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Aquatic Therapy and Total Knee Replacement

Updated: Jun 21

Byline: Andrea Salzman, MS, PT

Your patient Mrs. K presents with osteoarthritis in both knees. She is in constant pain and her morbid obesity makes it difficult for her to exercise. She is a future candidate for bilateral total knees and is being seen for a course of conservative management to see if the surgery can be delayed 1-2 years. She has a loss of joint integrity, restricted ROM and loss of functional strength. She has morning stiffness and pain in her knees and low back and trouble sleeping at night. She is reliant on an assistive device which alters her postural relationship with the environment. You immediately think "water." Find out if you made the right choice.

Making the Case for Aquatic Therapy

Therapists have many skills which they bring to the therapeutic table. By offering both land and water, a therapist can amplify the strengths - or minimize the weaknesses of - either environment. There are many compelling reasons for choosing to treat a patient in water, not the least of which may be patient preference.

Sadly, one of the trends currently seen in the reimbursement world is a tendency for the payer to play therapist and decide when or even if water-based intervention is appropriate. This has progressed in some circles to the point where a payer will demand that a patient first fail in traditional land-based therapy before permitting a bout of aquatic treatment. Or, that water-based therapy must be clearly superior (and not just equally effective) to its land-based counterpart.

Total knee replacement (TKR) is the most common surgical procedure used to treat a patient with an arthritic knee. Medicare paid approximately $3.2 billion in 2000 for hip and knee joint replacements. Because these procedures are elective and so expensive and because the prevalence of arthritis is expected to grow substantially as the population ages, these procedures are likely to come under increasing scrutiny. [1]

Evidence-Based Claims

Take, for example, a California Independent Medical Review Board decision to uphold the payer's denial of aquatic therapy for a TKA patient (chart). A Review Board was brought in to determine if the payer had inappropriately denied aquatic therapy for their client. In this situation, a 54-year-old female received aquatic-based physical therapy (PT) from a noncontracted provider for the treatment of her knee status post total knee arthroplasty. The payer denied the claim and she filed an appeal.

The physician reviewer found that although aquatic therapy is "certainly a choice of modality for treatment, there is no proven benefit over land based PT" in the treatment of osteoarthritis of the knee/hip. In a foray into the hypothetical, the same physician states that, though it was true that the patient had made gains in ROM with aquatic PT, those "gains may have been made had the patient continued landbased therapy."

To bolster this allegation, he cited several researchers (Wyatt et al; Bartels et al, and others) to make the claim that though aquatic exercise is effective, it has not been shown to be superior to land-based exercise for this population.

The thinking clinician's first question should be: so what? If aquatic-based intervention and land-based intervention both produce equally effective results, shouldn't then the decision to choose one environment over another fall to the licensed professional and his or her client?

[Note: Certainly, if the payer was making the argument that it should not be forced to pay for a service provided outside the network when an equally effective service was available internally, that argument has merit, but that was not the argument made.]

Secondly, the researcher should be pointed to: Gibson, A. J., & Shields, N. (2015). Effects of aquatic therapy and land-based therapy versus land-based therapy alone on range of motion, edema, and function after hip or knee replacement: a systematic review and meta-analysis. Physiotherapy Canada, 67(2), 133-141.

More Research Support

In the past 10 years, the tables have turned somewhat. There have been multiple studies published which do show an advantage to aquatic over land-based interventions. 4-7 For example, according to a new study published in the Archives of Physical Medicine and Rehabilitation, beginning aquatic therapy just 6 days after TKA may lead to improved results.

"This multicenter study demonstrates that the timing of physiotherapy measures, such as aquatic therapy, has clinically relevant effects after TKA," says lead investigator Thoralf R. Liebs, MD, of the Department of Orthopaedic Surgery, University of Schleswig-Holstein Medical Center, Kiel, Germany. "Ours is one of the few studies that demonstrates a clinically important effect on the health-related quality of life after TKA by a factor that can be influenced by the healthcare professional. The intervention is simple to administer, and requires limited extra input from the healthcare professional." [4]

Even in the face of such evidence, aquatic clinicians continue to be required to show "special justification" by payers. Such a phenomenon can hamstring the decision-making matrix of the skilled therapist and subtly compel clinicians to choose easy, instead of choosing best.

When a patient with a severely degenerated knee - or a post-operative one - walks in the front door, the master clinician should immediately begin an assessment: land or water? That same wise clinician should intuitively understand that are certain reasons to choose to aquatic therapy which are more compelling than others. Some of these include:

  • The patient is on a weight-bearing restriction;

  • The patient is unable to support his weight to initiate ambulation due to obesity, weakness or other factors;

  • The patient has an abnormal gait pattern or makes excessive use of an assistive device;

  • The patient is in too much pain to treat on land;

  • The therapist cannot adequately access the patient's body on land;

  • The patient has lower-extremity edema. [2]

(Note: For a more detailed discussion of each of these factors-including supporting evidence-look for Part 2 of this series.)

Clinicians who have access to both land and water can offer their patients a special opportunity: both sides of the therapeutic coin. However, it is important to remember that the current insurance climate requires the wise therapist be able to justify his choice of water over land. something that recent publications continue to make even easier for the aquatic clinician. [4-7]


1. Kane, R., Saleh, K., et al. (2003). Total Knee Replacement: Summary. AHRQ Evidence Report Summaries.

2. Salzman, A., Becker, B. (2020). Justifiable Aquatic Therapy Strategies for the Total Hip & Knee Replacement Client. Aquatic Therapy University; Minneapolis, MN; April 2020. Manual available at

3. Salzman, A. (2021). Evidence-based aquatic therapy. Aquatic Therapy University; Minneapolis, MN; 2021. Manual available at

4. Lee, C. H., & Kim, I. H. (2021). Aquatic exercise and land exercise treatments after total knee replacement arthroplasty in elderly women: a comparative study. Medicina, 57(6), 589.

5. Kim, S., Hsu, F. C., Groban, L., Williamson, J., & Messier, S. (2021). A pilot study of aquatic prehabilitation in adults with knee osteoarthritis undergoing total knee arthroplasty–short term outcome. BMC Musculoskeletal Disorders, 22, 1-11.

6. Khruakhorn, S., & Chiwarakranon, S. (2021). Effects of hydrotherapy and land-based exercise on mobility and quality of life in patients with knee osteoarthritis: a randomized control trial. Journal of physical therapy science, 33(4), 375-383.

7. Alonso-Rodríguez, A. M., Sánchez-Herrero, H., Nunes-Hernández, S., Criado-Fernández, B., González-López, S., & Solís-Muñoz, M. (2021, August). Efficacy of hydrotherapy versus gym treatment in primary total knee prosthesis due to osteoarthritis: a randomized controlled trial. In Anales del sistema sanitario de Navarra (Vol. 44, No. 2, pp. 225-241).

Online Resources

Aquatic Therapy University - Post graduate studies in aquatic therapy;

Aquatic Physiotherapy Evidence-Based Guide; of Aquatic Exercise and Balneotherapy: A Summary of Systematic Reviews Based on Randomized Controlled Trials of Water Immersion Therapies;

Evidence-Based Systemic Review of the Effectiveness of Hydrotherapy;

Bruce Becker's Aquatic Therapy: Scientific Foundations;

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