Hydrotherapy for Arthritis

By Marissa Blum, MD, and Sharon L. Kolasinski, MD; Dr. Blum is a rheumatology fellow in the Division of Rheumatology at the University of Pennsylvania School of Medicine; she reports no financial relationship relevant to this field of study. Dr. Kolasinski is Associate Professor of Clinical Medicine; Chief of the Clinical Service; and Program Director of the Rheumatology Fellowship Program in the Division of Rheumatology at the University of Pennsylvania School of Medicine; she reports no financial relationship relevant to this field of study.

Arthritis is a very common affliction, affecting as many as 48% of Americans over the age of 65.1 Chronic pain, decreased strength, and impaired mobility contribute to arthritis-related disability.2 No curative therapies are known yet and, therefore, treatment focuses on management of symptoms and reduction of disability. Options for treatment of pain include supportive therapies, such as non-steroidal anti-inflammatory medications, topical agents, gym- and home-based exercises, and intra-articular corticosteroid and hyaluronic acid injections. Ultimately, patients may require total joint arthroplasty.

Exercise therapy in arthritis patients has been demonstrated to improve pain, physical function, and self-reported disability.3 Hydrotherapy, or water-based exercise therapy, may provide another viable option for improving pain, mobility, and quality of life in patients with arthritis, and may be associated with high patient adherence to therapy. Several studies have attempted to examine the place of hydrotherapy in the management of patients with osteoarthritis or rheumatoid arthritis.


Hydrotherapy is based on an ancient modality called balneotherapy or bath therapy.4 Balneotherapy has classically been used to reference bathing in thermal or mineral waters, and today has been equated with spa therapy. Therapeutic baths were used in Roman times to treat various disorders, including painful musculoskeletal complaints, as well as to provide a forum for social interaction. Following the decline of the Roman Empire, spa therapy fell out of vogue, being considered "unmanly and devigorating" by some authors.5 However, by the 16th century, spa therapy was rediscovered and has been used continuously since then to treat a host of conditions.5 Hydrotherapy is a modern derivation of balneotherapy that involves exercise in warm water under the supervision of a physiotherapist.

Mechanism of action

Hydrotherapy has multiple potential mechanisms of action stemming from the effects of water and warmth on joints and soft tissues. On a biochemical level, little is known about the effects of "taking the waters." An almost two decade-old reference suggests that water immersion may alter circulating serum opioid peptide levels.6 On a more macroscopic level, benefits include pain relief and promotion of muscle relaxation that may be mediated by a number of factors. Joint swelling may be improved, since it has been shown that the size of edematous joints can be reduced following water immersion.7 Further, by decreasing the gravitational forces on joints, hydrotherapy reduces loading on damaged arthritic joints. On the other hand, hydrostatic pressure may shift blood volume from the lower extremities toward the core of the body, resulting in diuresis, natriuresis, and inhibition of the sympathetic nervous system.8,9,10 Water therapy may help to increase oxygen delivery to the tissues by improving venous and lymphatic return and, thus, increase perfusion of muscle and periarticular structures.11,12 The warmth that accompanies hydrotherapy may further add to its ability to relax muscles and increase circulation to symptomatic areas. Finally, the pleasure of the experience of water immersion may also have a significant effect on improving feelings of health and well-being.

Clinical Studies

Although a number of studies have evaluated hydrotherapy in arthritis patients, few are designed well enough to make definitive statements about the place of hydrotherapy in the management of arthritis. The Cochrane Collaboration has published a protocol for review of this topic to be completed soon.13 However, several recent reports provide support for some role for hydrotherapy.

Hall and colleagues used a randomized, controlled design to study the effects of hydrotherapy compared to land exercise, progressive relaxation, or water immersion.14 This study is of note because of the extensive evaluation methods employed and the relatively large sample size. Hall et al evaluated a group of patients with chronic, active rheumatoid arthritis (RA) on stable, though varied, drug regimens. One hundred forty-eight participants entered the trial, and 139 completed it 4 weeks later. All interventions took place at the Royal National Hospital for Rheumatic Diseases in Bath, UK. Patients were randomized to attend two 30-minute sessions twice a week in all four intervention groups. Hydrotherapy consisted of warm water immersion and exercise designed to increase range of motion and strength in upper and lower extremities. Land exercise consisted of similar exercises performed on land. The progressive relaxation group performed mental imagery tasks as directed by a physiotherapist reading from a standard script in a quiet, darkened room while seated on comfortable mats. The water immersion group relaxed in the pool on weighted chairs with legs dependent immersed in warm water to the suprasternal notch with legs dependent. Assessments of physical functioning included the Ritchie articular index of tender joints, minutes of morning stiffness, grip strength measured by digital hand held monitor, range of motion measured by goniometer, and C-reactive protein (CRP) levels. Pain was assessed by the McGill Pain Questionnaire (MPQ) and The Beliefs in Pain Control Questionnaire (BPCQ). Health status was assessed by the Arthritis Impact Measurement Scales 2 (AIMS2). All assessments were performed at study start and finish, as well as at a 3-month follow-up.

