The surgery itself usually lasts one to three hours

A total knee replacement operation typically takes between 60 and 120 minutes from the moment the surgeon makes the first incision to the moment they close the wound. Most procedures fall in the 90-minute range. The exact time depends on your anatomy, the complexity of your knee damage, whether you have had previous knee surgery, and how quickly your body responds to anesthesia.

The surgeon spends most of this time removing the damaged cartilage and bone, positioning the metal and plastic implant components, and ensuring the knee moves smoothly through its full range of motion. Testing the fit and alignment takes significant time because even small misalignments can cause problems months or years later. If your surgeon discovers unexpected bone loss or damage during the operation, the procedure may run longer.

Key Takeaways

  • The actual surgery time is usually 60 to 120 minutes, but you will be at the hospital or surgical center for 4 to 6 hours total.
  • Anesthesia setup, positioning, and draping take 20 to 30 minutes before the surgeon begins, and closing takes another 15 to 20 minutes.
  • Previous knee surgery, bone loss, or arthritis affecting other parts of your knee can add 30 minutes or more to the operation.
  • Your surgeon will test the implant fit and alignment during the procedure, which is why rushing through this step is not an option.

What happens before the surgeon starts cutting

Before the actual surgery begins, you will spend 30 to 45 minutes in the pre-operative area. A nurse will check your vital signs, confirm your medical history, and insert an IV line. An anesthesiologist will review your health records and discuss which type of anesthesia you will receive — usually general anesthesia (you are fully asleep) or spinal anesthesia (you are awake but numb from the waist down).

Once you are in the operating room, another 20 to 30 minutes passes while the surgical team positions you on the table, applies monitoring equipment, administers anesthesia, and drapes your leg with sterile surgical sheets. The surgeon does not make the first incision until all of this is complete and the anesthesia team confirms you are ready.

The main steps and how long each takes

The surgeon follows a standard sequence, though timing varies based on what they find. First comes the incision and exposure — opening the skin and moving aside the muscles and tissues to reach the knee joint. This takes about 10 to 15 minutes. Next, the surgeon removes the damaged cartilage and bone from the femur (thighbone) and tibia (shinbone), which typically takes 20 to 30 minutes depending on how much bone is worn away.

Positioning and cementing the metal implant components takes another 20 to 30 minutes. The surgeon must align them precisely so your knee bends and straightens evenly. Testing the fit — moving the knee through its full range of motion, checking that it feels stable, and confirming the alignment — takes 15 to 20 minutes. This step cannot be rushed because poor alignment causes pain and implant failure years later. Finally, the surgeon closes the wound in layers, which takes 15 to 20 minutes.

Why some surgeries take longer than others

If you have had previous knee surgery, your surgeon will spend extra time removing scar tissue and working around any hardware that may still be in place. This can add 20 to 45 minutes. Severe arthritis that has damaged bone on multiple surfaces of the knee also extends the operation because the surgeon must remove more bone and may need to adjust the implant size or position.

Obesity, very stiff knees, or unusual bone anatomy can slow the surgeon's work. Some patients have bone loss so severe that the surgeon must use bone grafts or special implant components designed for missing bone, which adds time. If you have had a previous injury or fracture near the knee, the surgeon may encounter unexpected complications during the operation that require problem-solving.

Recovery room time and discharge

After the surgeon closes your wound, you move to the recovery room, where you spend 1 to 2 hours waking up from anesthesia and being monitored for any when ready complications. A nurse will check your pain level, blood pressure, heart rate, and oxygen levels regularly. You may feel groggy, nauseous, or cold — all normal responses to anesthesia.

Most patients go home the same day or stay overnight, depending on your age, overall health, and how well you are recovering. If you stay overnight, you will move to a hospital room where physical therapy begins the next morning. Total time from arrival to discharge is usually 4 to 6 hours for same-day surgery, or 20 to 24 hours if you stay overnight.

What to expect on surgery day

Arrive at the surgical facility 1 to 2 hours before your scheduled surgery time. You will be asked not to eat or drink after midnight the night before (your surgeon will give you exact instructions). Wear loose, comfortable clothing and leave jewelry, watches, and contact lenses at home. Bring your insurance card and photo ID.

Plan for someone to drive you home — you cannot drive yourself the day of surgery because anesthesia affects your judgment and reaction time for at least 24 hours. If you are staying overnight, bring a small bag with toiletries, comfortable clothes for going home, and any medications you take regularly. The surgical team will give you a detailed timeline when you arrive, but the entire process from check-in to discharge usually takes 4 to 6 hours.

Frequently Asked Questions

Can the surgery be done faster if the surgeon rushes?

No. Knee replacement requires precise alignment of the implant components, and rushing this step leads to pain, instability, and implant failure within a few years. A surgeon who finishes significantly faster than average may be cutting corners on alignment testing or component positioning, which is a red flag.

Does my age affect how long the surgery takes?

Age itself does not change the surgery time, but older patients may have more bone loss, previous surgeries, or other joint damage that complicates the procedure. Your surgeon can estimate your likely surgery time based on your X-rays and medical history before the operation.

What if my surgery takes much longer than expected?

Your surgeon will contact your family in the waiting room if the operation is running significantly longer than planned. Common reasons include unexpected bone loss, scar tissue from previous surgery, or the need for special implant components. Longer surgery time does not necessarily mean something went wrong — it usually means your surgeon is taking extra care to get the alignment right.

Will I be asleep the entire time?

If you receive general anesthesia, yes — you will be completely asleep. If you receive spinal anesthesia, you will be awake but cannot feel anything below your waist. Many surgeons offer spinal anesthesia because it has fewer side effects than general anesthesia, though you may hear sounds and feel pressure during the operation.

How long until I can walk after surgery?

Physical therapy begins the day of surgery or the next morning. Most patients walk with a walker or crutches within 24 hours. Full weight-bearing without assistive devices usually takes 4 to 6 weeks, and returning to normal activities takes 3 to 6 months.