The operation itself takes one to three hours, depending on whether it's a standard replacement or a revision of an earlier surgery
A typical knee replacement operation lasts between 60 and 90 minutes once you're in the operating room. If you're having both knees replaced in one session, add another 30 to 60 minutes. A revision surgery—replacing a knee that was already replaced—usually takes longer, often two to three hours, because the surgeon has to remove the old implant and work around scar tissue.
The time in the operating room is only part of your day at the hospital or surgical center. You'll arrive early for pre-operative checks, spend time in recovery after anesthesia wears off, and may stay overnight or go home the same day depending on your surgeon's approach and your overall health. The entire process from arrival to discharge typically spans 4 to 8 hours.
Key Takeaways
- The actual surgery takes 60 to 90 minutes for a standard knee replacement, longer if both knees are done or if it's a revision of an earlier surgery.
- You'll spend additional time in pre-operative preparation and post-operative recovery, making the full day at the facility 4 to 8 hours.
- General anesthesia means you'll be unconscious during surgery and need recovery time before you can go home or to a hospital room.
- Your surgeon will discuss the expected timeline during your pre-operative consultation, and this can vary based on your anatomy and any complications found during surgery.
What happens before the surgeon starts
You'll arrive at the surgical facility 1 to 2 hours before your scheduled operation time. During this window, nursing staff will check your vital signs, review your medical history one more time, place an IV line, and have you change into a surgical gown. An anesthesiologist will meet with you to discuss the anesthesia plan and answer any last-minute questions.
You may also receive a regional nerve block—an injection near your knee that numbs the area—in addition to general anesthesia. This reduces pain after surgery and can lower the amount of pain medication you need. The nerve block itself takes 10 to 15 minutes and happens before you go into the operating room.
Inside the operating room: what takes the time
Once anesthesia takes effect, the surgeon begins by making an incision, usually 8 to 10 inches long, over the front of your knee. Preparing the bone surfaces—removing damaged cartilage and bone and shaping the ends to fit the implant—takes the bulk of the surgery time. This is precise work that cannot be rushed.
The surgeon then positions the metal and plastic components, tests the knee's range of motion and alignment, and closes the incision in layers. If the surgery reveals unexpected damage or bone loss, the surgeon may need to use bone grafts or specialized implants, which adds time. Your surgeon will have discussed these possibilities beforehand.
Recovery in the hospital and going home
After surgery ends, you move to the recovery room (sometimes called post-anesthesia care) where nurses monitor you as the anesthesia wears off. This phase typically lasts 1 to 2 hours. You'll be groggy and may feel nauseous or cold—both normal responses to general anesthesia. Pain medication is given as needed.
Some surgeons use same-day discharge protocols, meaning you go home 2 to 4 hours after leaving the operating room, once you can walk with crutches and your vital signs are stable. Others prefer an overnight stay so you can begin physical therapy the next morning and have nursing support nearby. Your surgeon will explain which approach they use and what your specific plan will be.
Why the time varies from patient to patient
Your age, weight, bone quality, and the extent of arthritis damage all affect how long surgery takes. Patients with severe arthritis or bone loss may need extra time. Previous knee surgery, hardware from an old injury, or unusual anatomy can also extend the operation.
Complications found during surgery—such as unexpected bone damage or ligament issues—may require the surgeon to adjust the plan, which takes additional time. This is why surgeons schedule operating room time with a buffer and why your surgeon cannot always predict the exact minute the operation will end.
Timeline from start to finish: a typical day
| Stage | Typical Duration |
|---|---|
| Arrival and pre-operative prep | 1 to 2 hours |
| Anesthesia and nerve block (if used) | 15 to 30 minutes |
| Surgery itself | 60 to 90 minutes |
| Recovery room | 1 to 2 hours |
| Discharge or transfer to hospital room | 30 minutes to 1 hour |
| Total time at facility | 4 to 8 hours |
What to expect after you leave the operating room
Even though the surgery is finished, your body is still working hard. Pain, swelling, and stiffness are normal in the first few days. You'll take pain medication as prescribed and begin gentle movement exercises, often with a physical therapist, within hours of surgery.
Most people spend the first 1 to 2 weeks managing pain and swelling at home, using ice, elevation, and compression. Walking with crutches or a walker starts when ready. Full recovery—returning to normal activities without pain—typically takes 3 to 6 months, though some people continue improving for up to a year.
Frequently Asked Questions
Can I choose to have both knees done on the same day?
Yes, bilateral knee replacement (both knees at once) is an option some surgeons offer. It adds 30 to 60 minutes to the operating time and requires a longer recovery period, but it means only one anesthesia and one recovery process instead of two separate surgeries months apart. Your surgeon will discuss whether this is safe for you based on your age and overall health.
Will I be awake during the surgery?
No. You receive general anesthesia, which means you're unconscious for the entire operation. You won't feel pain or remember anything that happens in the operating room. Some surgeons also use a regional nerve block to numb the knee area, but this is done while you're already asleep.
What if the surgery takes longer than expected?
If complications arise—such as bone loss, ligament damage, or difficulty removing old hardware—the surgeon may need extra time. Your family will be updated if the operation runs significantly longer than planned. This is one reason surgeons ask you to have someone available to wait during the procedure.
How long will I be in pain after surgery?
Severe pain typically peaks in the first 24 to 48 hours and then gradually improves over the first 2 weeks. You'll take prescribed pain medication on a schedule during this time, not just when pain becomes unbearable. Most people transition to over-the-counter pain relief by week 3 or 4, though some soreness continues for several weeks.
When can I drive after knee replacement?
Most surgeons recommend waiting 4 to 6 weeks before driving, and only after you've stopped taking prescription pain medication and regained enough strength and range of motion to control the pedals safely. Check your surgeon's specific guidelines, as they vary based on your recovery progress and which knee was replaced.