Aquatic Therapy and Total Knee Replacement: A Marriage Made in Therapy Heaven (Part 2)

Read Part 1 of this column at


Medicare paid approximately $3.2 billion in 2000 for hip and knee joint replacements. Total knee arthroplasty is one of the most common orthopedic procedures performed. 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, 2

Total knee replacement (TKR) is the most common surgical procedure used to treat a patient with an arthritic knee. Most patients who undergo total knee replacement are aged 60 to 80, but orthopedic surgeons evaluate patients individually. Recommendations for surgery are based on a patient's pain and disability, not age.

So 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.


Patient Is on a Weight-Bearing Restriction

Patients who are prohibited from weight-bearing on land are at risk for muscle atrophy, deconditioning, pneumonia, bone loss and a host of other ailments. In post-operative situations, the risks are even greater. Adhesions form quickly when a patient limits movement from pain or fear; this can result in the need to mobilize a joint, perform manipulation under anesthesia or even schedule a second surgery.

Even short term immobility can lead to a post-operative embolus forming in the leg. Infection risk can be multiplied when a patient is unable to easily perform dressing changes or ambulate to the bathroom for cleaning. Even incomplete restrictions, such as "weight bearing as tolerated" can result in a significant decline in function in a short period of time.

Clinicians with access to a therapy pool can bring a powerful option to the therapy table. In the pool, weight bearing may be reduced - from 0 percent to 100 percent total body weight simply by increasing the amount of the body submerged. In many situations, a pool patient can actually be allowed to ambulate in a near-normal fashion - without crutches or walker - during the entirety of their weight-bearing restriction.3,4


Patient is Unable to Support Weight Due to Obesity, Weakness or Other Factors

On land, patients are subject to the unrelenting downward pull of gravity. Their mass, under gravity's pull, results in a weight which they must struggle against in order to perform a simple task such as standing up from a chair. In the water, though mass remains the same, their weight is offset by buoyant forces and it becomes possible to perform a transfer (or walk) with less assistance.

For example, the severely overweight patient can be difficult to treat on land because of concerns about safety. In water, the bariatric patient no longer weighs dramatically more than his typical counterpart. Adipose tissue has a relative density less than water, and thus creates a counterbalancing upthrust to gravity's pull. It becomes possible to perform gait, balance and other tasks without the fear of the patient hurting himself or the therapist.

This can also be true with patients with post-surgical weakness. When working with this patient on land, the therapist is constantly fearful of a fall. Because of this anxiety, the therapist will often use a strong, protective hold on a gait belt and may automatically make balance adjustments for the patient in order to prevent catastrophic consequences. This robs the patient of the opportunity to experience near falls and thus steals from him the ability to learn balance reactions natural consequences of a loss of balance are not catastrophic. Patients can experiment and take chances in ways which would be unthinkable on land.5


Patient has Abnormal Gait Pattern or Uses an Assistive Device

Post-operative rehab of the lower quadrants is often complicated by the fact that patients can develop long-lasting abnormal gait patterns when they rely heavily on walkers or canes. How does this happen? Often it is a simple unresolved weakness. Other times, it comes about in a more insidious manner.

A patient who can support a portion of his weight by leaning forward onto a walker and hopping through the stance phase of gait may feel that this represents progress. It becomes a race to "get back on my feet" and many patients do not realize that their post-operative gait abnormalities are becoming habitual.

By immersing a patient in water, the therapist allows a patient the satisfaction of ambulating quickly without need for a walker or cane; this can provide a glimpse into the not-so-distant future. "What happens in the pool today will happen on land in a few weeks" can become the rallying cry that prevents a patient from trying to do too much immediately post-op.


Patient Is in Pain

Patients in pain often resist movement. Instead of fighting this, the wise therapist may choose to take the session into the pool. The warm buoyant environment can be harnessed to create a pain-reducing effect.

Buoyancy alone will create a decrease in weight bearing through joints, a decrease in joint stress, a decrease in splinting or guarding of antigravity muscles, and an increase in the patient's ability to move in opposition to gravity's forces.

