Want Dr. Calendine’s articles to stand out in your Google and AI search results? Add him as a preferred source (one tap).
Do you need physical therapy after knee replacement?
Yes. After a knee replacement, physical therapy is not optional, and everybody should go.
That surprises some patients, especially if a friend or family member had a hip replacement and never set foot in a therapy clinic. For most hip patients, walking is the exercise, and formal therapy is optional. I explain why in my article on hip replacement physical therapy. A knee is a different joint with a different job, and the recovery works differently.
“Patients ask me all the time whether they really need therapy. After a hip replacement, most people do not do any formal physical therapy. A knee replacement is very different. Knee replacement physical therapy is not optional, and everybody should go. The motion you work for in those first weeks is the motion you keep.”
Why is knee replacement physical therapy different from hip?
A hip gets most of its motion back simply by walking. A knee has to bend and straighten through a much bigger arc, and it has to do that while it is swollen, sore, and protective after surgery. Left alone, a swollen knee gets tight, and a tight knee is hard to bend.
Therapy is where that motion gets earned. Your therapist knows how hard to push a swollen, early knee, when to back off, and when you are ready for the next step. That judgment is hard to replace at home, especially in the first few weeks.
When does knee replacement physical therapy start?
It starts the day of surgery. Everyone gets up and walks the same day, and everyone practices stairs before going home, whether that is from the hospital or the surgery center. You bend and straighten the knee gently that first day, too.
Formal therapy starts within one to two days of surgery. I recommend going straight to an outpatient physical therapy clinic rather than having therapy at home, for reasons covered below.
Your walker or cane is there for balance, not because the knee cannot take weight. You can put your full weight on your new knee right away. When to move from one to the other is covered in my guide to the walker or cane.
How often and how long is physical therapy after knee replacement?
Most patients go about three times a week for roughly six weeks. Some need more, and some need less. The number of weeks is not the goal. The goal is a knee that bends and straightens well and a leg strong enough to walk without a limp.
Between sessions, you have homework, and it matters as much as the sessions. Your therapist sets your home program. Expect to do some level of exercise at least once a day, sometimes twice, and rarely three times. I always tell patients that the physical therapist is really there as your guide, but the real work happens on your own.
What does knee replacement physical therapy focus on?
Range of motion first, then strength. In the early weeks the priority is getting the knee to straighten fully and bend comfortably. Straightening deserves as much attention as bending: in some ways, a knee that gets fully straight matters more for how you walk than a deep bend. Two simple home stretches help. Rest your heel up on an ottoman and press gently down on the knee, or lie face down with the knee at the edge of the bed and let the lower leg hang. Once swelling is under control and the knee is bending and straightening well, your therapist adds progressive strength work, usually around four weeks. Most of the motion comes back during weeks two to six, and it keeps improving for months after that. My week-by-week range of motion guide walks through what to expect at each stage.
Milestones I check. I see knee patients at two weeks, again at four weeks if the knee is stiff, and everyone at six weeks. A bend of 90 degrees is the bare minimum by six weeks, and most knees are well past it. In my practice, if a knee has not reached 90 degrees on its own by about six weeks, that is when I consider a manipulation, a gentle bend of the knee done while you are asleep. Surgeons use different thresholds; this is mine.
Swelling control, the whole way through. A swollen knee is a tight knee. Ice with a cloth barrier between the cold and your skin, every time, and ice after your exercises and after therapy, when the knee swells the most. A large systematic review of 140 studies found that cold therapy during the first two weeks after knee replacement was consistently associated with less swelling.[1] A cold therapy machine makes icing easier to keep up with, but it is not required. The details are in how to ice after knee replacement.
Walking. Short, frequent walks keep the knee from stiffening. They count as part of the program.
“It is okay to start slow, almost insultingly slow, and then gradually build. In the first week or two I follow what I call the quiet knee protocol: we don’t overdo it until the swelling settles. Track your progress: your bend, your walking, and how the knee feels the next morning. The patients who do well are the ones who show up, do the work, and build week after week.”
Home or outpatient physical therapy?
I recommend going straight to an outpatient physical therapy clinic, for two reasons. First, getting out of the house is therapy in itself. Second, the clinic has all the equipment, so your therapist can work you harder than is possible in your living room. Home therapy visits are an option when getting a ride to the clinic is the problem, and they are a real help in that situation.
What does the research say? In the largest trial on this question, 621 patients identified as being at high risk of a poor result were randomly assigned to traditional outpatient physiotherapy or to a structured home program delivered by rehabilitation assistants under therapist supervision. At six months and at twelve months there was no clinically or statistically significant difference between them in function, knee scores, or quality of life, and the home program cost less to deliver.[2] A smaller randomized trial found the same thing at three and five months.[3]
The setting matters less than whether you do the work. As I tell every patient, your physical therapist is really there as your guide; the real work happens on your own.
Wherever you do it, the rule is the same: show up, and do the home program between sessions.
