TKR stands for total knee replacement, a surgery that removes damaged cartilage and bone from your knee joint and replaces them with an artificial joint made of metal and plastic. It’s one of the most common orthopedic surgeries performed today, and roughly 90% of knee replacements are still functioning well 20 years later. Most people who get one have severe arthritis that no longer responds to medications, injections, or physical therapy.
Why the Surgery Is Recommended
Total knee replacement is typically considered after other treatments have failed. That includes anti-inflammatory medications, cortisone injections, lubricating injections, physical therapy, and sometimes earlier, less extensive surgeries. There are no absolute age or weight restrictions for the procedure.
The signs that point toward surgery are specific and functional. Moderate or severe knee pain that persists even while resting, including at night. Chronic swelling and inflammation that don’t improve with rest or medications. A visible deformity in the knee, such as the leg bowing inward or outward. If your knee limits your ability to do basic things like walk, climb stairs, or get in and out of a chair, and conservative treatments haven’t helped, you’re likely a candidate.
What Happens During the Procedure
The surgeon removes the damaged surfaces of three bones that meet at the knee: the bottom of the femur (thighbone), the top of the tibia (shinbone), and the underside of the patella (kneecap). Each surface is then reshaped and capped with a prosthetic component. The femoral component covers the rounded end of your thighbone. The tibial component resurfaces the flat top of your shinbone. The patellar component replaces the worn underside of your kneecap. A plastic spacer sits between the metal parts, creating a smooth gliding surface that mimics natural cartilage.
The surgery itself usually takes one to two hours. Some hospitals now use robotic-assisted systems, which allow the surgeon to plan and execute bone cuts with computer guidance. Cleveland Clinic data found that robotic-assisted procedures led to shorter hospital stays (roughly half a day compared to just over one day for manual surgery), though outcomes at this point are otherwise similar between the two approaches.
Risks and Complications
Serious complications are uncommon. In a large study of knee replacement patients, blood clots in the leg occurred in about 0.6% of cases, typically appearing around 9 days after surgery. Joint infection developed in about 0.5% of patients, usually surfacing around two months post-surgery. And roughly 0.5% of replacements required a revision surgery within the first year, most commonly around seven months out.
Other possible complications include stiffness if scar tissue limits your range of motion, nerve damage near the surgical site, and loosening of the implant over time. The overall picture, though, is reassuring. Among nearly 55,000 knee replacement patients tracked by researchers at Harvard, only 3.9% needed a revision within 10 years. At the 20-year mark, that number was 10.3%, meaning about 9 in 10 replacements lasted two decades or longer.
Recovery Timeline
Recovery follows a fairly predictable arc, though individual timelines vary based on age, overall health, and how consistently you do your exercises.
Weeks 0 to 6
You’ll use a walker or cane for short, frequent walks. The goal is to bend your knee to about 90 degrees by two weeks and 110 degrees by six weeks. By the end of this phase, most people can walk short distances without an assistive device. Pain and swelling are most significant during this window and gradually decrease.
Weeks 6 to 12
Most people transition to using just a cane or no device at all. Range of motion often reaches 120 degrees or more. This is when many people return to driving, desk work, and running errands. Longer walks become comfortable, and daily routines start to feel more normal.
Physical Therapy and Exercises
Physical therapy is the most important factor in your recovery. The American Academy of Orthopaedic Surgeons recommends exercising 20 to 30 minutes daily (or even two to three times daily) and walking for 30 minutes two to three times a day during early recovery. That’s a significant time commitment, but it directly determines how well your new knee functions long-term.
Early exercises focus on waking up the muscles around your knee and restoring basic movement. Quad sets, where you tighten your thigh muscle and try to press the back of your knee flat against the bed, are one of the first things you’ll do. Ankle pumps (moving your foot up and down rhythmically) help prevent blood clots and keep circulation flowing. Straight leg raises build thigh strength while your knee is still too sore for weight-bearing exercise. You’ll also do bed-supported knee bends, sliding your heel toward your buttocks to gradually increase how far the knee bends.
As you progress, exercises move to a seated position. Sitting knee bends, both supported and unsupported, push your range of motion further. Knee straightening exercises, done with a small rolled towel under your heel so the knee hangs slightly suspended, help you regain full extension. Each exercise is held for 5 to 10 seconds per repetition and repeated until the muscle feels fatigued. Sessions are short (two to three minutes per exercise) but frequent throughout the day.
Preparing Your Home Before Surgery
Getting your home set up before the procedure makes a real difference in how smoothly recovery goes, especially in the first few weeks when bending, reaching, and climbing stairs are difficult or off-limits.
If your bedroom is upstairs, set up a sleeping area on the first floor. Your mattress should be firm enough that you don’t sink into it when sitting on the edge, since you’ll be getting in and out of bed frequently. Make sure you have a bathroom or portable commode on the same floor where you’ll spend most of your day.
The bathroom needs the most modification. Install two grab bars: one to help you get in and out of the tub, and one to help you stand from a sitting position. Secure them vertically or horizontally to the wall, never diagonally, and don’t rely on towel racks (they can’t support your weight). Put non-slip mats inside the tub and on the floor outside it. Place soap and shampoo where you can reach them without standing up, reaching overhead, or twisting. A raised toilet seat makes sitting down and standing back up much easier.
Move frequently used items to a height between your waist and shoulders so you never need to bend low or reach overhead. Stock up on frozen meals, canned food, toilet paper, and personal care supplies before surgery. A few specific tools will make daily life manageable: a long-handled shoehorn, a reacher (for picking things up from the floor and helping with pants and socks), a sock aid, and a long-handled shower sponge. Keep your phone, a notepad, and essentials in a bag or basket you can carry with you or clip to your walker.