The operation itself lasts one to three hours, depending on complexity and your surgeon's approach

A standard knee replacement surgery takes between 60 and 120 minutes once you are in the operating room. straightforward cases with no prior knee surgery or complications may finish closer to one hour. Complex cases — where bone is severely damaged, you have had previous knee surgery, or your anatomy is unusual — can stretch toward two or three hours. The surgeon's experience and the specific technique used (traditional open surgery versus minimally invasive) also affect timing.

The time you spend in the hospital or surgical facility is much longer than the operation itself. You will arrive one to two hours before surgery for check-in, bloodwork, and anesthesia preparation. After the operation ends, you spend one to three hours in recovery while anesthesia wears off and nurses monitor your vital signs. Total time from arrival to discharge from recovery is typically four to six hours.

Key Takeaways

  • The actual surgical procedure lasts one to three hours, with most cases finishing in 90 minutes.
  • You will spend an additional three to four hours in pre-surgery preparation and post-surgery recovery.
  • Minimally invasive techniques may be slightly faster than traditional open surgery, though the difference is usually under 30 minutes.
  • Your total time at the facility from arrival to leaving recovery is typically four to six hours.

What happens during the operation

The surgeon makes an incision over the front of your knee, usually four to six inches long. They remove the damaged cartilage and bone from the end of your thighbone and the top of your shinbone. Metal and plastic components are then fitted to replace the damaged surfaces. The surgeon tests the knee's movement and alignment before closing the incision with stitches or staples.

In a minimally invasive approach, the surgeon uses smaller incisions and specialized instruments to reach the knee joint. This technique can reduce swelling and recovery time, though the actual operation may take only 10 to 20 minutes less than traditional surgery. Not all patients are candidates for minimally invasive surgery — it depends on your anatomy and the extent of damage.

Why some operations take longer than others

Previous knee surgery adds time because scar tissue must be removed and the surgeon must work around old implants or repairs. Severe arthritis that has damaged bone extensively requires more careful bone preparation. If you have bone loss, the surgeon may need to use bone grafts or specialized implants, which adds 30 to 60 minutes. Obesity can make access to the joint more difficult and slow the procedure.

Your surgeon's experience matters. A surgeon who performs dozens of knee replacements per month may work faster than one who does fewer, though speed is not the only measure of quality. The type of implant chosen also plays a role — some designs require more precise positioning and take longer to seat properly.

Anesthesia and recovery room time

You will receive either general anesthesia (you are fully asleep) or regional anesthesia (your lower body is numb but you are awake or lightly sedated). General anesthesia takes 10 to 15 minutes to administer and another 30 to 60 minutes to wear off after surgery ends. Regional anesthesia (spinal or epidural block) takes 10 to 20 minutes to place and may wear off more slowly, sometimes lasting several hours.

In the recovery room, nurses monitor your heart rate, blood pressure, oxygen level, and pain. You will not leave recovery until you are alert, your vital signs are stable, and your pain is controlled. If you received general anesthesia, you may feel groggy or nauseous for the first hour. Most people are ready to move to a hospital room or go home one to three hours after the operation ends.

Hospital stay versus outpatient surgery

Some knee replacements are done as outpatient procedures, meaning you go home the same day. Others require an overnight or two-night hospital stay. Your surgeon will recommend based on your age, overall health, home support, and how well you recover from anesthesia. Outpatient surgery means you leave four to six hours after the operation ends. Hospital stays typically mean you leave the next morning or the morning after that.

If you stay overnight, you will spend that time in a hospital room where physical therapists begin gentle movement exercises and nurses manage your pain and swelling. The length of stay does not change the operation time itself — it reflects what happens after surgery and how quickly you can safely go home.

What to expect on the day of surgery

Arrive at the facility two hours before your scheduled operation time. You will change into a hospital gown, have an IV placed, and meet your anesthesiologist and surgical team. The surgeon will mark the surgical site on your knee. You will be taken to the operating room about 30 minutes before the scheduled start time.

After surgery, you will wake in recovery. A nurse will ask you to move your toes and bend your knee slightly — this happens within the first hour. You may feel pain, but medication is available. Once you are alert and stable, you will either go to a hospital room or be discharged with written instructions and a prescription for pain medication.

Factors that might delay your surgery

If you arrive with a fever, active infection, or unstable blood pressure, surgery may be postponed. Blood clots, heart rhythm problems, or other complications discovered during pre-surgery testing can delay the procedure. If the operating room is running behind schedule, your surgery time may shift by 30 minutes to an hour.

Once you are in the operating room, the surgeon may discover unexpected bone damage or other issues that require adjustments to the plan. This can add 20 to 45 minutes to the operation. Your surgical team will communicate any significant delays to your family in the waiting room.

Frequently Asked Questions

Can I eat or drink before surgery?

No. You will be told to stop eating at midnight the night before and stop drinking clear liquids two hours before arrival. This prevents vomiting during anesthesia, which can be dangerous. Follow your surgeon's specific instructions — they may differ slightly.

Will I be awake during the operation?

That depends on the type of anesthesia. With general anesthesia, you are fully asleep and remember nothing. With regional anesthesia (spinal or epidural), you are awake but cannot feel your leg. You may hear conversation in the operating room, but you will not feel pain. Tell your anesthesiologist if you prefer to be asleep.

What if something goes wrong during surgery?

Your surgical team monitors your heart, blood pressure, oxygen, and other vital signs continuously. If a problem arises, the surgeon can adjust the plan or call for additional support. Serious complications during knee replacement are uncommon, but your team is trained to handle them.

How long until I can walk after surgery?

Physical therapists begin gentle movement in recovery or the next morning. Most people walk with a walker or crutches within 24 hours. Full weight-bearing and walking without information typically takes two to six weeks, depending on your progress and your surgeon's protocol.

Why does my surgery time keep changing?

Operating room schedules shift when emergencies arrive or when previous surgeries run long. Your surgeon's office will call if your time changes significantly. Arrive at your originally scheduled time unless you are told otherwise.