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

Knee replacement, also called knee arthroplasty, involves removing damaged cartilage and bone from your knee joint and replacing it with artificial components made of metal and plastic. A surgeon makes an incision, typically 8 to 10 inches long, cuts through muscle and tissue to reach the joint, and then reshapes the bone surfaces to fit the prosthetic parts. The whole operation usually takes 1 to 2 hours under general anesthesia.

It is major surgery because it requires general anesthesia, involves significant tissue damage that takes weeks to heal, and demands a structured recovery period with physical therapy. However, it is also routine—orthopedic surgeons perform over 700,000 knee replacements annually in the United States, and the procedure has a long track record of success. Most people who have the surgery report substantial pain relief and improved mobility within 3 to 6 months.

Key Takeaways

  • Knee replacement requires general anesthesia and an incision of 8 to 10 inches, making it a major surgical procedure that typically lasts 1 to 2 hours.
  • Recovery involves a hospital stay of 1 to 3 days, followed by 6 to 12 weeks of physical therapy before you can return to normal activities.
  • Common risks include blood clots, infection, and stiffness, though serious complications occur in fewer than 2 percent of cases.
  • Most artificial knees last 15 to 20 years, meaning some people may need a second replacement later in life.
  • Your surgeon will review your medical history, current medications, and overall health to determine whether you are a suitable candidate.

What happens during the surgery itself

You will arrive at the hospital or surgical center several hours before your scheduled procedure. A nurse will place an IV line, and an anesthesiologist will discuss the type of anesthesia—usually general anesthesia, which means you will be unconscious throughout. Some surgeons also use a regional block (numbing medication around the nerves of your leg) in addition to general anesthesia to reduce pain afterward.

Once you are asleep, the surgeon makes an incision down the front of your knee, typically 8 to 10 inches long. They move the muscles and tissues aside to expose the joint, then use specialized instruments to remove the damaged cartilage and bone. The surgeon then positions the metal components (femoral and tibial implants) and secures them with bone cement or a press-fit technique. A plastic spacer is inserted between the metal parts to act as a new cartilage surface. The incision is closed with stitches or staples, and you are moved to recovery.

Hospital stay and when ready recovery

Most people stay in the hospital for 1 to 3 days after knee replacement, though some go home the same day depending on their health and the surgeon's preference. Before you leave, a physical therapist will teach you basic exercises—usually gentle knee bends and straight-leg raises—to prevent blood clots and begin regaining motion. You will also receive instructions on wound care, pain management, and when to call your surgeon.

Pain and swelling are normal and peak around day 3 to 5 after surgery. Your surgeon will prescribe pain medication, and you will use ice and elevation to manage swelling. Most people use crutches or a walker for the first 2 to 4 weeks. You cannot drive while taking prescription pain medication, so arrange transportation in advance. Stitches or staples are typically removed 10 to 14 days after surgery.

Physical therapy and returning to activity

Physical therapy begins within days of surgery and continues for 6 to 12 weeks. A physical therapist will guide you through exercises designed to restore your knee's range of motion and strengthen the muscles around it. Early on, the focus is on preventing stiffness and regaining the ability to straighten and bend your knee. As healing progresses, exercises become more challenging and functional—walking longer distances, climbing stairs, and eventually returning to hobbies.

Most people can return to light activities like walking and desk work within 4 to 6 weeks. Returning to higher-impact activities like hiking, tennis, or running typically takes 3 to 6 months. Your surgeon and physical therapist will give you specific guidance based on your progress. Skipping physical therapy or stopping too early is one of the most common reasons people experience stiffness or poor outcomes.

Risks and complications to understand

Serious complications from knee replacement are uncommon, occurring in fewer than 2 percent of cases. The most frequent risks include blood clots in the leg (deep vein thrombosis), infection, and stiffness if you do not do physical therapy. Blood clots can be prevented with compression stockings, leg exercises, and sometimes blood-thinning medication. Infection is rare because surgery is performed in a sterile operating room, but if it occurs, antibiotics or additional surgery may be needed.

Other possible complications include nerve or blood vessel injury, implant loosening over time, and persistent pain or swelling. Implant loosening is not when ready—it typically develops years after surgery if it happens at all. Allergic reactions to the implant materials are extremely rare. Your surgeon will discuss your individual risk factors based on your age, weight, overall health, and medical history.

How long artificial knees last

Most modern knee implants last 15 to 20 years, though some last longer and some wear out sooner depending on your activity level and body weight. Younger patients who are very active may experience implant wear faster than older, less active patients. If your implant does wear out or loosen, revision surgery (replacing the original implant) is possible, though it is more complex and has a longer recovery than the first replacement.

This is an important consideration if you are having knee replacement in your 50s or 60s—you may eventually need a second procedure. Your surgeon can discuss the longevity data for the specific implant they plan to use and help you understand the timeline.

Before surgery: what your surgeon needs to know

Your surgeon will review your complete medical history, including heart disease, diabetes, blood clots, and any previous surgeries. Tell them about all medications and supplements you take, including blood thinners, aspirin, and herbal products. Some medications need to be stopped before surgery, while others must be continued. Your surgeon may order blood tests, an EKG, or a chest X-ray to make sure you are healthy enough for surgery.

If you smoke, your surgeon will strongly encourage you to stop at least 2 to 4 weeks before surgery, as smoking slows healing and increases infection risk. If you are overweight, losing even a small amount of weight before surgery can reduce stress on your new knee and improve outcomes. If you have sleep apnea or other breathing problems, tell your anesthesiologist, as this affects how they manage your anesthesia.

Preparing your home and life for recovery

Before surgery, set up your home to make recovery easier. Arrange your bedroom and bathroom on one level if possible, or set up a temporary sleeping area downstairs to avoid stairs in the first few weeks. Install grab bars in the bathroom, remove throw rugs that could cause tripping, and make sure pathways are clear. Stock your freezer with straightforward meals, arrange for someone to help with household tasks, and plan for transportation to physical therapy appointments.

Ask your surgeon when you can shower (usually after stitches are removed), when you can return to driving (typically 4 to 6 weeks if you are off prescription pain medication), and when you can return to work. If your job involves standing or walking all day, you may need more time off than someone with a desk job. Having these answers before surgery helps you plan realistically.

Frequently Asked Questions

Will I be able to walk normally after knee replacement?

Most people walk normally without a limp within 3 to 6 months. Some people notice a slight difference in how their knee feels compared to their natural knee, but this usually becomes less noticeable over time. Walking is one of the best activities for your new knee and is strongly encouraged during recovery.

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 health. However, this means a longer surgery, longer anesthesia time, and a more demanding recovery. Many surgeons prefer to do one knee at a time, spacing them several months apart, so you can recover and regain strength between procedures.

What activities should I avoid after knee replacement?

You should avoid high-impact activities like running, jumping, and contact sports indefinitely, as these can wear out your implant faster. Low-impact activities like walking, swimming, cycling, and golf are generally safe once you have recovered. Your surgeon will give you specific guidance based on your implant type and your individual situation.

How much pain should I expect after surgery?

Pain is normal and expected, especially in the first 2 to 4 weeks. Your surgeon will prescribe pain medication to manage it. Most people describe the pain as manageable with medication rather than severe. Pain that is not controlled by your prescribed medication, or pain that suddenly gets worse after improving, should be reported to your surgeon when ready.

Will I need to take blood thinners after surgery?

Your surgeon may prescribe blood-thinning medication for 10 to 35 days after surgery to reduce the risk of blood clots. This depends on your individual risk factors and your surgeon's protocol. You will receive clear instructions on how long to take the medication and what to watch for, such as unusual bruising or bleeding.