The surgery itself takes 1 to 2 hours, though you'll spend 3 to 4 hours total at the surgical facility

The actual operation—from the first incision to the last stitch—usually runs between 60 and 120 minutes. Most knee replacements fall in the 90-minute range. However, the total time you spend at the surgical center is much longer because of preparation, anesthesia, and recovery in the post-op area.

Your surgeon will need time before the operation begins to position you, sterilize the surgical site, and place monitoring equipment. After the surgeon finishes, the anesthesiologist manages your waking process, and nurses monitor your vital signs and pain level before you move to a recovery room. Plan to be at the facility for 3 to 4 hours from arrival to discharge.

Key Takeaways

  • The surgical procedure itself typically lasts 60 to 120 minutes, with 90 minutes being most common.
  • Total time at the surgical facility is usually 3 to 4 hours, including prep, surgery, and when ready recovery.
  • Complex cases, previous knee surgery, or bone deformity can extend operating time by 30 to 60 minutes.
  • You will not be awake during the operation and should arrange transportation home since you cannot drive after anesthesia.
  • Hospital stays for knee replacement are typically same-day or overnight, depending on your surgeon's protocol and your overall health.

Why the timing varies between patients

Several factors can make your surgery shorter or longer than the standard 90 minutes. A straightforward first knee replacement on a patient with no prior knee surgery usually takes the least time. If you have had previous knee surgery, arthritis damage that is severe, or bone deformity, your surgeon will need extra time to work around scar tissue or reshape bone.

Your body size and bone density also matter. Larger patients or those with very dense bone may require more time for the surgeon to make precise cuts and position the implant. Age alone does not determine length—a healthy 75-year-old may have a faster surgery than a 55-year-old with multiple joint problems.

If you are having both knees replaced in one session (bilateral replacement), expect 2.5 to 3.5 hours of operating time total, not double. The surgeon can work more efficiently on the second knee because the setup is already complete.

What happens during those 90 minutes

The surgeon makes an incision, usually 8 to 10 inches long, down the front of your knee. They then remove the damaged cartilage and bone from the end of your thighbone and the top of your shinbone. This removal and reshaping takes the most time because precision matters—even a few millimeters off affects how the knee moves after surgery.

Once the bone surfaces are prepared, the surgeon cements or presses the metal and plastic components into place. They test the knee's movement and alignment before closing the incision in layers. The final steps—closing the skin, explore a sterile dressing, and moving you to recovery—happen quickly once the implant is find.

Recovery room time before you go home

After surgery ends, you move to a post-anesthesia care unit (PACU) where nurses monitor your heart rate, blood pressure, oxygen level, and pain. This phase typically lasts 1 to 2 hours. You will wake gradually—some people feel alert within 30 minutes, while others take longer. Nurses will check that you can move your toes and that your pain is manageable with medication.

Before discharge, you need to urinate on your own (if a catheter was used), keep food and fluids down without nausea, and be able to stand or transfer with help. You will receive written discharge instructions, pain medication, and a list of warning signs. A physical therapist may visit to show you basic exercises or how to use crutches or a walker.

Same-day surgery versus overnight hospital stay

Most knee replacements are now done as same-day outpatient surgery, meaning you go home the same day. Your surgeon will discharge you once you meet the criteria above—usually 3 to 4 hours after the operation ends. You must have a responsible adult drive you home and stay with you for at least the first night.

Some patients stay overnight in the hospital, particularly if they live alone, have multiple health conditions, or had complications during surgery. An overnight stay lets nurses manage pain and monitor for blood clots or infection. If you stay overnight, you will typically go home the next morning after a physical therapist works with you and your surgeon confirms you are ready.

Timeline from arrival to leaving the building

Here is what a typical day looks like. You arrive 1 to 2 hours before your scheduled surgery time for check-in and pre-op preparation. The surgical team reviews your medical history, starts an IV, and answers last-minute questions. You then move to the operating room 30 to 60 minutes before your surgery slot.

Surgery runs 60 to 120 minutes. Recovery in the PACU takes 1 to 2 hours. If all goes well and you are cleared for same-day discharge, you leave 3 to 4 hours after the operation ends. If you stay overnight, you will be moved to a hospital room after PACU recovery and discharged the following morning.

What to expect in the days after surgery

The first 24 to 48 hours after surgery are the most intense. Pain is usually highest on day 1 and improves gradually. You will take prescribed pain medication, ice the knee regularly, and keep your leg elevated. A physical therapist will visit your home or you will attend outpatient sessions to begin gentle movement and strengthening.

Most people can walk short distances with a walker or crutches within a few days. Swelling peaks around day 3 to 5 and then slowly decreases. You will have follow-up appointments with your surgeon at 2 weeks, 6 weeks, and 12 weeks to check healing and progress. Full recovery—when you can return to normal activities without pain or swelling—typically takes 3 to 6 months.

Frequently Asked Questions

Can the surgery take longer than 2 hours?

Yes. Patients with severe arthritis, previous knee surgery, bone deformity, or infection may have operations lasting 2.5 to 3 hours. Your surgeon will discuss this risk during your pre-op visit if your imaging or history suggests a longer procedure.

Will I be asleep the whole time?

Yes. You receive general anesthesia or regional anesthesia (numbing from the waist down) plus sedation. You will not feel pain or remember the surgery. The anesthesiologist monitors you throughout and wakes you gradually once surgery is complete.

What if I need to use the bathroom during recovery?

Nurses will help you use a bedpan or commode while you are still in the recovery room. Once you are more alert and pain is controlled, they will help you walk to a bathroom or use a urinal. Do not try to get up alone—ask for help every time.

Why does it take so long just to go home if surgery is only 90 minutes?

Pre-op preparation (IV, monitoring setup, positioning) takes 30 to 60 minutes. Post-op recovery and monitoring take another 1 to 2 hours. Your body needs time to wake from anesthesia safely, and nurses must confirm you can move, breathe well, and manage pain before discharge.

Is same-day surgery safe, or should I stay overnight?

Same-day surgery is safe for most patients and is now standard. Overnight stays are recommended if you live alone, have serious health conditions, or your surgeon has concerns about your specific situation. Discuss your personal risk factors with your surgeon before the operation.