Most people walk without a stick by six to eight weeks and are back to normal daily life by around three months.
Full recovery takes about a YEAR. The knee keeps getting stronger, less swollen and less noticeable long after it stops being the first thing you think about in the morning.
Two things decide how well you do:
- how far your knee bent BEFORE surgery, and
- whether you get it fully STRAIGHT in the first six weeks
Week by week
- Days 0 to 3: you stand and walk on the new knee the same day or the next, with a walker. Ankle pumps and thigh squeezes start straight away. Most people go home within one to three days
- Week 1: knee nearly flat, bending past about 70 degrees. Short, frequent walks around the house. This is not the week for step counts
- Weeks 2 to 3: bending to around 90 degrees. Most people move from the walker to one crutch or a cane. Sleep is often at its WORST around now
- Weeks 4 to 6: bending past 110 degrees. Stationary bike, light ankle weights, walking without an aid on flat ground. Most daily tasks come back
- Weeks 7 to 12: bending past 120 degrees, no walking aid, step-ups and uneven ground. Back to desk work, and to physical work toward the end of this window
- Months 3 to 12: strength and stamina. Slow and undramatic, and the part nobody warns you about
Your surgeon may give you different targets. Use theirs.
Bend is what everyone measures. Straight is what costs you if you lose it.
Get it straight first
- A knee that won’t go fully straight makes your thigh muscle work every single step just to hold you up. You feel it as tiredness, limping and a sore thigh
- A few degrees short is fine. More than about 5 degrees starts to cost you. More than 15 is a real problem
- The good news: about 1 in 10 people have a knee that won’t straighten early on, and almost all of them get it straight within a year with work
- Prop the heel, not the knee. Lie with a rolled towel under your ankle and nothing under the knee, and let gravity do the work
- No pillow under the knee in bed for the first six weeks. It feels wonderful and quietly trains the knee to stay bent
Normal things that frighten people
- Swelling that lasts months. It peaks around SIX weeks, not in the first week. It travels down to the ankle and foot and up the thigh. Puffy at 6pm and slimmer at 8am is normal
- A warm knee. A new knee still feels warmer than the other one at three months, and slightly warmer even at a year. Warm on its own is expected
- Night pain. Common for the first six weeks, then it usually turns the corner
- Clicking. Metal and plastic make noise. Painless clicking is not a problem
- A numb patch beside the scar, usually on the outer side. A small skin nerve is cut during surgery. The patch shrinks over months and may never fully go
- Weeks 3 and 4 feeling worse than week 2. Poor sleep, rising swelling and the relief of surgery wearing off all land at once. You are not going backward
What helps
- Elevate with the foot above the knee and the knee above the hip, not with a pillow bent under the knee
- Ice for up to 20 minutes with a towel between the ice and your skin, then give it at least 40 minutes off
- Little and often beats one long session. Short walks and exercises several times a day keep swelling down better than one big effort
- Measure yourself against your own knee, not your neighbor’s. A knee that bent to 100 degrees before surgery rarely reaches 130 after it
- Don’t panic if therapy sessions run out. Studies comparing supervised therapy with a good home program find very similar results for most people. The work matters more than the setting
If the knee stops bending
About 1 to 7 in 100 people (figures vary with how stiffness is defined) develop a genuinely stiff knee after knee replacement. If bending has STOPPED improving at around eight weeks, raise it then, not at four months.
- The fix is often a manipulation under anesthetic: you’re asleep and the surgeon bends the knee to break down the scar tissue
- Timing is everything. Done within 12 weeks, people gained on average around 36 degrees of bend. Done after 12 weeks, around 17
- This is one of the few places in knee recovery where waiting costs you something you can’t get back
When can I…
- Drive: usually around four to six weeks, once you can brake hard without hesitating and are off strong painkillers. Your surgeon and your insurer decide, not a website
- Go back to work: six weeks for desk work, up to twelve for work on your feet all day. Expect to be tired for longer than you are sore
- Fly: most people can within a few weeks. Get up every hour or two, do ankle pumps in your seat, drink water, and ask about compression stockings for long flights
- Take stairs: up with the good leg, down with the operated leg. Hold the rail. One step at a time until it feels steady
- Kneel: often uncomfortable, and the most common long-term complaint. Uncomfortable is not harmful. It won’t damage the new knee. A cushion helps
- Sleep: on your back, or on your side with a pillow between your knees
- Play sport: walking, swimming, cycling, golf and doubles tennis are generally fine. Running and jumping sports are usually discouraged. If running matters to you, have that conversation with your own surgeon
How long will it last?
About 9 in 10 knee replacements are still going at 20 years, and more than 8 in 10 at 25 years. The most common reasons for a redo are the implant loosening and infection.
Call your surgeon today if
- Your calf is painful, tender or newly swollen: possible clot in the leg
- You are suddenly short of breath or have chest pain: call emergency services. A clot can travel to the lung
- The wound is red, spreading, weeping or draining
- You have a fever or chills
- The knee is getting MORE painful, not less, at rest or with activity
A knee infection often comes WITHOUT a fever. Don’t let a normal temperature talk you out of calling about a knee that’s getting worse.
Mention it at your next review if
- Bending has stopped improving at around eight weeks
- The knee still won’t go fully straight at six weeks
- Numbness or tingling isn’t settling
- Pain isn’t controlled by your medication
Bend comes back with work. Straight has to be won early.