Hall et al found that, regardless of the intervention group, all patients showed significant improvement in joint tenderness by the Ritchie articular index between the start (21.2 ± 9.7) and the end of the study (17.3 ± 9.4, P = 0.002). However, the hydrotherapy group had the greatest improvement (21.3 ± 10.6 to 15.5 ± 9.4, P = 0.03), with a mean decrease of 27% in joint tenderness. On the other hand, only those in the land exercise group maintained their improvement in joint tenderness at follow-up 3 months later. Only women participating in hydrotherapy showed improvement (6.6° increase) in knee, but not other joint, range of motion. Among the pain outcomes, all patients had significant (P = 0.005) reductions in evaluative/affective pain scores measured by the MPQ from the start compared to the end of the intervention, although not maintained at the 3-month follow-up. Similarly, all subjects reported a significant (P = 0.049) reduction in the belief that pain was controlled by chance at the end of the intervention, but the change was not sustained at 3-month follow-up. In fact, this belief was strengthened in the immersion group at follow-up. Changes in health status seemed a bit more durable. All patients had a significant improvement (4.8%) in their physical capacity after treatment, as measured by the AIMS2, and this was maintained at follow-up. Overall, all subjects had significant improvements in mood and tension, which was also sustained at follow-up. Furthermore, those receiving hydrotherapy demonstrated the greatest improvement in affect (P = 0.03). Those in the progressive relaxation group had an increase in pain by about 12%, measured by the AIMS2, which persisted at follow-up. No changes were noted in grip strength, wrist range of motion, duration of morning stiffness, or CRP. One participant withdrew from the trial after having a myocardial infarction, but only 9 drop-outs occurred before the completion of the intervention (due to transportation difficulties, time constraints, and lack of interest).

A very recent study has revisited the question of hydrotherapy for rheumatoid arthritis. Eversden and colleagues evaluated hydrotherapy compared to land exercises in patients with stable rheumatoid arthritis.15 Subjects were on stable doses of disease-modifying anti-rheumatic drugs (DMARD) for 6 weeks prior to entering the trial. One hundred fifteen participants were randomized to receive 30-minute sessions of either hydrotherapy or land-based exercise for 6 weeks. Only 86 completed the trial (46 in the hydrotherapy group; 40 in the land exercise group). Primary outcome was the self-rated overall effect of treatment measured on the day of treatment completion, recorded on a 7-point scale, with 1 being "very much worse" to 7 being "very much better." Secondary outcomes were collected at study start, study completion, and 3 months post treatment. These included pain scores assessed with a 100 mm visual analog scale (VAS); physical function assessed with the health assessment questionnaire (HAQ); performance assessed by 10 meter walk time; and quality of life assessed through the EuroQol-5D valuation questionnaire (EQ-5D).

Eversden et al demonstrated a robust response in the primary outcome favoring hydrotherapy in RA. Significantly more patients in the hydrotherapy group (87%) felt "much better" or "very much better" (scoring 6 or 7 on the self rated overall effect of treatment scale) than patients in the land exercise group (47.5%, P < 0.001). This conclusion was supported even if all non-completers were considered non-responders, an analysis performed because of the greater drop-out rate in the land exercise group. However, there were no significant differences between the two intervention groups with regard to the secondary outcome measures. Ten meter walk times did improve after treatment and were maintained at follow-up in both groups. However, there was no significant change in pain by VAS, physical function by HAQ, or quality-of-life EQ-5D scores between the groups at the end of the intervention. Interestingly, there was a significant increase in pain and decrease in health status in both groups at the 3-month follow-up. In addition to the 26% drop-out rate, a weakness of this trial is that medication changes occurred commonly during the trial. By the time the 3-month follow-up occurred, 17.5% of the hydrotherapy subjects and 15.5% of the land exercise group had made changes in their DMARDs, and 7% in both groups had received corticosteroid joint injections.

Two additional studies from the osteoarthritis (OA) literature are worthy of mention. Pharmacologic treatment options for osteoarthritis, the most common form of arthritis, are more limited than that for rheumatoid arthritis. Thus, physical therapy and exercise interventions assume substantial importance as first line therapy in the osteoarthritis treatment armamentarium.

