Most people spend the weeks before a knee replacement resting the knee and waiting. Those weeks are one of the best chances you'll get to make recovery easier, and here's how to use them without aggravating a knee that already hurts.
A client of mine got her surgery date for a knee replacement in early spring, about ten weeks out. When she told me, she said, "So I guess we'll pause until I'm healed up." I understood why she'd think that. Her knee hurt, she'd been favoring it for two years, and the surgery was supposed to be the thing that fixed it. Why work on a joint that's about to be replaced?
I asked her to give me those ten weeks instead. Not to train the knee hard, but to get the rest of her ready for what was coming. She did, and her surgeon's physical therapist told her at her first post-op visit that she was ahead of most of the people he saw. That's not luck. That's what happens when you treat the time before surgery as part of the recovery instead of a waiting room.
Yes, in almost every case, as long as your surgeon is on board. The new joint will be a big improvement, but it doesn't come with new muscles attached. The strength you walk into the operating room with is roughly the strength you'll have to work with when you're trying to get out of a hospital bed, climb the steps to your front door, and get through physical therapy. Research on knee replacement keeps pointing to the same thing: people who have stronger thigh muscles and better function before surgery tend to have an easier time getting that function back afterward.
There's a name for this kind of training. Physical therapists call it prehabilitation, or prehab. It's simply rehab done in advance, while you still have two working legs and no incision to protect.
If I could only pick one muscle group to train before knee surgery, it would be the quadriceps, the big muscles on the front of your thigh. They're what straighten your knee, and they're what lower you into a chair and lift you back out of it.
Here's the problem. Years of a painful knee usually means years of quietly avoiding using it. You lean on the railing, push up from the chair with your arms, step up with the good leg every time. Your quads on the sore side get weaker and weaker without you noticing. Then surgery adds swelling and pain on top, and swelling has a way of switching the quads off even further. Starting from a stronger place gives you more room to lose before you hit the point where everyday things become hard.
This is not about pushing through knee pain. The goal is to build strength around the joint using movements your knee tolerates, and to keep the rest of your body strong at the same time. I keep it simple, and I adjust everything to how the knee feels that day.
For the knee itself, we usually start with quad sets, where you sit with your leg straight and tighten the front of your thigh as hard as you can for a few seconds. It looks like nothing, and it's one of the first things your therapist will ask you to do after surgery, so learning it now pays off twice. Straight leg raises build on that. From there, we add sit-to-stands from a chair, using a higher seat if the knee complains, along with partial squats to a comfortable depth, step-ups onto a low step, and hamstring work with a band or machine.
For everything else, we train your hips, your good leg, your upper body, and your core. Strong glutes and hips take pressure off the knee and help you walk well again. A strong good leg does a lot of the work in those first weeks. And strong arms and shoulders matter more than people expect, because you'll be pushing yourself up from beds, chairs, and toilets, and leaning on a walker or crutches for a while.
Cardio stays gentle. A stationary bike with the seat set a little high is often the most comfortable option for an arthritic knee, and walking is fine if it doesn't flare things up. If you've been told that a painful knee means you shouldn't lift at all, I'd point you to what I wrote about [why arthritis is a reason to start lifting, not stop](/blog/arthritis-isnt-a-reason-to-stop-lifting). The same idea applies here.
This is the question I get most, and it's a fair one. My general rule with clients is that mild discomfort during an exercise is acceptable if it settles back down within a day and doesn't leave the knee more swollen or stiff the next morning. Sharp pain, pain that keeps climbing as you go, or a knee that's noticeably worse the next day means we change something: less depth, less weight, a different exercise. There is almost always a version of the movement that your knee will put up with.
Your surgeon and physical therapist have the final say, especially if you have other conditions like heart disease or a history of blood clots. Tell them you're planning to train before surgery. Most will be glad to hear it.
Prehab isn't only exercise. Use some of those weeks to practice the things you'll need to do right after surgery. Get in and out of the chair you'll recover in. Practice getting on and off the toilet without pulling on the towel bar. If you'll be using a walker, borrow one and get used to it on flat ground. Clear rugs and clutter out of the paths you'll be walking at home. These sound small, but the first week home is a lot easier when none of it is new.
As soon as you know surgery is coming. Even four to six weeks of consistent training is worth doing, and more time is better. Two or three sessions a week is plenty. If your surgery date is only a couple of weeks away, you can still learn the exercises you'll be doing in rehab and get comfortable with them, which takes a lot of the stress out of those first PT appointments.
And when the surgery is behind you, the training doesn't stop. Your physical therapist handles the early rehab. After you're discharged from PT, that's when a lot of people stall out, still a little weak and a little cautious. Picking strength training back up at that point is what gets you all the way back, the same way I describe in [rebuilding strength after a hospital stay](/blog/rebuilding-strength-after-a-hospital-stay).
My client was walking her neighborhood in Affton without a cane five weeks after her surgery. She says the ten weeks of training before it were the best decision she made in the whole process, and she's still lifting with us twice a week.
If you have a knee replacement on the calendar, or you suspect one is coming, you don't have to just wait for it. Helping people across South County and the St. Louis area get strong before surgery and stay strong after it is exactly what our [geriatric training program](/services/geriatric-training) is built for.
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