The surgery itself takes 1 to 2 hours, but you'll spend 3 to 4 hours total at the surgical facility
The actual cutting, removing bone, and installing the artificial joint takes between 60 and 120 minutes. However, the time you spend in the operating room from the moment you enter until you leave is longer—usually 3 to 4 hours—because surgeons need time to position you, administer anesthesia, prepare the surgical site, and monitor you as you wake up.
The exact length depends on several factors: whether this is your first knee replacement or a revision (replacing a previous implant), the complexity of your knee damage, your overall health, and how quickly your body responds to anesthesia. A straightforward first replacement on a healthy patient typically runs closer to 60 minutes. A revision or a knee with severe arthritis or previous injury can stretch toward 2 hours or beyond.
Key Takeaways
- The surgical procedure itself lasts 1 to 2 hours, but plan for 3 to 4 hours at the facility including anesthesia and recovery time.
- You will be under general or regional anesthesia and will not be awake during the procedure.
- Most patients go home the same day or stay overnight, depending on their health and the surgeon's preference.
- Full recovery—returning to normal activities without pain—typically takes 3 to 6 months, though some improvement continues for a year.
- Physical therapy begins within days and continues for weeks or months, which is the main factor in how quickly you regain function.
What happens before the surgeon makes the first cut
You will arrive 1 to 2 hours before your scheduled surgery time. During this period, a nurse will check your vital signs, review your medical history, and confirm you have not eaten or drunk anything since midnight (or whatever time your surgeon specified). An anesthesiologist will meet with you to discuss which type of anesthesia you will receive—usually general anesthesia (you are fully asleep) or regional anesthesia (your leg is numbed but you may be sedated).
Once you are taken to the operating room, the surgical team will position you on the table, place monitoring equipment on your chest and fingers, insert an IV line if one is not already in place, and begin anesthesia. This setup phase typically takes 20 to 30 minutes. You will not remember any of this—anesthesia takes effect quickly, and your last memory will be of the anesthesiologist telling you to count backward.
The surgical steps and their timing
Once you are asleep, the surgeon cleans your knee with an antiseptic solution and drapes the area with sterile cloth. The actual incision is made, usually 8 to 10 inches long on the front of the knee. The surgeon then removes the damaged cartilage and bone from the end of your thighbone and the top of your shinbone, using specialized cutting guides to may support the cuts are precise.
Next, the surgeon cements or presses the metal and plastic components of the artificial joint into place. This step requires careful alignment because the angle and position of the implant affect how your knee moves and feels after surgery. Once the components are secured, the surgeon tests the knee's range of motion and stability, then closes the incision with stitches or staples and applies a sterile bandage. The entire surgical sequence—from incision to bandage—typically takes 60 to 120 minutes.
Recovery in the operating room and when ready aftermath
After the surgeon finishes, you remain in the operating room while anesthesia wears off. This takes 10 to 20 minutes. You will then be moved to a recovery room (sometimes called the post-anesthesia care unit, or PACU) where nurses monitor your blood pressure, heart rate, oxygen level, and pain. Most people spend 1 to 2 hours here before being discharged or moved to a hospital room.
You may feel groggy, nauseous, or confused when you first wake up—this is normal and temporary. Your knee will be wrapped in a compression bandage and possibly in a brace or immobilizer. Pain is common, and the nursing staff will offer medication to manage it. You will not be able to drive or make important decisions for the rest of the day because anesthesia affects your thinking and coordination for several hours after surgery.
Same-day discharge versus overnight hospital stay
Some surgeons perform knee replacement as an outpatient procedure, meaning you go home the same day. Others prefer to keep patients overnight for observation. The choice depends on your age, overall health, whether you live alone, and your surgeon's standard practice. If you are discharged the same day, you will typically leave 2 to 4 hours after waking up, once you can walk with crutches or a walker and your pain is controlled with oral medication.
If you stay overnight, you will be moved to a hospital room where nurses continue to monitor you and a physical therapist may visit to help you stand and take a few steps. Either way, you will need someone to drive you home and stay with you for at least the first 24 hours. You cannot drive yourself, and you should not be alone while anesthesia is still leaving your system.
Physical therapy and the weeks after surgery
The timeline after you leave the surgical facility is largely determined by how consistently you do physical therapy. Most surgeons schedule your first therapy session within 3 to 5 days of surgery. During these sessions, a physical therapist guides you through exercises to reduce swelling, restore your knee's range of motion, and rebuild the strength in your leg muscles.
You will likely attend therapy 2 to 3 times per week for 4 to 8 weeks, then continue exercises at home. Many people see significant improvement—walking without a limp, climbing stairs, bending the knee to 90 degrees or more—within 6 to 8 weeks. However, full recovery, including return to activities like hiking or recreational sports, often takes 3 to 6 months. Some patients continue to see gradual improvement for up to a year after surgery.
Factors that can make surgery take longer
A revision surgery (replacing an implant that has worn out or failed) typically takes longer than a first replacement because the surgeon must remove the old components, which may be cemented in place or have bone grown around them. This can add 30 minutes to an hour to the procedure.
Severe arthritis, bone loss, or previous knee injuries can also extend surgical time because the surgeon must spend more time preparing the bone surfaces and ensuring proper alignment. Patients who are obese or have significant muscle atrophy may require extra time for positioning and careful handling. Complications discovered during surgery—such as unexpected bone damage or ligament injury—can also lengthen the procedure, though this is uncommon.
Frequently Asked Questions
Will I be awake during knee replacement surgery?
No. You will receive either general anesthesia (fully asleep) or regional anesthesia (your leg is numbed and you are sedated). You will not feel pain or be aware of what is happening. The anesthesiologist monitors you throughout and adjusts medication as needed.
Can I go home the same day as my surgery?
Many patients do, though some surgeons prefer an overnight stay. Your surgeon will discuss this with you beforehand based on your health, age, and home situation. If you go home the same day, you must have someone drive you and stay with you for at least 24 hours.
How long before I can walk normally after knee replacement?
Most people walk with crutches or a walker for 2 to 6 weeks after surgery. Walking without information typically becomes possible within 4 to 8 weeks, though your gait may still be slightly stiff. Full, pain-free walking usually takes 3 to 6 months and depends heavily on how much physical therapy you do.
What if my surgery takes longer than expected?
Longer surgery time is usually not a cause for concern—it straightforward means your surgeon needed extra time to may support proper alignment or address unexpected findings. Your surgeon will explain what happened during a follow-up visit. Longer procedures do not typically mean worse outcomes.
When can I return to work after knee replacement?
If your job is desk-based, you may return within 2 to 4 weeks. If your work requires standing, walking, or physical labor, you will likely need 6 to 12 weeks off. Your surgeon will give you specific guidance based on your job demands and your recovery progress.