartilage that protects the ends of your bones. Symptoms of knee osteoarthritis include pain, tenderness, joint stiffness, and worsening physical functioning. There is no cure, and it often gets worse over time.

There are various treatments for the symptoms of knee osteoarthritis. This review is about short-wave therapy. Short-wave therapy uses electromagnetic radiation and is noninvasive. It can be delivered in a continuous wave or pulsed wave form.

How the review was done

The researchers did a systematic review, searching for studies that were published up to October 2016. They found 8 randomized controlled trials with 542 people who were 42 to 85 years of age (mostly women).

The key features of the trials were:

  • people had knee osteoarthritis;
  • treatment was short-wave therapy, alone or combined with either routine care or exercise (with or without education or hot packs);
  • short-wave therapy was mostly compared with placebo (a short-wave therapy device that was not powered to provide radiation) and sometimes compared with treatment other than short-wave therapy (mainly exercise or routine care); and
  • most people were treated for 3 weeks (range 2 to 8 weeks) over 6 to 24 sessions.

What the researchers found

Compared with placebo or no short-wave therapy, short-wave therapy:

  • reduced pain at the end of treatment but not after up to 12 months of follow-up;
  • improved extensor muscle strength at the end of treatment; and
  • did not change physical function, knee stiffness, or flexor muscle strength.


In people with knee osteoarthritis, short-wave therapy reduces pain at the end of treatment but does not improve physical function.

Short-wave therapy vs control* in people with knee osteoarthritis


Number of trials (number of people)

Effect of short-wave therapy


6 trials (326 people)

Reduced pain at end of treatment.


3 trials (147 people)

No effect on pain at up to 3 months of follow-up.


2 trials (143 people)

No effect on pain at 6 to 12 months of follow-up.

Physical function

6 trials (377 people)

No effect on physical function at end of treatment.


4 trials (310 people)

No effect on physical function at up to 3 months of follow-up.


3 trials (247 people)

No effect on knee stiffness at end of treatment or at up to 3 months of follow-up.

Muscle strength

2 trials (80 people)

Improved extensor muscle strength but not flexor muscle strength at end of treatment.

*Control = placebo short-wave therapy (short-wave therapy device that was not powered to provide radiation) or treatment other than short-wave therapy.


A harmless, inactive, and simulated treatment.
Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

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