If you are planning a total knee replacement, it is reasonable to ask whether you should start physical therapy before surgery rather than waiting until afterward.
The short answer is: prehab can be useful, especially for building strength, improving movement, practicing the skills you will need after surgery, and identifying problems that could make recovery harder. But it is not a magic shortcut, and the evidence does not show that every patient needs a long preoperative therapy program.
For some patients, a few weeks of focused preparation may make the early recovery period easier. For others, especially people with severe arthritis who are already appropriately indicated for knee replacement, forcing months of additional therapy may simply prolong pain without changing the need for surgery.
That distinction matters.
At Pacific Bone & Joint, I think of prehab as preparation for surgery, not as a hurdle a patient must clear before being allowed to have surgery.
What is prehab before knee replacement?
“Prehab” means rehabilitation performed before an operation. Before total knee replacement, this usually involves a structured physical therapy or home exercise program designed to improve the factors that can still be changed before surgery.
Depending on the patient, those factors may include:
- Quadriceps and hip strength
- Knee extension and flexion
- Walking tolerance
- Balance and fall risk
- Ability to use a walker or cane safely
- Stair technique
- Confidence with transfers, such as getting in and out of a chair or bed
- Cardiovascular conditioning
- Understanding the postoperative exercise plan
- Home setup and equipment needs
The goal is not to make an arthritic knee normal before surgery. If the joint has advanced cartilage loss and the patient has already failed appropriate nonsurgical treatment, strengthening exercises do not reverse the arthritis.
The goal is to enter surgery with the best function and preparation reasonably possible.
Does physical therapy before knee replacement actually work?
The evidence is encouraging in some areas, but it is not as simple as saying that every patient who does prehab will recover faster.
A 2025 overview of systematic reviews and meta-analyses in the Journal of Orthopaedic & Sports Physical Therapy evaluated structured prehabilitation before total hip and knee arthroplasty. The overall literature suggested that prehabilitation may improve selected early outcomes, but the studies varied substantially in the type, duration, intensity, and supervision of exercise programs. Read the PubMed summary.
A 2022 JOSPT systematic review and meta-analysis of 16 trials involving 968 patients found low- to very-low-certainty evidence that exercise-based prehab improved knee function before surgery and during the first three months after total knee arthroplasty. The review did not find a meaningful long-term difference at six to twelve months. Read the systematic review.
More recently, a 2026 systematic review of 11 randomized controlled trials found small-to-moderate advantages for some early pain, functional, and performance outcomes. Programs emphasizing progressive strengthening and balance or proprioceptive work tended to perform better, while effects on range of motion and hospital length of stay were inconsistent. Durable differences at six to twelve months were uncommon. Read the 2026 review.
So the practical interpretation is:
Prehab may help the early phase of recovery, but it should not be sold as a guarantee of a dramatically better final result.
Why strength before surgery matters
One of the most important issues before knee replacement is quadriceps weakness.
Arthritis causes pain, swelling, altered walking, and reduced activity. Over time, the thigh muscle can become weaker. After knee replacement, the quadriceps temporarily becomes even less efficient because of pain, swelling, surgical trauma, and a phenomenon called arthrogenic muscle inhibition.
That is one reason patients sometimes describe the leg as feeling “heavy” or difficult to control in the first days after surgery.
A patient who enters surgery with better baseline strength may have more reserve during that early period. This does not mean the strongest patient automatically has an easy recovery, but it is one reason progressive strengthening is a major part of prehabilitation.
Useful exercises may include, when tolerated and individualized by a therapist:
- Sit-to-stand practice
- Supported squats or functional closed-chain strengthening
- Quadriceps strengthening
- Hip abductor and extensor strengthening
- Step training
- Stationary cycling or other low-impact conditioning
- Balance and single-leg control exercises when safe
The exact program should match the patient. Someone with severe pain, instability, poor balance, a major flexion contracture, or another medical limitation should not simply copy a generic online exercise routine.
Is range of motion before surgery important?
Yes, but with an important qualification.
A knee that cannot fully straighten before surgery may be more challenging to rehabilitate afterward. Significant stiffness can affect gait, transfers, and function. For that reason, prehab often includes work on knee extension, flexion, soft-tissue mobility, and swelling control.
But patients should not interpret this as a requirement to achieve a specific bending number before they can have knee replacement.
Some arthritic knees are mechanically stiff because of osteophytes, deformity, joint-space loss, scar tissue, or long-standing contracture. Aggressively forcing a painful knee can increase inflammation without meaningfully changing the underlying problem.