The thermal properties of water can also help reduce pain. Although dependent on the population using the facility, therapeutic pools are generally heated to between 88 to 96° Fahrenheit. Immersion in water warmer than the skin will result in a rise in superficial tissue temperature which creates a palliative effect like that experienced during the therapeutic use of moist heat.

Therapists cannot adequately access the patient's body on land. On land, it can be difficult to position a patient comfortably and still have easy access to the patient's body. The water can provide the therapist with an invisible plinth which allows the therapists hands to "pass through" the table and have full access to the patient's body for stretching, joint mobilizations and other manual therapy.5


Patient Has Lower-Extremity Swelling

During immersion, the human body is subject to a phenomenon known as hydrostatic pressure. This pressure acts on the body automatically, even in the absence of movement or exercise. Because the external pressure from the water's pressure exceeds the internal pressure present in the patient's venous and lymphatic vessels, the water's pressure serves to squeeze the vessels into pushing fluid from an area of greater pressure (more distal) to the area of lesser pressure (more proximal).

The end result is a shift in hemodynamic flow to the chest and abdomen and a reduction in blood pooling and edema in the legs and feet.6 Less edema in the knee means less pain, greater ROM and even a stronger muscular contraction. Truly, it's a win-win scenario.

The water offers a unique therapeutic environment that can be harnessed by a skilled provider to permit activities unachievable on land. This environment is created because of the unique hydrodynamic and thermal properties of water. It is often both difficult and clinically impractical to achieve a similar environment on land; thus, a strong case can be made for performing patient care for this population in water.



1. Kane, R., Saleh, K., et al. (2003). Total Knee Replacement. Evidence Reports/Technology Assessments, No. 86. Rockville (MD): Agency for Healthcare Research and Quality (US).

2. Jordan, K., et al. (2003). EULAR recommendations 2003: An evidence-based approach to the management of knee osteoarthritis-Report of a task force of the Standing Committee for International Clinical Studies Including Therapeutic Trials (ESCISIT). Annals of Rheumatic Disorders, 62, 1145-1155.

3. Harrison, R., & Bulstrode, S. (1987). Percentage weight bearing during partial immersion in the hydrotherapy pool. Physiotherapy Practice, 3, 60-63.

4. Harrison, R., Hillma, M., & Bulstrode, S. (1992). Loading of the lower limb when walking partially immersed: Implications for clinical practice. Physiotherapy, 78(3), 164-166.

5. Salzman, A., Becker, B. (2010). Justifiable Aquatic Therapy Strategies for the Total Hip & Knee Replacement Client. Aquatic Therapy University; Minneapolis, MN; April 2010. Manual available at 

6. Becker, B. (2009). Aquatic therapy: Scientific foundations and clinical rehabilitation applications. PMR, 1(9), 859-872.

7. Honda, T., & Kamioka, H. (2012). Curative and health enhancement effects of aquatic exercise: Evidence based on interventional studies. Open Access Journal of Sports Medicine, 3, 27-34.

Andrea Salzman is creator of the Aquatic Resources Network (, the single largest clearinghouse of aquatic therapy and fitness information online. At the ARN Online Command Center, more than 8,000 aquatic-specific articles and downloads are available free for the public. Individuals seeking advanced competency in aquatic therapy can now pursue a tiered curriculum of training through Aquatic Therapy University ( In 2010, Salzman teamed with 12 PTs/OTs/SLPs/MDs and PhDs to develop this first-in-the-industry Aquatic Therapy Credentialing Path, an 84-hour progression of training for the therapist seeking advanced clinical expertise. Drop Andrea a note at (She gets out of the pool at 5:00!) Copyright 2012. All rights reserved.




Water Wisdom Archives


Email: *

Email, first name, comment and security code are required fields; all other fields are optional. With the exception of email, any information you provide will be displayed with your comment.

First * Last
Title Field Facility
City State

Comments: *
To prevent comment spam, please type the code you see below into the code field before submitting your comment. If you cannot read the numbers in the below image, reload the page to generate a new one.

Enter the security code below: *

Fields marked with an * are required.

View the Latest from ADVANCE


Search Jobs


Back to Top

© 2017 Merion Matters

660 American Avenue Suite 300, King of Prussia PA 19406