Yes, knee replacement is major surgery, but it's one of the most common and well-established procedures in orthopedics

Knee replacement—formally called knee arthroplasty—involves removing damaged bone and cartilage from your knee joint and replacing it with metal and plastic components. A surgeon makes an incision, typically 8 to 10 inches long, cuts through muscle and tissue to reach the joint, and then uses specialized instruments to reshape the ends of your thighbone and shinbone. The artificial joint is then cemented or press-fit into place. Because it requires general or regional anesthesia, involves opening the joint, and demands weeks of recovery, it meets the medical definition of major surgery.

That said, the procedure has been performed hundreds of thousands of times per year in the United States alone, and complication rates are low when done by an experienced surgeon in a proper facility. Understanding what "major" means in practical terms—what happens in the operating room, what your body goes through, and what recovery actually looks like—helps you prepare realistically.

Key Takeaways

  • Knee replacement requires general or regional anesthesia and an incision into the joint, making it major surgery by medical standards.
  • The procedure typically lasts 1 to 2 hours, and you will spend several hours in recovery before going home or to a hospital bed.
  • Most people spend 1 to 3 nights in the hospital, though some facilities now offer same-day discharge with strict home support requirements.
  • Physical therapy begins within 24 hours and continues for weeks; your effort during this phase directly affects how well your knee functions long-term.
  • Serious complications like blood clots or infection occur in fewer than 2 percent of cases, but knowing the warning signs matters.

What happens during the surgery itself

You will arrive at the surgical center or hospital 1 to 2 hours before your scheduled time. An anesthesiologist will place an IV line and discuss which type of anesthesia you will receive—usually general anesthesia (you are unconscious) or a spinal block (you are awake but numb from the waist down). Most people prefer not to remember the procedure, so general anesthesia is common.

Once you are under anesthesia, the surgeon makes an incision down the front of your knee, typically 8 to 10 inches long. They move the kneecap to the side and remove the damaged cartilage and bone from the ends of your thighbone and shinbone using specialized cutting guides. The artificial components—usually made of metal (cobalt-chromium or titanium) and plastic (polyethylene)—are then positioned and secured. Some surgeons use cement; others rely on a press-fit technique where the implant is shaped to grip the bone directly. The incision is closed with stitches or staples.

The entire procedure takes 1 to 2 hours. You then spend 1 to 3 hours in the recovery room while anesthesia wears off and nurses monitor your vital signs, pain level, and how well your leg is moving.

Hospital stay and when ready recovery

Most patients stay in the hospital for 1 to 3 nights after knee replacement. Some facilities now offer same-day discharge, but this requires a responsible adult at home, a ground-floor bedroom or accessible bathroom, and the ability to attend physical therapy the next day. If you live alone or have limited home support, a hospital stay or short-term rehabilitation facility may be necessary.

During your hospital stay, nurses will help you manage pain with medication, monitor the surgical site for signs of infection, and help you move your leg and walk with a walker or crutches. Physical therapy typically begins within 24 hours—sometimes the same day. A therapist will help you bend and straighten your knee, teach you how to use assistive devices safely, and show you exercises to prevent blood clots.

You will wear compression stockings or use a sequential compression device (a sleeve that inflates and deflates around your calf) to reduce the risk of deep vein thrombosis (DVT), a blood clot in the leg. You may also receive blood-thinning medication by injection or mouth. Pain is managed with a combination of medications: opioids (if needed), non-steroidal anti-inflammatory drugs like ibuprofen, and sometimes nerve blocks or epidural catheters that deliver medication directly to the surgical area.

The first 6 weeks at home

Once you leave the hospital, recovery is not passive. You will attend physical therapy 2 to 3 times per week for 6 to 12 weeks, and you must do prescribed exercises at home on the days you don't have a session. The goal is to regain range of motion (bending and straightening the knee) and rebuild strength in the muscles around the joint.

Pain and swelling are normal and can last several weeks. You will ice the knee, elevate your leg, and take pain medication as prescribed. Most people can put weight on the leg within a few days and walk with crutches or a walker. By 4 to 6 weeks, many people transition to walking with a cane or without information, though this varies widely.

