Therapeutic ultrasound for osteoarthritis

This summary of a Cochrane review presents what we know from research about the effect of therapeutic ultrasound on knee or hip osteoarthritis. The previous version of this review concluded that therapeutic ultrasound had no benefit over fake therapeutic ultrasound in pain relief and functional status.

The updated review shows that in people with osteoarthritis,
-Therapeutic ultrasound may be beneficial for people with osteoarthritis of the knee.

-Therapeutic ultrasound may improve your physical function but this finding could be the result of chance.

- We are uncertain about the magnitude of effects on pain relief or the ability to use your knee, because of the low quality of the evidence.
-Therapeutic ultrasound may not have any side effects: no side effects were reported, but we do not have precise information about side effects. This is particularly true for rare but serious side effects. 

There are no studies that address the benefits of therapeutic ultrasound in people with hip osteoarthritis.

What is osteoarthritis and what is therapeutic ultrasound?

Osteoarthritis is a disease of the joints, such as your knee or hip. When the joint loses cartilage, the bone grows to try and repair the damage. Instead of making things better, however, the bone grows abnormally and makes things worse. For example, the bone can become misshapen and make the joint painful and unstable.  This can affect your physical function or ability to use your knee.
Therapeutic ultrasound means using sound waves to try and relieve pain or disability. Your doctor or physiotherapist will use a round-headed wand or probe on the skin of the painful area. Ultrasound gel is used on the wand and on your skin to make it more comfortable and help the sound waves reach the affected area. 

Best estimate of what happens to people with osteoarthritis who have had therapeutic ultrasound for a duration of 2-8 weeks:

Pain
-People who used therapeutic ultrasound had an improvement in their pain of about 3 on a scale from 0 (no pain) to 10 (extreme pain) after using it up to 2 months.
-People who used a fake therapeutic ultrasound had an improvement in their pain of about 2 on a scale from 0 to 10 after using it up to 2 months.
Another way of saying this is:
- 37 people out of 100 who use therapeutic ultrasound respond to treatment (37%).
- 31 people out of 100 who use fake therapeutic ultrasound respond to treatment (31%).
- 6 more people respond to treatment with therapeutic ultrasound than with fake therapeutic ultrasound (difference of 6%).

Authors' conclusions: 

In contrast to the previous version of this review, our results suggest that therapeutic ultrasound may be beneficial for patients with osteoarthritis of the knee. Because of the low quality of the evidence, we are uncertain about the magnitude of the effects on pain relief and function, however. Therapeutic ultrasound is widely used for its potential benefits on both knee pain and function, which may be clinically relevant. Appropriately designed trials of adequate power are therefore warranted.

Read the full abstract...
Background: 

Osteoarthritis is the most common form of joint disease and the leading cause of pain and physical disability in the elderly. Therapeutic ultrasound is one of several physical therapy modalities suggested for the management of pain and loss of function due to osteoarthritis (OA).

Objectives: 

To compare therapeutic ultrasound with sham or no specific intervention in terms of effects on pain and function safety outcomes in patients with knee or hip OA.

Search strategy: 

We updated the search in CENTRAL, CINAHL, EMBASE, MEDLINE and PEDro up to 23 July 2009, checked conference proceedings, reference lists, and contacted authors.

Selection criteria: 

Studies were included if they were randomised or quasi-randomised controlled trials that compared therapeutic ultrasound with a sham intervention or no intervention in patients with osteoarthritis of the knee or hip.

Data collection and analysis: 

Two independent review authors extracted data using standardized forms. Investigators were contacted to obtain missing outcome information. Standardised mean differences (SMDs) were calculated for pain and function, relative risks for safety outcomes. Trials were combined using inverse-variance random-effects meta-analysis.

Main results: 

Compared to the previous version of the review, four additional trials were identified resulting in the inclusion of five small sized trials in a total of 341 patients with knee OA. No trial included patients with hip OA. Two evaluated pulsed ultrasound, two continuous and one evaluated both pulsed and continuous ultrasound as the active treatment. The methodological quality and the quality of reporting was poor and a high degree of heterogeneity among the trials was revealed for function (88%). For pain, there was an effect in favour of ultrasound therapy, which corresponded to a difference in pain scores between ultrasound and control of -1.2 cm on a 10-cm VAS (95% CI -1.9 to -0.6 cm). For function, we found a trend in favour of ultrasound, which corresponded to a difference in function scores of -1.3 units on a standardised WOMAC disability scale ranging from 0 to 10 (95% CI -3.0 to 0.3). Safety was evaluated in two trials including up to 136 patients; no adverse event, serious adverse event or withdrawals due to adverse events occurred in either trial.

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