The aim is reasonable improvement without provoking a major flare.
Prehab is also practice for the first week after surgery
Physical therapy before surgery is not only about building muscle.
A good preoperative session can teach patients how to perform the practical tasks that become important immediately after surgery:
- How to use a walker safely
- How to get out of bed
- How to stand from a chair without twisting
- How to negotiate stairs
- How to position the leg for extension
- How to use ice and elevation appropriately
- How often to walk
- Which early exercises matter most
- How to recognize unsafe compensation patterns
Learning these skills before surgery can reduce the amount of new information a patient has to absorb while tired, sore, and taking postoperative medications.
That preparation is hard to measure in a research study, but it is clinically useful.
Who may benefit most from prehab?
Prehab may be particularly valuable when a patient has a modifiable limitation that is likely to affect early recovery.
Examples include:
- Marked leg weakness
- Poor balance or fall risk
- Difficulty using a walker or cane
- Significant gait dysfunction
- Low exercise tolerance
- Difficulty rising from a chair
- Limited knee extension
- Deconditioning after a period of inactivity
- Previous difficulty recovering from surgery
- Uncertainty about postoperative exercises or home safety
A 2025 systematic review specifically examined prehabilitation in patients considered at risk for poorer outcomes after total knee arthroplasty. The evidence was still limited and heterogeneous, which is important. The authors concluded that exercise-based and multidisciplinary prehabilitation remain promising but not definitively proven for every high-risk group. Read the review.
This is why individualized assessment matters more than simply prescribing the same “prehab package” to everyone.
When should physical therapy not delay knee replacement?
This may be the most important question in the entire discussion.
The American College of Rheumatology and the American Association of Hip and Knee Surgeons published guidance on the timing of elective hip and knee arthroplasty for patients with symptomatic, radiographically moderate-to-severe osteoarthritis who have already tried appropriate nonsurgical treatment.
For patients who are already appropriately indicated for joint replacement, the guideline conditionally recommends proceeding with surgery rather than delaying the operation solely to require another trial of physical therapy. The document specifically distinguishes that recommendation from prehabilitation intended to prepare a patient for surgery. Read the ACR/AAHKS timing guideline.
That is a useful distinction.
If a patient has severe bone-on-bone arthritis, substantial loss of function, persistent pain, and has already exhausted reasonable nonsurgical options, therapy does not need to become an arbitrary barrier to surgery.
On the other hand, if the patient has severe weakness, poor balance, is recovering from another medical problem, or is so deconditioned that postoperative mobility would be unsafe, a targeted period of physical therapy may be worth the delay.
How long should prehab last?
There is no universally proven “correct” duration.
Research studies have used widely different programs, from a few weeks to much longer periods, which is one reason the evidence is difficult to compare.
In practice, if surgery is already scheduled, even a relatively short window can be useful for:
- Establishing a baseline
- Teaching the postoperative routine
- Improving quadriceps activation
- Practicing assistive devices
- Working on extension
- Building confidence
- Addressing obvious balance or mobility problems
The key is consistency and specificity, not accumulating a certain number of therapy visits.
A patient who has excellent strength, good balance, full extension, and already exercises regularly may need less supervised prehab than someone who struggles to stand from a chair or walk one block.
What should a good knee replacement prehab program include?
A useful program should be more than a handout of exercises.
1. A baseline functional assessment
The therapist should understand how you currently walk, transfer, climb stairs, and move through daily life.
2. Strength training
The quadriceps are a major priority, but the hip muscles and the rest of the lower extremity matter too.
3. Knee motion
Particular attention is usually given to restoring or preserving full extension while maintaining comfortable flexion.
4. Balance and gait training
If you are unsteady before surgery, it is better to identify that problem before you are also dealing with postoperative pain and swelling.
5. Cardiovascular conditioning
Low-impact conditioning can help maintain general fitness when arthritis limits walking.
6. Postoperative education
Patients should know what the first several days are likely to involve, how often to walk, what exercises matter, and how to use assistive devices.
7. A realistic home program
The best exercise plan is not the most complicated one. It is the one a patient can perform safely and consistently.
Our PB&J Physical Therapy team provides in-house rehabilitation that can coordinate preoperative preparation with postoperative recovery when appropriate.
What prehab cannot do
Prehabilitation has limits.