In 2003, Foley and colleagues from South Australia evaluated hydrotherapy against a gym-based resistance exercise program in 105 community dwelling individuals with radiographic evidence of hip and/or knee OA.16 Subjects were recruited from physiotherapy, orthopedic, and rheumatology practices, and were excluded if they had undergone physiotherapy or hydrotherapy within the last 6 weeks or were enrolled in community-based exercise classes. Participants were randomly assigned to one of three intervention groups: 3 water-based therapy sessions per week for 6 weeks; 3 gym-based therapy sessions per week for 6 weeks; or a control group who received telephone calls regarding their status every 2 weeks and were offered free exercise treatment at the end of the trial. Clinical response was assessed at study start and at study conclusion 6 weeks later. Outcome measures included quadriceps strength testing with a hydraulic leg extension machine, a 6-minute walk test and 4 self-reported outcome questionnaires: Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) measuring pain stiffness and physical function; the Adelaide Activities Profile assessing domestic chores, household maintenance, social activities, and service to others; the Short Form-12 Health Survey (SF-12) measuring physical and mental components of quality of life; and the Arthritis Self Efficacy Questionnaire measuring pain, function, symptoms, and satisfaction.

Quadriceps strength improved on the left side only in the hydrotherapy group (P = 0.01) while improving in both the left and right quadriceps in the gym group (P < 0.001), but not at all in the control group. Walking speed and distance improved significantly (P < 0.001) in the hydrotherapy and gym groups, but neither improved in the controls. WOMAC pain score significantly improved from baseline in the hydrotherapy group, although the change in pain was not significantly different between groups. No significant differences occurred for WOMAC function or stiffness, the Adelaide Activities Profile or the Arthritis Self Efficacy Questionnaire. At 6-week follow-up, the hydrotherapy group showed a significant improvement from baseline in the SF-12 physical component score (31.4 at baseline vs 37.1 at follow-up, P = 0.002), and this was significantly different from the controls. The gym group showed a significant improvement from baseline in the SF-12 mental component score, but this change did not differ significantly between groups. Only one subject in the hydrotherapy group changed their medication, while 9 gym and 11 control group subjects made changes. This study concluded that both forms of exercise were beneficial compared with no exercise intervention, and that hydrotherapy could result in improved walking speed and distance, but that neither are likely to result in improved strength. Foley et al suggested that improved ability to walk enhanced participants' sense of functional independence. They noted, however, that their results might not be generalizable since their recruits were highly motivated to participate in an exercise program.

A more recent Australian OA trial assessed hydrotherapy in comparison to tai chi, an intervention previously investigated and found to be of value in some patients with OA.17,18 Fransen and colleagues evaluated the effects of a hydrotherapy program in a randomized, controlled trial involving 152 participants with symptomatic osteoarthritis of the knees or hips.19 Participants were randomized to one of three groups: a hydrotherapy group where specific pool-based exercises were performed twice weekly for 1 hour; a Tai Chi group where specific exercises were performed twice weekly for 1 hour; or a waiting list control group. The primary outcome measures were pain and physical function scores using the (WOMAC), with higher scores indicating greater pain or physical disability. Secondary outcome measures included SF-12, the Depression, Anxiety, and Stress Scale (DASS21), patient global assessments, and physical performance tests (the Up and Go test, 50-foot walk time, and stair climb). Assessments were made at the study start, study end at 12 weeks, and at follow-up at 24 weeks.

Both exercise groups improved in at least some of the outcome parameters. At 12 weeks, moderate but significant improvements in WOMAC physical function were seen in both groups compared to controls. Only the hydrotherapy group experienced significant improvement in pain level, but treatment effects were small. Among the secondary outcomes, the hydrotherapy group made significant improvements in the SF-12, the DASS21, and all three physical performance tests. In terms of global assessment, 67% of the hydrotherapy group, 46% of the Tai Chi group, and 15% of controls reported that their signal hip or knee joint was "better" or "much better" compared with 3 months earlier. At the 6-month follow-up, 66% of the hydrotherapy 12-week responders and 58% of the tai chi 12-week responders were still treatment responders. A surprisingly high 11 participants were hospitalized for unrelated problems during the trial, and one in each exercise group withdrew due to exacerbation of low back pain.


Hydrotherapy has the potential to positively affect the pain level and functional status of patients with arthritis. Well-designed, relatively large trials of patients with RA and OA suggest that hydrotherapy can meaningfully and reproducibly contribute to pain management and improvement in function, as well as contribute to psychological well being. In comparison with other exercise techniques, hydrotherapy may offer benefits that are particular to arthritis patients due to the buoyant environment and reduced stress to joints or other factors. However, hydrotherapy is not likely to offer the same benefits as land-based exercise in terms of increases in strength. Other observations have suggested that hydrotherapy may be associated with higher compliance rates than other forms of exercise, an important consideration in arthritis patients with life-long disease.20,21


Hydrotherapy should be strongly considered when developing a treatment plan for people with arthritis. Hydrotherapy can improve pain and quality of life in patients with rheumatoid arthritis and osteoarthritis. It also provides a social environment for patients to come together while exercising and working to improve joint pain and mobility. Hydrotherapy is an important component of the comprehensive management of arthritis, and provides an evidence-based option for symptom control.


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