You cannot drive while taking opioid pain medication or while your leg is immobilized, so plan for someone to drive you to appointments. You also cannot return to work if your job requires standing, walking, or driving—this typically takes 6 to 12 weeks depending on your job and how your recovery progresses.

Common complications and warning signs

Serious complications occur in fewer than 2 percent of knee replacements, but knowing what to watch for matters. Blood clots (DVT or pulmonary embolism) are the most common serious complication. Signs include sudden swelling in the calf, warmth, redness, or sharp chest pain and shortness of breath. Infection at the surgical site can develop days or weeks after surgery; watch for increasing redness, warmth, drainage, fever, or spreading redness. Stiffness can occur if you do not do physical therapy consistently—this is why your effort in the first weeks is critical.

Less serious but common issues include temporary numbness around the incision (usually resolves over months), persistent swelling, and difficulty sleeping due to pain. Call your surgeon when ready if you develop signs of infection, chest pain, severe shortness of breath, or a calf that is suddenly much larger than the other leg.

Long-term recovery and return to normal activity

Most people feel significantly better by 3 to 6 months, though full recovery can take up to a year. By 6 months, many people can walk without a cane, climb stairs, and return to low-impact activities like swimming, cycling, or golf. High-impact activities like running or jumping are generally not recommended, as they can wear out the artificial joint faster.

Your artificial knee will likely last 15 to 20 years, though this varies based on your age, weight, activity level, and the specific implant used. Younger patients may eventually need a revision surgery (replacement of the artificial joint), while older patients often have the original implant for life.

You will have follow-up appointments with your surgeon at 2 weeks, 6 weeks, 3 months, and sometimes 1 year. X-rays may be taken to confirm the implant is positioned correctly and not shifting. After that, annual check-ups are typical, though some surgeons see patients less frequently if everything is stable.

Preparing your home and support system

Before surgery, prepare your home so you can move safely with limited mobility. Install grab bars in the bathroom, remove throw rugs that could cause tripping, and arrange frequently used items at waist height so you don't have to bend or reach. If your bedroom or bathroom is upstairs, plan to sleep and use the bathroom on the ground floor for the first few weeks.

Arrange for someone to help you for at least the first 1 to 2 weeks—someone who can help with cooking, cleaning, laundry, and getting to physical therapy appointments. If you live alone, discuss this with your surgeon before surgery; some facilities can arrange temporary home care or recommend a rehabilitation center.

Frequently Asked Questions

Can I have both knees replaced at the same time?

Some surgeons will replace both knees in one surgery if both are severely damaged and you are in good overall health. However, this increases the stress on your body and the risk of complications. Most surgeons prefer to do one knee at a time, spacing them 3 to 6 months apart so you can recover and regain strength between procedures.

Will I set off metal detectors after knee replacement?

Modern knee implants are made of materials that typically do not trigger standard metal detectors at airports or security checkpoints. However, some implants do contain metal, so ask your surgeon for an implant card to carry with you. If you do trigger a detector, show the card and you will usually be allowed to proceed with a pat-down instead of additional screening.

How much pain should I expect after surgery?

Pain is normal and expected, especially in the first 2 to 4 weeks. Most people describe it as soreness and stiffness rather than sharp pain. Your surgeon will prescribe pain medication, and you should take it as directed—waiting until pain is severe makes it harder to control. By 6 to 8 weeks, most people need over-the-counter pain relief only occasionally.

What if I don't do physical therapy?

Your knee will likely become stiff and weak, and you may never regain full range of motion or the ability to walk normally. Physical therapy is not optional; it is the most important part of recovery. Even if it is uncomfortable, doing the exercises consistently in the first weeks directly determines how well your knee functions months and years later.

Can I kneel after knee replacement?

Many people can kneel on the replaced knee after full recovery, though some find it uncomfortable due to pressure on the scar or the artificial joint. It depends on your pain tolerance and how well your tissues heal. Ask your surgeon during follow-up visits whether kneeling is safe for your specific implant and situation.