Yes, knee replacement is major surgery, but it is 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 artificial components made of metal and plastic. The 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 bone surfaces and fit the prosthetic parts. The entire operation usually takes 1 to 2 hours.

It is classified as major surgery because it requires general or regional anesthesia, involves significant tissue trauma, and demands a structured recovery period. However, the classification does not mean it is rare or experimental. Orthopedic surgeons in the United States perform over 700,000 knee replacements annually, and the procedure has a well-documented track record spanning decades. Most people who have the surgery experience meaningful pain relief and restored function, though recovery requires commitment to physical therapy and activity restrictions for several months.

Key Takeaways

  • Knee replacement requires general or regional anesthesia and involves an 8 to 10 inch incision to remove damaged joint surfaces and install artificial components.
  • The surgery itself takes 1 to 2 hours, but the full recovery period spans 3 to 6 months, with the most intensive physical therapy happening in the first 6 weeks.
  • Serious complications such as blood clots, infection, or implant failure occur in fewer than 2 percent of cases, but minor complications like swelling and stiffness are common in the first weeks.
  • Your surgeon will want to know about all medications you take, any bleeding disorders, and whether you have had previous knee surgery, as these factors affect how the operation is planned.
  • Most artificial knees last 15 to 20 years, meaning some people may need a second replacement (called revision surgery) later in life.

What happens during the operation

You will arrive at the surgical center or hospital 1 to 2 hours before your scheduled time. A nurse will place an IV line, and an anesthesiologist will discuss which type of anesthesia you will receive—usually general anesthesia (you are asleep) or a spinal block (you are awake but numb from the waist down). Most people receive a nerve block as well, which numbs the leg and reduces pain for the first 24 hours after surgery.

Once you are anesthetized, the surgeon makes an incision down the front of the knee, typically 8 to 10 inches long. They move the kneecap to the side and remove the damaged cartilage and bone from the femur (thighbone) and tibia (shinbone). Using alignment guides and specialized cutting instruments, they shape the bone surfaces to match the artificial components. The surgeon then cements or press-fits the metal and plastic pieces into place, tests the knee's movement and stability, and closes the incision with stitches or staples.

You will spend 1 to 2 hours in the recovery room while the anesthesia wears off. Most people go home the same day or stay overnight; hospital stays longer than one night are now uncommon unless you have other health conditions that require monitoring.

Pain and swelling in the first weeks

The first 2 weeks after surgery are the most uncomfortable. Your knee will be swollen, bruised, and painful, even with prescription pain medication. You will wear a compression bandage or sleeve and may use ice packs for 15 to 20 minutes several times a day to reduce swelling. Elevating your leg above heart level when sitting or lying down also helps.

Pain medication prescribed after surgery typically includes opioids for the first few days, then transitions to over-the-counter options like acetaminophen or ibuprofen as pain decreases. Some surgeons also recommend nerve pain medication if you experience tingling or burning sensations. You will likely need pain relief for 4 to 6 weeks, though the intensity should drop noticeably after the first 2 weeks.

Swelling can persist for 3 to 6 months, and some people report that their knee feels stiff or warm to the touch for weeks. This is normal and does not indicate a problem. However, if you develop severe redness, warmth, drainage from the incision, or fever above 101 degrees Fahrenheit, contact your surgeon when ready, as these can signal infection.

Physical therapy and movement restrictions

Physical therapy begins within 24 hours of surgery, often while you are still in the hospital or recovery center. A physical therapist will teach you exercises to restore range of motion and strength. In the first week, these are gentle movements: bending and straightening your knee, quadriceps sets (tightening the thigh muscle), and heel slides. By week 2 or 3, you will progress to standing exercises, walking with crutches or a walker, and light resistance work.

You will attend physical therapy sessions 2 to 3 times per week for 6 to 12 weeks. Between sessions, you will perform exercises at home—typically 30 to 45 minutes daily. This commitment is critical: people who skip therapy or do not do home exercises often experience stiffness and reduced function. Your surgeon will set specific goals, such as achieving 90 degrees of knee bend by week 6 and 110 degrees by week 12.

For the first 6 weeks, you will use crutches or a walker and avoid putting full weight on the surgical leg. After 6 weeks, most people can walk without assistive devices, though some use a cane for balance. You should avoid high-impact activities—running, jumping, contact sports—indefinitely, as these can damage the artificial joint. Low-impact activities such as walking, swimming, cycling, and golf are generally safe once you have regained strength and range of motion, usually by 3 to 6 months.

Complications and how often they occur

Serious complications are uncommon but possible. Blood clots in the leg (deep vein thrombosis) occur in fewer than 2 percent of cases; your surgeon may prescribe blood-thinning medication or recommend compression stockings to reduce this risk. Infection of the surgical site happens in fewer than 1 percent of cases and is usually treated with antibiotics if caught early. Implant loosening or wear can occur years after surgery, sometimes requiring revision surgery (a second operation to replace the artificial components).

