Aquatic exercise for people with osteoarthritis in the knee or hip

Review question

What are the effects of aquatic exercise interventions in the treatment of people with knee and hip osteoarthritis (OA)?

Background: what is osteoarthritis of the hip and knee, and what is aquatic exercise?

Osteoarthritis is a chronic disease characterized by joint pain, tenderness, and limitation of movement. At present no cure is available. Thus only treatment of the person's symptoms and treatment to prevent further development of the disease are possible. Aquatic exercise is physical exercises taking place while the participant are immersed in water, typically water with a temperature between 32°C to 36°C. This is a review update of a published Cochrane review, and presents results from research concerning the effect of aquatic exercise for treating people with the knee and hip osteoarthritis.

Study characteristics

In this summary of this Cochrane review update we present what we know from research about the effects of aquatic exercise for people with osteoarthritis of the knee and hip. After searching for all relevant trials up to 28 April 2015, we included nine new trials since the last version of the Cochrane review. In total we included 13 trials (1190 participants). Most of these trials included participants with mild to moderate symptomatic knee or hip osteoarthritis.

Key results

Aquatic exercise for a mixed group of people with knee and hip osteoarthritis probably improves pain, disability slightly, and may improve quality of life slightly immediately after completion of a treatment course (up to 12 weeks of aquatic exercise). This review update does not change the conclusions of the previous published version of this Cochrane review.

Pain [lower score is better]

People who completed an aquatic exercise programme rated their pain as five points lower (three to eight points lower) on a 0 to 100 scale at the end of aquatic exercise compared with people who did not receive aquatic exercise (5% absolute improvement)

People who completed an exercise program rated their pain to be 41 points on a scale of 0 to 100

People in the control group rated their pain to be 46 points on a scale of 0 to 100.

Disability [lower score is better]

People who completed an aquatic exercise programme rated their disability as five points lower (three to eight points lower) on a 0 to 100 scale at the end of aquatic exercise compared with people who did not receive aquatic exercise (5% absolute improvement)

People who completed an exercise program rated their disability to be 39 points on a scale of 0 to 100

People in the control group rated their disability to be 44 points on a scale of 0 to 100

Quality of life [higher score is better]

People who completed an aquatic exercise programme rated their quality of life as seven points higher (0 to 13 points higher) on a 0 to 100 scale at the end of aquatic exercise compared with people who did not receive aquatic exercise (13% absolute improvement)

People who completed an exercise program rated their quality of life to be 57 points on a scale of 0 to 100

People in the control group rated their quality of life to be 50 points on a scale of 0 to 100

X-rays of the joints - no studies measured this outcome

Withdrawals from the study

3 more people out of 100 dropped out of the aquatic exercise programme (3% absolute increase)

18 people out of 100 in the aquatic exercise group dropped out of the exercise programme

15 people out of 100 dropped out of the control group

Serious adverse events

No serious side effects were reported with relation to participating in aquatic exercise

Quality of evidence

Moderate quality evidence shows that among people with hip and knee osteoarthritis, aquatic exercise may reduce pain and disability, and increase quality of life immediately after the end of the programme of treatment. Further research may change these results.

Authors' conclusions: 

There is moderate quality evidence that aquatic exercise may have small, short-term, and clinically relevant effects on patient-reported pain, disability, and QoL in people with knee and hip OA. The conclusions of this review update does not change those of the previous published version of this Cochrane review.

Read the full abstract...
Background: 

Osteoarthritis is a chronic disease characterized by joint pain, tenderness, and limitation of movement. At present, no cure is available. Thus only treatment of the person's symptoms and treatment to prevent further development of the disease are possible. Clinical trials indicate that aquatic exercise may have advantages for people with osteoarthritis. This is an update of a published Cochrane review.

Objectives: 

To evaluate the effects of aquatic exercise for people with knee or hip osteoarthritis, or both, compared to no intervention.

Search strategy: 

We searched the following databases up to 28 April 2015: the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library Issue 1, 2014), MEDLINE (from 1949), EMBASE (from 1980), CINAHL (from 1982), PEDro (Physiotherapy Evidence Database), and Web of Science (from 1945). There was no language restriction.

Selection criteria: 

Randomized controlled clinical trials of aquatic exercise compared to a control group (e.g. usual care, education, social attention, telephone call, waiting list for surgery) of participants with knee or hip osteoarthritis.

Data collection and analysis: 

Two review authors independently selected trials for inclusion, extracted data and assessed risk of bias of the included trials. We analysed the pooled results using standardized mean difference (SMD) values.

Main results: 

Nine new trials met the inclusion criteria and we excluded two earlier included trials. Thus the number of participants increased from 800 to 1190 and the number of included trials increased from six to 13. Most participants were female (75%), with an average age of 68 years and a body mass index (BMI) of 29.4. Osteoarthritis duration was 6.7 years, with a great variation of the included participants. The mean aquatic exercise duration was 12 weeks. We found 12 trials at low to unclear risk of bias for all domains except blinding of participants and personnel. They showed that aquatic exercise caused a small short term improvement compared to control in pain (SMD −0.31, 95% CI −0.47 to −0.15; 12 trials, 1076 participants) and disability (SMD −0.32, 95% CI −0.47 to −0.17; 12 trials, 1059 participants). Ten trials showed a small effect on quality of life (QoL) (SMD −0.25, 95% CI −0.49 to −0.01; 10 trials, 971 participants). These effects on pain and disability correspond to a five point lower (95% CI three to eight points lower) score on mean pain and mean disability compared to the control group (scale 0 to 100), and a seven point higher (95% CI 0 to 13 points higher) score on mean QoL compared with control group (scale 0 to 100). No included trials performed a radiographic evaluation. No serious adverse events were reported in the included trials with relation to aquatic exercise.

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