Aquatic Therapy Helps Healing After Knee and Hip Replacement

Date: March 1, 2012      Publication: Daily Health News      Source: Bruce Becker      Print:

You may have heard that aquatic therapy—exercising in a warm pool—is helpful for those who have undergone knee or hip replacements, but new research shows that exactly how soon the therapy is started after surgery can make a difference…and that for best results, knee patients should not follow the same schedule as hip patients! These surgeries are so invasive—and the stakes for the patients are so high—that I decided to call aquatic therapy expert Bruce Becker, MD, a specialist in physical medicine and rehabilitation and director of the National Aquatic & Sports Medicine Institute at Washington State University in Pullman, to discuss the new findings.


The study, done in Germany, involved 465 men and women (average age 58) who were scheduled to have knee or hip replacement. The goal of the study was to evaluate whether starting aquatic therapy earlier than the usual German starting point (on the 14th day after surgery) helped, hurt or made no difference. (In the US, there is no standard starting point.) Some knee and hip patients were assigned to begin pool-based therapy the sixth day after their surgery, while others were told to begin on the 14th day. All had three weekly, 30-minute supervised physical therapy sessions in a pool for up to five weeks post-op. Since most post-op pain relief and improvement in joint function tends to take place after three months, the subjects were asked a variety of questions (including ones about range of motion, stiffness and pain) at three months, six months, 12 months and 24 months post-op.

Who fared the best? Knee-replacement patients who started aquatic therapy on day six, compared to knee patients who started on day 14, reported better scores on almost every question asked during all four follow-up measurements (except for one question during one follow-up measurement—they reported more stiffness after 12 months). Hip-replacement patients, on the other hand, didn’t fare as well with an earlier start. Hip patients who started aquatic therapy on day six, compared to hip patients who started on day 14, reported worse scores on all the questions asked during all four follow-up measurements.


How come knee patients were better off starting early? The study author hypothesized that it may have to do with the amount of fluid buildup in the joint capsule, which causes some of the pain. And Dr. Becker agrees. For example, after surgery, the knee capsule is closed, so fluid can build up inside it, but the hip capsule is not closed, so no fluid can build up. The force of the water during aquatic therapy reduces the build up of fluid in the knee, but not in the hip.


The rub with aquatic therapy, though, said Dr. Becker, is that it’s underused here in the US. Dr. Becker is one of only a few thousand specialists who offers this kind of therapy. One reason is that warm-water therapy pools are expensive to staff and maintain. He also mentioned that there’s concern among some doctors about the potential for a recent surgical wound to become infected in a pool—especially since moisture can invite infection even after leaving a pool—but Dr. Becker said that today’s waterproof wound dressings are quite protective.

Bottom line: If you’re interested in trying aquatic therapy in the US after a knee or hip replacement, ask your surgeon about it, but know that it may take some work finding a supportive surgeon who is willing to write a prescription and help you find a rehab center with the right kind of pool. You can find an aquatic therapist and rehab pool near you by clicking on “Findpool” at, a site run by Aquatic Resources Network. And bring your surgeon this article to show him that the time you start the therapy could make an impact on how well you heal.

Source: Bruce Becker, MD, clinical professor at University of Washington School of Medicine, Seattle, adjunct research professor and director of the National Aquatics & Sports Medicine Institute at Washington State University, Pullman.