Hydrotherapy Helpful in Osteoarthritis

Posted: 11/26/2003

Nov. 26, 2003 --- Water-based and land-based exercise programs both provide functional improvements over control for patients with osteoarthritis (OA), according to the results of a randomized trial published in the December issue of the Annals of the Rheumatic Diseases. Although strength gain was greater on land, the investigators suggest that water therapy should be used to improve aerobic capacity in those unable to do so on land, and that further studies are needed to demonstrate long-term benefits.

"Muscle atrophy is either a consequence of, or a risk factor for, OA and is not simply due to patients avoiding loading painful osteoarthritic knee joints," write Amanda Foley, from Flinders University in South Australia, and colleagues. "Land-based exercise regimens and strengthening exercise programmes have reported positive improvements in functional performance and reduction of the pain of OA."

In this single-blind, three-arm trial, 105 community-dwelling subjects aged 50 years and older with clinical OA of the hip or knee were randomized to receive hydrotherapy, gym-based resistance exercise, or no exercise. The hydrotherapy and gym groups had three exercise sessions weekly for six weeks, followed by outcome assessments by an independent, blinded physiotherapist. Drug use and compliance rates were similar in both exercise groups, with attendance at 84% of hydrotherapy and at 75% of gym sessions.

Compared with the control group, the gym group had better walking speed and self-efficacy satisfaction, and significant increases in bilateral quadriceps strength. Right quadriceps strength was also significantly better than in the hydrotherapy group.

The hydrotherapy group fared significantly better than the control group in terms of distance walked, the physical component of the SF-12 quality-of-life scale, and increased left quadriceps strength only at follow-up.

"The intensity, volume, and frequency of the exercise interventions was much higher than the American Geriatrics Society recommendations for strength training in patients with OA," the authors write. "The results of the current study support the prescription of higher intensity exercise for patients, even for those with severe OA who are awaiting a joint replacement."

Study limitations include a sample not necessarily representative of the general OA population, failure to control changes in drug use over the study period, and heterogeneity of the sample and the smaller-than-expected effect size, reducing the power needed to detect a significant change in self-reported measures.

Although both the gym and hydrotherapy interventions provided positive functional outcomes, the authors suggest that hydrotherapy may be more suitable for aerobic conditioning and that gym-based exercise may be more suitable for strengthening.

"Hydrotherapy provides the optimal environment for patients with OA to exercise aerobically, and at higher intensities than would be possible on land, owing to the reduction of joint loading," the authors write. "Patients with severe OA who find it painful to weight bear for extended periods may find that water provides the appropriate environment in which they can exercise at intensities that may confer significant health benefits.... Further research into hydrotherapy should investigate the long term effects of this form of exercise in patients with OA, and should also aim at measuring the effect of hydrotherapy on cardiovascular fitness."

Ann Rheum Dis. 2003;62:1162-1167

Clinical Context

According to a prospective study by Wyatt and colleagues published in the August 2001 issue of the Journal of Strength and Conditioning Research, 80% of adults older than 45 years have OA in at least one joint. Another study, by McAlindon and colleagues, evaluated different risk factors for functional disability associated with this common condition. Their research, published in the April 1993 issue of Annals of the Rheumatic Diseases, demonstrated that among 159 subjects with OA of the knee, quadriceps strength, knee pain, and age were associated with higher risk of disability. However, the severity of OA as determined by the knee radiograph did not correlate with rates of disability.

Given that variables such as quadriceps strength can limit OA patients' ability to accomplish activities of daily living, exercise rehabilitation is a priority for these individuals. The Wyatt study examined whether aquatic exercise programs might afford some advantage compared with land-based programs for OA, randomizing 46 adults to one of two 6-week exercise programs. At the end of the trial, subjects in the aquatic-based group reported less knee pain than their land-based counterparts, but knee range of motion, thigh girth, and one-mile walk time were similar between the two groups.

To further examine the benefits of hydrotherapy for patients with OA of both the hip and knee, Foley and colleagues conducted the current randomized, single-blinded trial.

Study Highlights

  • Study subjects were older than 50 years and had established OA of the hip, knee, or both. Exclusion criteria consisted of recent physiotherapy or planned joint replacement within the following 12 weeks.
  • Interventions included three 30-minute water- or gym-based exercise sessions per week for 6 weeks. The hydrotherapy program focused on resistance from the water to build strength, while the gym-based group underwent weight resistance training. Study participants were randomized to one of these exercise groups or to a control group.
  • An investigator blinded to the subject's study allocation evaluated pain, function, disability, perceived quality of life, and activities of daily living at baseline and again at 6 weeks. Isometric quadriceps strength was also measured.
  • 105 participants underwent randomization, and the mean age of participants was 70.9 years. The study population was nearly equally divided between men and women. Baseline characteristics among the 3 groups were similar, except that pain scores were slightly higher in the hydrotherapy group.
  • Walking speed increased in both active treatment groups compared with the control group, but there was no difference between the hydrotherapy and gym-based groups.
  • The gym-based group had significant improvement in quadriceps strength in both legs compared with baseline data, but the hydrotherapy group was noted to have improvement in the left quadriceps only. The gym-based group demonstrated stronger right quadriceps at 6 weeks than the hydrotherapy group.
  • The hydrotherapy group had reduced pain scores at study termination compared with baseline, but the gym-based and control groups did not.
  • The gym-based group scored higher on 2 elements of satisfaction of arthritis treatment than baseline, while the hydrotherapy group scored higher in the physical component of the quality-of-life score.
  • The mental outlook score improved in the gym-based group compared with baseline, but this was not true in the hydrotherapy group.
  • Physical function and stiffness scores were similar at baseline and at 6 weeks in all groups.
  • Increases and decreases of drugs used to treat OA cancelled each other out during the study period so that there was no difference between overall drug use at study initiation and at termination.
  • The authors suggest that patients with OA should use gym-based exercise to improve strength while training with hydrotherapy to improve OA pain as well as aerobic capacity. However, cardiovascular endurance was not measured in this study.

Pearls for Practice

  • Disability associated with knee OA can be predicted by certain patient factors.
  • Both hydrotherapy and a gym-based exercise program can improve certain parameters of care for patients with OA.

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