A new knee can give you back walks, stairs and sleep without pain. Physical therapy is how you get there. Here is what the road usually looks like, week by week.
Total knee replacement is one of the most common joint surgeries, and most people are very glad they had it. But the surgery is only half the job. The other half is the work you do afterward to bend, straighten and strengthen your new knee. That work is physical therapy.
Every person heals at their own pace, and your surgeon's protocol always comes first. Still, it helps to know what to expect. Below is a general guide to each stage of recovery, the motion goals therapists watch, how to handle swelling, and the warning signs that mean you should call your surgeon.
Before Surgery: Why "Prehab" Helps
Prehab is physical therapy before your operation. If you have a few weeks before your surgery date, it is worth using them. Going into surgery stronger and better prepared tends to make the first weeks afterward easier.
- Strengthen the thigh and hip muscles that will support your new knee.
- Practice the exercises you will do after surgery, so they feel familiar.
- Learn to use a walker or crutches and how to get in and out of bed, a chair and a car.
- Set up your home by clearing paths, removing loose rugs and planning where you will rest.
Weeks 0–2: Protect, Move and Manage Swelling
Most people start moving the knee within a day of surgery, often before they leave the hospital. The first two weeks are about safe walking, gentle motion and controlling pain and swelling.
Typical goals in this stage:
- Walk safely with a walker or crutches, around the home and to the bathroom.
- Get the knee as straight as possible. Full straightening is one of the most important early goals.
- Start bending the knee a little more each day.
- Wake up the thigh muscle with exercises like quad sets, heel slides and ankle pumps.
Getting to a clinic can be hard in the first weeks. That is where in-home therapy helps. A licensed therapist comes to your home, checks your setup for fall risks and works on the exact tasks you need, like stairs, the shower and getting up from your favorite chair.
Weeks 3–6: Build Motion and Strength
As pain and swelling settle, therapy shifts toward more bending, more strength and better walking. Many people move from a walker to a cane during this stage, as their therapist and surgeon advise.
- Range of motion: stationary bike work, stretches and hands-on therapy to keep gaining bend.
- Strength: leg presses, step-ups, mini squats and hip exercises.
- Balance: standing drills that help you feel steady on uneven ground.
- Walking: working toward a smooth, even step without a limp.
At our Fair Lawn clinic, patients can use the AlterG anti-gravity treadmill. It lets you walk while carrying only part of your body weight. That makes it possible to practice a normal walking pattern earlier and with less pain, then add weight back step by step. Your therapist will decide if and when it fits your plan.
Weeks 6–12: Get Stronger and Get Back to Life
By now most people are walking without a device, driving (once the surgeon clears it) and doing more around the house. Therapy now focuses on strength, endurance and confidence.
- Heavier strength work for the thigh, hip and calf.
- Going up and down stairs step over step.
- Longer walks and more time on the bike.
- Balance training to lower your risk of falls.
Strength often lags behind motion. It is normal for the thigh to feel weaker than the other side for months. Keep up your home exercises even after formal therapy ends.
Return to Activities
Many people return to their usual daily routine within about three months, and keep improving for up to a year. Low-impact activities are usually encouraged: walking, cycling, swimming, golf and dancing. Many surgeons advise against high-impact activities like running and jumping sports to protect the implant. Ask your surgeon what is right for you.
Range-of-Motion Goals: General Guidance
Therapists track two numbers: how straight the knee gets (extension) and how far it bends (flexion). These are general targets, not rules. Your surgeon and therapist will set your own.
Typical motion targets
- Extension: work toward a fully straight knee (0 degrees) as early as possible. A knee that stays bent can cause a limp and pain.
- Early flexion: about 90 degrees of bend in the first few weeks.
- Later flexion: about 110 to 120 degrees by roughly 6 to 12 weeks. That is enough for most daily tasks, like stairs, sitting and getting out of a car.
Managing Swelling
Swelling is normal and can last for several months. It often gets worse after a busy day. Too much swelling makes the knee stiff and harder to bend, so keeping it down matters.
- Elevate: raise your leg with the ankle above the heart, keeping the knee straight. Avoid a pillow under the knee.
- Ice: use cold packs as your care team directs, with a cloth between the ice and your skin.
- Move: ankle pumps and short, frequent walks help fluid move out of the leg.
- Pace yourself: spread activity through the day instead of doing it all at once.
Common Setbacks
- Stiffness: if bending stalls, tell your therapist and surgeon early. Stiffness is easier to fix sooner rather than later.
- Trouble sleeping: night pain is common in the first weeks and usually improves.
- Bad days: a jump in pain or swelling after a busy day is common. Rest, elevate and ice, then ease back in.
- Skipping home exercises: the time between visits matters as much as the visits themselves.
- Clicking or numbness: some clicking and a numb patch near the scar are common. Ask your surgeon if you are unsure.
When to see a doctor right away
Call your surgeon right away if you notice:
- Pain, swelling, warmth or redness in your calf, which can be a sign of a blood clot.
- Fever or chills.
- Drainage from the wound, or redness and warmth that is spreading.
- Pain that suddenly gets much worse and does not ease with rest.
Call 911 for chest pain or shortness of breath. These can be signs of a blood clot in the lungs, which is an emergency.
Getting Started With Holsman
Our physical therapy team works with knee replacement patients at clinics across New Jersey and New York, including Fair Lawn, Paterson and Lyndhurst. We also offer in-home therapy for the early weeks, and fall prevention training as you get more active. You may also like our guide to fall prevention for seniors.
You can schedule physical therapy, occupational therapy and speech therapy directly. Some insurance plans require a referral for coverage; our staff will verify your benefits. See our insurance page or contact us to get started.
Frequently Asked Questions
How long is physical therapy after a knee replacement?
Formal therapy often lasts about 6 to 12 weeks, though it varies. Most people keep improving for up to a year with home exercises.
How much should my knee bend after a knee replacement?
A common goal is about 110 to 120 degrees of bend by 6 to 12 weeks, with a fully straight knee. Your surgeon and therapist will set your own targets.
How long does swelling last after knee replacement?
Some swelling is normal for several months. Elevating the leg, icing as directed, gentle movement and pacing your activity all help.
Can I do physical therapy at home after knee surgery?
Yes. In-home therapy is a good option for the first weeks, when getting to a clinic is hard. Many people then move to a clinic for strength work.
Do I need a referral for physical therapy after knee replacement?
You can schedule physical therapy directly. Some insurance plans require a referral for coverage; our staff will verify your benefits.
What is the AlterG treadmill?
It is an anti-gravity treadmill that lets you walk while carrying only part of your body weight. It is available at our Fair Lawn adult clinic.
This article is for general education and isn't a substitute for an evaluation by a licensed clinician.