The surgery itself usually lasts one to three hours

A total knee replacement typically takes between 60 and 120 minutes once you are in the operating room. The exact time depends on your anatomy, the complexity of your knee damage, and how straightforward the surgeon finds the procedure. A surgeon working on a first knee replacement in someone with uncomplicated arthritis may finish in 90 minutes. Someone with previous knee surgery, bone loss, or alignment problems may take closer to two hours or slightly longer.

The time on the operating table is not the same as your total time at the hospital. You will spend additional time in pre-op preparation, recovery, and post-operative monitoring. Plan to be at the facility for four to six hours total on surgery day, even though the actual cutting and implant placement takes only one to two hours.

Key Takeaways

  • The surgical procedure itself lasts between one and two hours, depending on your knee's condition and the surgeon's experience.
  • You will spend one to two hours in pre-operative preparation, including anesthesia setup and final positioning.
  • Recovery in the post-operative area takes one to two hours as you wake from anesthesia and your vital signs stabilize.
  • Total time at the hospital or surgical center ranges from four to six hours, not counting the time before you arrive or after discharge.
  • Complications during surgery, such as bone loss or scar tissue, can extend the procedure by 30 minutes to an hour.

What happens before the surgeon starts

Before the actual surgery begins, you will go through pre-operative preparation that typically takes 45 minutes to 90 minutes. You will change into a surgical gown, have an IV line placed, and meet with the anesthesiologist. The anesthesiologist will review your medical history, current medications, and any allergies or previous reactions to anesthesia. This conversation is critical because it determines which type of anesthesia you receive — usually general anesthesia combined with a regional nerve block for pain control.

Once you are in the operating room, the surgical team will position you on the operating table, explore monitoring equipment (blood pressure cuff, heart monitor, oxygen sensor), and begin administering anesthesia. You will be asleep before the surgeon makes the first incision. This setup phase takes 15 to 30 minutes and is included in your total pre-operative time.

The steps during the actual procedure

The surgeon makes an incision down the front of your knee, usually 8 to 10 inches long. They then remove the damaged cartilage and bone from the end of your femur (thighbone) and tibia (shinbone). This part of the procedure takes 20 to 30 minutes and involves using specialized cutting guides to may support the bone surfaces are shaped correctly for the implant.

Next, the surgeon cements the metal and plastic components into place. The femoral component (metal piece) goes on the thighbone, the tibial component (metal base with plastic spacer) goes on the shinbone, and sometimes a patellar component (plastic button) is attached to the kneecap. Cementing and positioning these pieces takes another 20 to 30 minutes. The surgeon tests the knee's movement and alignment before closing the incision with stitches or staples, which takes 10 to 15 minutes.

If you have a complication such as bone loss that requires a bone graft, or if scar tissue from a previous surgery makes access difficult, the procedure can extend by 30 minutes to an hour. The surgeon will inform you before surgery if they anticipate a longer case.

Recovery time in the post-operative area

After the surgeon closes your incision, you move to the post-operative recovery area (sometimes called the PACU, or post-anesthesia care unit). You will still be asleep or drowsy as the anesthesia wears off. A nurse will monitor your heart rate, blood pressure, oxygen level, and pain level every 15 minutes. This phase typically lasts one to two hours.

During this time, you may feel groggy, nauseous, or cold — all normal responses to anesthesia. The nursing staff will manage your pain with medication and keep you warm with blankets. Once your vital signs are stable, you are alert enough to follow commands, and your pain is controlled, you will be moved to a regular hospital room or discharged to home (if you had the procedure at an outpatient center).

Why some surgeries take longer than others

A straightforward total knee replacement on someone with no previous knee surgery and good bone quality takes closer to 60 to 90 minutes. If you have had prior knee surgery, arthroscopic procedures, or meniscus repairs on the same knee, scar tissue can make the surgeon's work slower and more careful. Removing scar tissue safely adds 15 to 30 minutes.

Bone loss from severe arthritis or osteoporosis may require the surgeon to use bone grafts or special augments to build up the surface before placing the implant. This adds 20 to 40 minutes. Severe misalignment of your leg or knee instability can also extend the procedure. The surgeon will discuss these factors with you before surgery if imaging or your medical history suggests a more complex case.

What to expect on the day of surgery

You will be asked to arrive at the surgical facility one to two hours before your scheduled surgery time. Check-in, final paperwork, and vital sign checks happen during this window. You will meet with the surgical team again, including the surgeon and anesthesiologist, who will answer any last-minute questions.

You will be called back to pre-op, where the timeline described above begins. From that point, expect to be at the facility for four to six hours total. Have someone drive you home — you cannot drive yourself the day of surgery because of the anesthesia. Plan to rest at home for the remainder of the day. Most people feel tired and sore but are awake and alert by evening.

Hospital stay versus outpatient surgery

Some knee replacements are done as outpatient procedures, meaning you go home the same day. Others require an overnight hospital stay. The length of the surgery itself does not determine this — your overall health, age, and ability to manage pain and mobility at home do. A healthy 55-year-old with good home support might go home the same day. A 75-year-old with other health conditions or no one at home to help might stay overnight.

If you stay overnight, you will spend the evening and night in a hospital room where nurses monitor your pain, help you with physical therapy exercises, and manage any swelling or complications. You will be discharged the next morning once you can walk safely with a walker or crutches and your pain is controlled with oral medication. The overnight stay does not change how long the surgery itself takes — it only affects your recovery location after surgery.

Frequently Asked Questions

Can the surgeon tell me before surgery how long mine will take?

Yes. If your X-rays or previous imaging show bone loss, severe arthritis, or misalignment, your surgeon will likely tell you the procedure may take longer than average. If you have had prior knee surgery, mention that at your pre-operative visit so the surgeon can plan accordingly. Most surgeons give a time range rather than an exact number.

What if I wake up during surgery?

Waking during surgery is extremely rare with modern anesthesia monitoring. The anesthesiologist watches your brain activity and adjusts medication to keep you asleep and pain-free throughout. If you are concerned about this, discuss it with your anesthesiologist before surgery — they can explain their monitoring methods and address your specific worries.

Does a longer surgery mean a worse outcome?

Not necessarily. A longer surgery usually means your knee was more complex, not that something went wrong. A surgeon who takes extra time to position an implant correctly or remove scar tissue carefully is doing what is needed for your specific anatomy. Rushing through a complex case would be worse than taking the time required.

Will I be in pain during recovery in the PACU?

You will likely feel some pain as the anesthesia wears off, but the nursing staff will give you pain medication to keep you comfortable. Many people also receive a nerve block before surgery, which numbs the knee for several hours after you wake up. This means you may feel little to no pain in the when ready recovery period.

How soon after surgery can I go home?

If you are having outpatient surgery, you will go home four to six hours after arriving at the facility, once you are alert and your pain is controlled. If you are staying overnight, you will be discharged the next morning. Either way, you must have someone drive you — you cannot drive yourself the day of surgery.