Is physical therapy supposed to hurt after knee replacement?
Therapy after a knee replacement is work, and some sessions will be uncomfortable. Here is how to tell the difference between the right kind of sore and a signal to back off.
- Soreness that settles down after you work is normal and expected. Swelling and heat that keep climbing mean you did too much.
- If you overdo it, the fix is simple: ease back, ice, elevate, and return to your exercises the next day. You are not behind. You are adjusting.
- Take your pain medicine on schedule during the hard days, especially before therapy. It is harder to chase pain than to stay ahead of it.
The kneecap work can be sore. In most knee replacements I also resurface the kneecap: the underside is removed and replaced with a plastic button, so the kneecap itself has had surgery and the tissue around it can be tight. Your therapist moves the kneecap side to side to loosen that scar tissue. Some discomfort is possible and expected, but it should not be excruciating. If it is, tell your therapist.
What if I am struggling with my exercises in the first week?
That is common, and it does not mean you are failing. Many patients feel good for the first day or two, then hit a harder stretch around days three to six as swelling builds. That dip is normal. More on it in my article on the first two weeks.
Do not skip therapy just because you are sore. Your physical therapist knows how to work with a swollen, early knee, and showing up on the rough days is how the motion comes back. Do what you can, ice afterward, and try again the next session.
Who needs more (or less) than six weeks of therapy?
Six weeks is a typical course, not a rule. Some patients reach their goals sooner. Others need longer, often because swelling was slow to settle or the knee was very stiff before surgery. If your motion stalls or starts going backward, tell your surgical team early, so the plan can change while there is still time to win that motion back. Knee stiffness that does not respond to steady work deserves an evaluation, not a wait.
If the knee stays stiff despite steady work, one option is a manipulation under anesthesia: the knee is bent for you while you are asleep, to break up scar tissue. If you end up needing one, the outcome data should reassure you. In a matched study with at least two years of follow-up, patients who had a manipulation finished with the same knee scores and the same satisfaction as patients whose recovery was uncomplicated, 88.5 percent versus 89.6 percent.[4]
After a revision knee replacement, therapy runs longer, usually about three months, and full recovery is often closer to a year.
Kneeling is its own skill, and it comes later. It is covered in kneeling after knee replacement.
“Motion is life, and life is motion. I believe that completely. We want to keep you moving after a knee replacement, but not be too aggressive while the knee is still swollen. The surgery puts in a new joint; therapy and your own daily work are what teach the knee to move again. If something feels wrong along the way, call us. I would always rather hear from you early.”
When should you call your surgeon instead of pushing through?
Some warning signs have nothing to do with therapy, and those are the ones to call about right away:
- A calf that is swollen, red, and painful
- A fever above 101.5 degrees Fahrenheit
- Drainage from your incision
- Pain that suddenly gets far worse instead of slowly better
- Motion that stalls or goes backward over several days, despite steady work (judge it week over week; one bad day is not a reason to panic)
These can point to a blood clot, an infection, a wound problem, or a knee that is stiffening, and all of them are easier to handle when caught early. You are never bothering us by calling. If you’re worried, I’m worried. Our clinic number is answered 24 hours a day. For the overall picture of recovery, see my recovery timeline.
Knee replacement recovery in Franklin, Nashville, and Middle Tennessee
I perform knee replacements at the Bone and Joint Institute of Tennessee in Franklin, on the Williamson Health campus, for patients from Franklin, Brentwood, Nashville, Spring Hill, Nolensville, Murfreesboro, and across Middle Tennessee. Every knee patient leaves with a therapy plan, and our team stays in touch through the weeks it takes to get your motion and strength back.
This article is for educational purposes only and does not replace personalized medical advice. Recovery instructions vary by individual health factors; always follow the guidance of your own surgical team. In an emergency, call 911.
References
- McGarry L, Kearney J, Rotaru J, Gunaratne R. Swelling management in total knee arthroplasty: a systematic review. JBJS Rev. 2025;13(9). doi:10.2106/JBJS.RVW.25.00109
- Barker KL, Room J, Knight R, et al. Outpatient physiotherapy versus home-based rehabilitation for patients at risk of poor outcomes after knee arthroplasty: CORKA RCT. Health Technol Assess. 2020;24(65):1-116. doi:10.3310/hta24650
- Haghpanah B, Tavakoli F, Mollaabbasi M, et al. Comparison the effect of rehabilitation at home and outpatient physiotherapy after total knee arthroplasty surgery on quality of life and knee function: a clinical trial study. Adv Biomed Res. 2024;13:51. doi:10.4103/abr.abr_177_23
- Sirignano MN, Rowe RS, Gainer JC, et al. Patients undergoing manipulation under anesthesia following primary total knee arthroplasty: are their patient-reported outcome measures inferior? J Knee Surg. 2025;38(8):407-414. doi:10.1055/a-2509-3109