Minor complications are more common. Stiffness, where the knee does not bend as far as expected, affects some people and may require manipulation under anesthesia (a procedure where the surgeon gently forces the knee to bend while you are sedated) if physical therapy does not resolve it. Persistent swelling, minor nerve irritation causing numbness or tingling around the incision, and difficulty sleeping due to pain are also reported but usually improve over weeks to months.

Allergic reactions to the materials in the implant are rare but possible; discuss any metal allergies with your surgeon before surgery. Some people experience a feeling that the knee is unstable or "giving way," which usually resolves as strength returns. If you develop sudden severe pain, inability to move the knee, or signs of infection, seek when ready medical attention.

Recovery timeline and return to normal activities

The first 6 weeks are the most demanding. You will be managing pain, attending physical therapy multiple times per week, and learning to walk again. By week 6, most people can walk without crutches and perform basic daily activities like bathing, dressing, and light cooking, though you may still need help with stairs or heavy tasks.

By 3 months, you should have good pain control, significant improvement in range of motion, and the ability to walk for 20 to 30 minutes without difficulty. You can usually return to driving once you have stopped taking opioid pain medication and have regained enough strength and range of motion to operate the pedals safely—typically 4 to 6 weeks after surgery, though this varies by person and surgeon recommendation.

Full recovery takes 6 to 12 months. At the 6-month mark, most people report that their knee feels stable and strong, though some residual swelling or stiffness may remain. By 12 months, the artificial knee should feel like a normal part of your body, and you can participate in most activities you did before the surgery, with the exception of high-impact sports.

What your surgeon needs to know before the operation

Before scheduling surgery, inform your surgeon about all medications you take, including blood thinners, aspirin, and supplements. Some medications must be stopped before surgery; others must be continued. Tell your surgeon if you have diabetes, heart disease, lung disease, or a history of blood clots, as these conditions affect anesthesia planning and recovery.

Discuss any previous knee surgery, knee injuries, or problems with the opposite knee, as these can influence the surgical approach and implant selection. If you have a metal allergy or have had an allergic reaction to anesthesia in the past, mention it. Your surgeon will also want to know about your smoking status, alcohol use, and whether you live alone or have someone to help you during the first few weeks of recovery.

Bring a list of all your medications and supplements to your pre-surgery appointment, and ask your surgeon which ones to stop and when. Most surgeons schedule a pre-operative evaluation 1 to 2 weeks before surgery, where blood work and sometimes an EKG or chest X-ray are performed to may support you are healthy enough for anesthesia.

Artificial knee lifespan and revision surgery

Modern artificial knees are designed to last 15 to 20 years, though some last longer and some wear out sooner depending on your activity level, body weight, and the specific implant used. Younger people who have knee replacement may eventually need a second surgery (revision surgery) to replace the worn-out components. Revision surgery is more complex than the initial replacement because the surgeon must remove the old implant, which may have bonded to the bone, and then install new components.

Revision surgery carries higher risks of complications and typically requires a longer recovery period than the first replacement. For this reason, surgeons sometimes recommend that younger patients delay knee replacement as long as possible, using other treatments like physical therapy, injections, or activity modification to manage pain. Discuss your age, activity level, and long-term expectations with your surgeon when deciding whether to have the surgery now or wait.

Frequently Asked Questions

How long does the surgery take?

The operation itself usually takes 1 to 2 hours. You will spend additional time in pre-operative preparation (about 1 to 2 hours) and post-operative recovery (1 to 2 hours), so plan to be at the surgical facility for 4 to 6 hours total.

Will I need a blood transfusion?

Most knee replacements do not require a transfusion. Blood loss during the procedure is typically minimal. Your surgeon may discuss the option of donating your own blood before surgery (autologous donation) if you are at higher risk for needing transfusion, but this is uncommon for routine knee replacement.

Can I have both knees replaced at the same time?

Some surgeons will perform bilateral knee replacement (both knees in one surgery), but this is less common than doing them separately. Bilateral surgery reduces the total number of anesthesia exposures and recovery periods but increases the physical demands when ready after surgery. Discuss the pros and cons with your surgeon based on your age, overall health, and home support.

What if I am overweight or have other health problems?

Obesity and conditions like diabetes or heart disease increase surgical risk and may complicate recovery, but they do not automatically disqualify you from surgery. Your surgeon will evaluate your overall health and may recommend weight loss, better blood sugar control, or other preparations before scheduling. Some surgeons require a medical clearance from your primary care doctor or a cardiologist before proceeding.

How much does knee replacement cost?

The cost varies widely depending on your location, the hospital or surgical center, your insurance coverage, and whether complications arise. In the United States, the total cost (including surgeon fees, facility fees, anesthesia, and implant) typically ranges from $35,000 to $60,000 before insurance. If you have Medicare, it covers most of the cost after you meet your deductible. Contact your insurance company and the surgical facility to understand your out-of-pocket responsibility.