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Top 8 Reasons the Pool Rules for TKR (Quick: Go Tell their Surgeon the Science is IN!)

Eight research-backed reasons to add the pool to total knee replacement rehab, from pain and function to strength, mood and safety.

Published by Aquatic Therapy University4 min read

  • Orthopedic
  • Rheumatology
  • Mental Health
  • Chronic Pain
First published January 18, 2025 on atuseminars.com

Many total knee patients still go straight to land-based rehab. We think the research now makes a strong case for adding the pool, both before and after surgery.

Here are eight reasons, each tied to a study you can check and share with the surgeon.

Want to go deeper? Explore the Aquatic Therapy After Total Knee Replacement course →

A therapist supports a young man who holds a pool noodle in the water.
Aquatic resistance training can improve walking speed and stair climbing after knee replacement.

Who says the pool rules? SCIENCE says the pool rules! Science in the house!!

Top 8 Reasons Why Water Works for the TKR:

  1. Improved Functional Outcomes: Aquatic therapy has been shown to significantly improve functional outcomes, such as chair-stand performance and overall physical function, in patients undergoing TKR.[1]
  2. Pain Reduction: Aquatic therapy effectively reduces knee pain in patients with knee osteoarthritis, which can be beneficial for TKR patients both pre- and post-operatively.[2,3]
  3. Enhanced Mobility: Aquatic resistance training improves walking speed and stair ascending time, which are critical for post-TKR rehabilitation.[4]
  4. Improved Quality of Life: In a meta-analysis of six trials, hydrotherapy lowered pain and improved WOMAC scores at 1, 4 and 8 weeks.[5]
  1. Reduced Depression and Improved Cognition: Aquatic therapy has been shown to improve depression and cognitive function in elderly patients undergoing TKR, contributing to better overall mental health.[1]
  2. Safety and Tolerability: Aquatic therapy is well-tolerated and safe, with no serious adverse events reported, making it a suitable option for patients with knee osteoarthritis and those undergoing TKR.[3][5]
  3. Enhanced Muscle Strength and Power: Aquatic resistance training increases knee extensor and flexor power, as well as thigh muscle cross-sectional area, which are essential for recovery after TKR.[4]
  4. Sustained Benefits: The pain benefit of aquatic exercise lasted at least three months after treatment ended.[3]

Together, these points collectively highlight the multifaceted benefits of aquatic therapy for TKR patients, emphasizing improvements in pain, function, mobility, quality of life, mental health, and muscle strength.

Newer research

  • Timing matters. In a large trial comparing early with late aquatic therapy after joint replacement, early pool work showed a small benefit after knee replacement (not statistically significant) but no benefit after hip replacement.6
  • Compared with other rehab. A 2025 network meta-analysis of rehabilitation after knee replacement ranked hydrotherapy among the methods with good effects on WOMAC scores.7

Most of these trials are small. The pain benefit is the best supported; function gains are short-term.

Frequently asked questions

Does aquatic therapy reduce knee pain?

Yes. In people with knee osteoarthritis, aquatic therapy lowers knee pain, which can help both before and after TKR (Aquatic Therapy University, 2025).

Is aquatic therapy safe for knee osteoarthritis and TKR?

The studies reviewed here found it well tolerated, with no serious adverse events reported (Aquatic Therapy University, 2025).

How long do the benefits of aquatic therapy last?

Improvements in pain and physical function lasted at least three months after treatment ended (Aquatic Therapy University, 2025).

References

References cited in the original post

Numbers 1 to 5 match the citation numbers in the text.

  1. Randomized controlled trialKim S, Hsu FC, Groban L, Williamson J, Messier S. A pilot study of aquatic prehabilitation in adults with knee osteoarthritis undergoing total knee arthroplasty - short term outcome. BMC Musculoskelet Disord. 2021;22(1):388. doi:10.1186/s12891-021-04253-1. PubMed: 33902505.
  2. Randomized controlled trialRewald S, Lenssen AFT, Emans PJ, de Bie RA, van Breukelen G, Mesters I. Aquatic Cycling Improves Knee Pain and Physical Functioning in Patients With Knee Osteoarthritis: A Randomized Controlled Trial. Arch Phys Med Rehabil. 2020;101(8):1288-1295. doi:10.1016/j.apmr.2019.12.023. PubMed: 32169459.
  3. Systematic review and meta-analysisXu Z, Wang Y, Zhang Y, Lu Y, Wen Y. Efficacy and safety of aquatic exercise in knee osteoarthritis: A systematic review and meta-analysis of randomized controlled trials. Clin Rehabil. 2023;37(3):330-347. doi:10.1177/02692155221134240. PubMed: 36320162.
  4. Randomized controlled trialValtonen A, Pöyhönen T, Sipilä S, Heinonen A. Effects of aquatic resistance training on mobility limitation and lower-limb impairments after knee replacement. Arch Phys Med Rehabil. 2010;91(6):833-9. doi:10.1016/j.apmr.2010.03.002. PubMed: 20510971.
  5. Systematic review and meta-analysisLei C, Chen H, Zheng S, et al. The efficacy and safety of hydrotherapy in patients with knee osteoarthritis: a meta-analysis of randomized controlled trials. Int J Surg. 2024;110(3):1711-1722. doi:10.1097/JS9.0000000000000962. PubMed: 38051935.

Newer research

  1. Randomized controlled trialLiebs TR, Herzberg W, Rüther W, et al. Multicenter randomized controlled trial comparing early versus late aquatic therapy after total hip or knee arthroplasty. Arch Phys Med Rehabil. 2012;93(2):192-9. doi:10.1016/j.apmr.2011.09.011. PubMed: 22196125.
  2. Systematic reviewJin Z, Tang Y, Huang H, et al. Comparison of Therapeutic Effects of Different Rehabilitation Methods on Patients Undergoing Total Knee Arthroplasty: A Network Meta-Analysis of Randomized Controlled Trials. Orthop Surg. 2025;17(2):348-360. doi:10.1111/os.14332. PubMed: 39780331.

How to cite this article

First published January 18, 2025 on atuseminars.com · Last updated October 19, 2026 · Permanent URL: https://www.aquatictherapyuniversity.com/blog/top-8-reasons-the-pool-rules-for-tkr

How to cite

Aquatic Therapy University. (2025, January 18). Top 8 Reasons the Pool Rules for TKR (Quick: Go Tell their Surgeon the Science is IN!). Aquatic Therapy University Blog. ATU Educational Services, LLC. https://www.aquatictherapyuniversity.com/blog/top-8-reasons-the-pool-rules-for-tkr

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For education only; not a substitute for individual clinical judgment.