It cannot:
- Regrow cartilage that has been lost from advanced osteoarthritis
- Correct a fixed bony deformity
- Guarantee that postoperative pain will be mild
- Eliminate postoperative swelling
- Prevent every complication
- Guarantee a particular range of motion
- Replace the need for surgery when the joint has reached the point that replacement is the appropriate treatment
Patients should be cautious about any program promising that prehab will make knee replacement “easy” or guarantee an unusually fast recovery.
Preparation helps. Biology still matters.
What about weight loss, nutrition, smoking, diabetes, and other optimization?
Those issues are related to preoperative optimization, but they are not identical to physical therapy.
A complete preparation plan may also address:
- Blood sugar control
- Smoking or nicotine use
- Nutrition and protein intake
- Anemia
- Sleep apnea
- Medication management
- Fall risk
- Home support
- Weight when it meaningfully affects surgical risk
These factors should be addressed individually. They should not become one-size-fits-all reasons to indefinitely postpone surgery.
The purpose of optimization is to reduce avoidable risk and improve readiness, not to create an impossible checklist.
What happens after surgery?
Prehab does not replace postoperative physical therapy.
After knee replacement, rehabilitation shifts toward:
- Safe walking
- Swelling control
- Restoring full extension
- Progressive knee flexion
- Quadriceps activation
- Strength and endurance
- Balance
- Stair function
- Return to work and recreation
If you want a detailed timeline, our knee replacement recovery week-by-week guide explains what many patients can expect from the first 48 hours through the first several months.
The important point is continuity. A patient who learns the basic movement strategy before surgery can often begin the postoperative phase with fewer surprises.
Should everyone do formal prehab?
No.
Some patients may benefit from supervised physical therapy. Others may do well with one or two education sessions plus a structured home program. Patients who are already fit, strong, balanced, and familiar with exercise may need less preparation.
The right question is not:
“Does everyone need prehab?”
It is:
“What modifiable problem does this particular patient have before surgery, and can we improve it?”
That is the approach I find most useful.
Questions to ask before starting prehab
Before knee replacement, consider asking:
- Do I have a major strength deficit?
- Can I fully straighten my knee?
- Am I safe walking with a walker?
- Do I have balance problems?
- Which exercises should I prioritize?
- Which exercises are aggravating my arthritis without adding value?
- Do I need formal supervised therapy or can I use a home program?
- Is therapy being used to prepare me for surgery, or simply to delay a surgery I already need?
- What will change in my exercise plan immediately after surgery?
The bottom line
Prehab before knee replacement can be worthwhile, particularly when it targets weakness, stiffness, balance, poor walking mechanics, or uncertainty about the postoperative routine.
The best evidence suggests that preoperative physical therapy may improve some early recovery measures, while long-term differences are less certain. That makes sense clinically: prehab gives patients a better starting point, but the eventual result still depends on the surgery, biology, rehabilitation, health, and time.
Most importantly, prehab should be individualized. It should help a patient prepare for knee replacement, not become an automatic requirement that prolongs severe arthritis symptoms without a clear purpose.
If you are considering knee replacement in Hawai‘i and want to know whether preoperative physical therapy would meaningfully improve your readiness, Pacific Bone & Joint can evaluate your strength, motion, walking, and overall surgical plan and help determine what preparation makes sense for you.
Sources and further reading
- Keogh JAJ, Keng I, Dhillon DS, et al. The Effects of Structured Prehabilitation on Postoperative Outcomes Following Total Hip and Total Knee Arthroplasty: An Overview of Systematic Reviews and Meta-analyses of Randomized Controlled Trials. Journal of Orthopaedic & Sports Physical Therapy. 2025. PubMed
- Vervullens S, Meert L, Baert I, et al. Prehabilitation before total knee arthroplasty: A systematic review on the use and efficacy of stratified care. Annals of Physical and Rehabilitation Medicine. 2023. PubMed
- Moyer R, Ikert K, Long K, Marsh J. Prehabilitation Improves Knee Functioning Before and Within the First Year After Total Knee Arthroplasty: A Systematic Review With Meta-analysis. Journal of Orthopaedic & Sports Physical Therapy. 2022. PubMed
- Karimijashni M, Yoo S, Barnes K, et al. Prehabilitation in Patients at Risk of Poorer Outcomes Following Total Knee Arthroplasty: A Systematic Review. Journal of Arthroplasty. 2025. PubMed
- Efficacy of Pre-operative Physical Therapy on Total Knee Replacements: A Systematic Review of Randomized Controlled Trials. 2026. PubMed
- American College of Rheumatology and American Association of Hip and Knee Surgeons. Clinical Practice Guideline for the Optimal Timing of Elective Total Hip or Knee Arthroplasty. Guideline
