The surgery itself usually takes 1 to 2 hours from the first incision to the last stitch
Total time in the operating room is typically 60 to 120 minutes, though the exact length depends on your anatomy, the surgeon's experience, and whether any complications arise during the procedure. The surgeon removes the damaged cartilage and bone from your knee joint, then fits the artificial components into place. This is the active surgical work — the part where the surgeon is actually operating.
You should expect to spend additional time in the operating room before and after the actual surgery. Anesthesia staff will position you, place monitoring equipment, and administer anesthesia — this adds 15 to 30 minutes before the surgeon begins. After the surgeon finishes, the team closes the incision and moves you to recovery, which adds another 30 to 60 minutes. Your total time from when you enter the operating room until you leave it is usually 2 to 3 hours.
Key Takeaways
- The actual surgical work takes 1 to 2 hours, but you will spend 2 to 3 hours total in the operating room including setup and recovery.
- You will spend 1 to 3 hours in the post-anesthesia care unit (PACU) waking up and being monitored before moving to your hospital room.
- Hospital discharge happens the same day or the next morning depending on your surgeon's protocol and how quickly you recover from anesthesia.
- The entire day at the surgical facility — from arrival to discharge — typically takes 4 to 8 hours.
What happens before the surgeon starts
You arrive at the surgical facility 1 to 2 hours before your scheduled surgery time. During this period, nursing staff will check your vital signs, review your medical history, and have you change into a surgical gown. An anesthesiologist or nurse anesthetist will meet with you to discuss anesthesia options and answer questions about what to expect.
Once you move into the operating room, the anesthesia team positions you on the surgical table and places monitoring equipment — blood pressure cuff, heart monitor, pulse oximeter, and IV lines. They then administer anesthesia, which takes 10 to 20 minutes. You will be asleep before the surgeon makes the first incision. The surgical team uses this time to clean and drape your knee with sterile coverings.
The actual replacement procedure
Once you are fully anesthetized, the surgeon makes an incision down the front of your knee, usually 8 to 10 inches long. They carefully move the muscles and tendons aside to access the knee joint. The damaged cartilage and bone are removed from the end of your thighbone and the top of your shinbone using specialized cutting guides and instruments.
The surgeon then positions the artificial knee components — typically a metal piece for the thighbone, a plastic spacer, and a metal piece for the shinbone — and secures them in place. Some surgeons use bone cement; others use components designed to bond directly to your bone. The surgeon tests the knee's movement and alignment to may support proper function. This entire process takes 60 to 120 minutes depending on the complexity of your case and the surgeon's approach.
Recovery in the operating room and when ready aftermath
Once the surgeon finishes, the surgical team closes the incision with stitches or staples and applies a sterile dressing. The anesthesia is stopped, and you begin waking up — this takes 5 to 15 minutes. You are still in the operating room during this time, and the team monitors you closely as you regain consciousness.
You are then moved to the post-anesthesia care unit (PACU), sometimes called the recovery room. Here you spend 1 to 3 hours waking up completely while nurses monitor your heart rate, blood pressure, oxygen level, and pain. You may feel groggy, nauseous, or confused — this is normal and temporary. Once you are alert, your pain is controlled, and your vital signs are stable, you move to your hospital room or are discharged home, depending on your surgeon's protocol.
Same-day surgery versus overnight stay
Some surgeons perform knee replacement as same-day surgery, meaning you go home the same day. Others keep patients overnight for monitoring. Your surgeon will decide based on your age, overall health, the complexity of your surgery, and your home support system. If you have someone at home to help you and your surgery goes smoothly, same-day discharge is often possible.
If you stay overnight, you will spend the evening and night in your hospital room where nursing staff monitor your pain, help you with movement, and manage any swelling or complications. You typically leave the next morning after your surgeon rounds and clears you for discharge. The total time from arrival to discharge in an overnight stay is usually 18 to 24 hours.
Factors that can make surgery take longer
Revision surgery — replacing a knee that was previously replaced — takes longer than a first replacement, often 2 to 3 hours or more. Severe arthritis, bone loss, or unusual anatomy can also extend the surgical time. If you have had previous knee surgery, scar tissue may need to be removed first, adding 20 to 40 minutes.
Complications during surgery, such as unexpected bone damage or difficulty positioning components, can extend the procedure. Your surgeon will communicate with your family if the surgery is taking longer than expected. In most cases, a longer surgery does not mean a worse outcome — it straightforward means your case required more time and precision.
What to expect for timing on your surgery day
Plan to arrive at the surgical facility 60 to 90 minutes before your scheduled surgery time. Your actual surgery time is when the surgeon begins the procedure, not when you arrive. If your surgery is scheduled for 8:00 a.m., you might arrive at 6:30 a.m., move to the operating room around 7:15 a.m., and the surgeon begins around 7:45 a.m. to 8:15 a.m.
From start to finish — arrival through discharge — plan for 4 to 8 hours if you are going home the same day, or 18 to 24 hours if you are staying overnight. Ask your surgeon's office for a more specific timeline based on your scheduled surgery time and their facility's procedures. Bring someone to drive you home if you are having same-day surgery, as you cannot drive yourself after anesthesia.
Frequently Asked Questions
Why does it take so long if the surgery is only 1 to 2 hours?
The 1 to 2 hours is only the active surgical work. You spend additional time in anesthesia setup (15 to 30 minutes), post-operative recovery (30 to 60 minutes), and post-anesthesia monitoring (1 to 3 hours). The entire day involves arrival, pre-op preparation, surgery, and recovery — all of which add up to 4 to 8 hours total.
Can the surgery be done faster with newer techniques?
Minimally invasive techniques may reduce surgical time slightly — sometimes by 15 to 30 minutes — but the overall time in the operating room and recovery room remains similar. The surgeon's priority is precision and proper component placement, not speed. A well-executed surgery that takes longer is preferable to a rushed one.
What if my surgery takes longer than expected?
Your surgical team will update your family if the procedure is taking longer than anticipated. Common reasons include unexpected bone loss, scar tissue from previous surgery, or the need for careful adjustment of components. A longer surgery does not automatically mean complications — it often means your surgeon is taking extra time to may support the best result.
Will I be awake during any part of the surgery?
No. You receive general anesthesia, which means you are completely asleep throughout the entire procedure. You will not feel pain, hear conversations, or be aware of time passing. You wake up in the recovery room after surgery is complete.
How long after surgery can I go home?
If your surgeon performs same-day surgery, you can go home 4 to 6 hours after arriving at the facility, once you are alert and your pain is controlled. If you stay overnight, you typically leave the next morning. Your surgeon will clear you for discharge once you meet specific criteria — usually being able to move your knee slightly, managing pain with oral medication, and having stable vital signs.