Knee replacement surgery typically lasts 1 to 2 hours in the operating room

The actual surgical procedure — from the moment you are asleep until the surgeon closes the incision — usually takes between 60 and 120 minutes. A straightforward first-time knee replacement on a patient with no complications often runs closer to 90 minutes. If you have had previous knee surgery, arthritis that has damaged bone more severely, or other medical conditions, the procedure may take longer.

The total time you spend in the surgical facility is much longer than the surgery itself. You will arrive 1 to 2 hours before the procedure for check-in, bloodwork, and anesthesia preparation. After surgery, you will spend 1 to 3 hours in the recovery room before moving to a regular hospital bed or being discharged home, depending on whether your surgery is inpatient or outpatient.

Key Takeaways

  • The surgeon spends 1 to 2 hours on the actual replacement, but you will be at the facility for 4 to 6 hours total on surgery day.
  • Outpatient knee replacements (same-day discharge) are now common and take the same surgical time as inpatient procedures.
  • Previous knee surgery, severe arthritis, or bone damage can add 30 minutes to an hour to the operating room time.
  • Anesthesia type — general, spinal, or regional nerve block — does not significantly change how long the surgery takes, but affects how you feel afterward.

What happens during those 1 to 2 hours

The surgeon makes an incision over 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), and shape the remaining bone to fit the artificial joint components. This preparation work takes the majority of the surgical time.

Once the bone surfaces are ready, the surgeon cements or presses the metal and plastic components into place. They test the knee's range of motion and alignment to may support it moves smoothly and bears weight evenly. The final 15 to 20 minutes are spent closing the incision with stitches or staples and explore a sterile dressing.

Why some surgeries take longer than others

A patient with severe arthritis or bone loss may require the surgeon to use bone grafts or thicker implant components, which adds time. Previous knee surgery — such as an ACL repair or meniscus removal — can make it harder to access the joint and remove scar tissue, extending the procedure by 30 minutes or more.

Obesity, diabetes, or other medical conditions can slow the procedure slightly because the surgeon must work more carefully through thicker tissue or take extra precautions to prevent infection. A surgeon's experience and the specific implant system being used also play a role; some newer implant designs are engineered for faster placement.

Anesthesia and its effect on your timeline

Most knee replacements use either general anesthesia (you are completely asleep) or spinal anesthesia (you are awake but numb from the waist down). Some surgeons use a regional nerve block, which numbs only the leg. The type of anesthesia does not change how long the surgery takes, but it does affect how long you stay in recovery.

With general anesthesia, you may spend 1 to 2 hours waking up and being monitored. Spinal anesthesia typically means a shorter recovery period — 30 minutes to 1 hour — because you do not need time to regain consciousness. Your anesthesiologist will discuss which option is safest for your medical history.

Same-day discharge versus overnight hospital stay

Outpatient knee replacements, where you go home the same day, have become increasingly common. The surgery itself takes the same 1 to 2 hours whether you stay overnight or not. The difference is in what happens after: outpatient patients spend 2 to 3 hours in recovery and must meet specific criteria (stable vital signs, ability to bend and straighten the knee, a responsible adult to drive them home) before discharge.

Inpatient procedures involve an overnight stay, which gives you time to begin physical therapy and have nursing staff monitor your pain and swelling. Your surgeon will recommend one approach or the other based on your age, overall health, home support, and the complexity of your case.

What to expect on surgery day

Plan to arrive at the surgical facility 60 to 90 minutes before your scheduled procedure time. You will check in, change into a surgical gown, and have an IV placed. A nurse will review your medical history and medications, and the anesthesiologist will meet with you to discuss the anesthesia plan.

You will then be taken to the operating room, where the surgical team will position you on the table and begin anesthesia. The actual surgery follows. Once the surgeon finishes, you will be moved to the recovery room, where nurses will monitor your heart rate, blood pressure, oxygen level, and pain. If you are having outpatient surgery, you will be discharged once you meet the criteria above. If you are staying overnight, you will be moved to a hospital room for continued monitoring and the start of physical therapy.

Recovery timeline after you leave the operating room

The first 24 to 48 hours after surgery are the most critical for managing pain and swelling. You will be given pain medication and ice, and your leg will be elevated. Physical therapy typically begins within hours of surgery, even on the day of the procedure, with straightforward movements like bending and straightening the knee.

If you are discharged the same day, you will go home with crutches or a walker, pain medication, and instructions for icing and elevation. If you stayed overnight, you will likely spend 1 to 2 days in the hospital before discharge. Full recovery — returning to normal activities without pain or stiffness — typically takes 3 to 6 months, though some people continue improving for up to a year.

Frequently Asked Questions

Does the type of implant used change how long surgery takes?

Different implant systems have slightly different placement methods, but the difference is usually only 10 to 15 minutes. Newer implants designed for faster insertion may shorten the procedure slightly, but the surgeon's skill and your individual anatomy matter more than the brand of implant.

Will my surgery take longer if I am overweight?

Possibly. Obesity can add 15 to 30 minutes because the surgeon must work through thicker tissue and may need to take extra care to position the implant correctly. Your surgeon will discuss this during your pre-surgery consultation.

What if something goes wrong during surgery — does that add time?

Yes. If the surgeon discovers unexpected bone damage, infection, or other complications, the procedure may take significantly longer. This is rare, but your surgeon will communicate with your family if the surgery extends beyond the expected time.

Can I watch my surgery or get a video of it?

Most hospitals do not allow patients to watch their own surgery, but some surgeons record the procedure for educational purposes or to show you afterward. Ask your surgeon during your pre-surgery visit whether this is an option.

Is there a difference in surgery time between a partial and total knee replacement?

A partial knee replacement, which replaces only one compartment of the knee, typically takes 45 minutes to 1 hour — shorter than a total replacement. However, not all patients are candidates for a partial replacement; your surgeon will determine which procedure is right for your knee damage.