A total knee replacement removes the damaged surfaces of your knee joint and replaces them with artificial parts

A total knee replacement, often called a TKR or total knee arthroplasty, is surgery to remove the worn cartilage and bone from your knee joint and install artificial components in their place. The surgeon removes the damaged ends of your thighbone and shinbone, along with the kneecap surface, then attaches metal and plastic implants that recreate the shape of a healthy knee. The procedure takes roughly one to two hours and is performed under general anesthesia or spinal anesthesia, meaning you are asleep or numb from the waist down during the operation.

Most people have this surgery because arthritis has worn away the cartilage that normally cushions the knee joint, causing pain, stiffness, and difficulty walking or climbing stairs. Severe injury, bone tumors, or failed previous knee surgery can also lead to total knee replacement. The surgery is common — hospitals perform hundreds of thousands of them each year in the United States — and the implants are designed to last 15 to 20 years or longer with normal use.

Key Takeaways

  • Total knee replacement removes damaged bone and cartilage from your knee joint and replaces them with metal and plastic implants that mimic a healthy knee.
  • The surgery typically takes one to two hours and requires general or spinal anesthesia, so you will be asleep or numb during the procedure.
  • Most people undergo this surgery because severe arthritis has worn away the cartilage cushioning the knee, causing chronic pain and loss of function.
  • Recovery takes several months, with physical therapy starting within days of surgery and most people returning to light activities within six to twelve weeks.
  • Implants generally last 15 to 20 years, though the lifespan depends on your activity level, body weight, and how well you follow post-surgery care.

Why surgeons recommend total knee replacement

Your doctor will typically suggest total knee replacement only after other treatments have failed to relieve your pain. Before surgery, you may try anti-inflammatory medications, corticosteroid injections, physical therapy, or weight loss to reduce stress on the joint. If those steps do not reduce your symptoms enough to let you walk, climb stairs, or sleep without significant pain, surgery becomes a reasonable option.

Severe osteoarthritis is the most common reason for the procedure. In osteoarthritis, the smooth cartilage that covers the ends of your bones gradually wears away, leaving bone rubbing against bone. Rheumatoid arthritis, a disease where your immune system attacks joint tissue, can also damage the knee severely enough to require replacement. Traumatic injury — a fracture or ligament tear that heals poorly — may damage the joint surface in ways that lead to early arthritis and eventual replacement.

Your surgeon will review X-rays and possibly an MRI to confirm that the damage is severe and widespread enough to justify surgery. They will also check your overall health, your medications, and your ability to participate in physical therapy after surgery, since recovery requires active effort on your part.

What the surgical procedure involves

On the day of surgery, you will receive anesthesia to make you unconscious or numb from the waist down. The surgeon makes an incision down the front of your knee, usually 8 to 10 inches long, to access the joint. They then remove the damaged cartilage and bone from the ends of your thighbone and shinbone using specialized cutting guides that may support the implants will sit at the correct angle.

Next, the surgeon cements or presses metal components onto the prepared bone surfaces — typically a metal cap for the thighbone, a metal and plastic component for the shinbone, and a plastic button for the underside of the kneecap. Some surgeons use bone cement to hold the implants in place; others use a press-fit technique where the implants are held by friction and bone growth. The choice depends on your age, bone quality, and the surgeon's preference.

Once the implants are find, the surgeon tests the knee's range of motion and alignment, then closes the incision with stitches or staples. You will spend one to three hours in the recovery room as the anesthesia wears off, and most people go home the same day or stay overnight. Pain and swelling are normal in the first few days and weeks.

Recovery and physical therapy after surgery

Physical therapy begins within one to three days of surgery, even while you are still in the hospital or at home. A physical therapist will teach you exercises to reduce swelling, restore your knee's range of motion, and rebuild the strength in your leg muscles. Early movement is critical — your knee will be stiff and painful if you do not move it regularly, and scar tissue can form and limit your motion permanently.

Most people use crutches or a walker for the first two to six weeks after surgery. You will gradually put more weight on your leg as pain and swelling decrease and your muscles grow stronger. By six to twelve weeks, many people can walk without information and return to light activities like shopping or short walks. Full recovery, including return to more demanding activities, typically takes three to six months.

Swelling often persists for several months after surgery. Elevating your leg, explore ice, and wearing compression stockings can help manage it. Your surgeon will prescribe pain medication for the first few weeks and may recommend blood thinners to prevent clots, a rare but serious complication after knee surgery.

How long artificial knee implants last

Modern knee implants are built to last 15 to 20 years on average, and many last longer. The lifespan depends on several factors: your age at surgery, your weight, how active you are, and how well you follow your surgeon's restrictions on high-impact activities. Younger, more active patients may wear out an implant faster than older, less active ones.

Your surgeon will likely advise you to avoid high-impact activities like running, jumping, or contact sports after knee replacement. Walking, swimming, cycling, and golf are generally considered safe. Excess weight puts additional stress on the implant, so maintaining a healthy weight helps extend its life.

If an implant does wear out or fail, revision surgery — replacing the original implant with a new one — is possible but more complex and carries higher risks than the first surgery. For this reason, surgeons sometimes recommend waiting until later in life to have a total knee replacement if you are young and your pain can be managed with other treatments.

Risks and complications

Total knee replacement is generally safe, but like any surgery it carries risks. Infection occurs in fewer than 2 percent of cases and is usually treated with antibiotics, though severe infections may require additional surgery. Blood clots can form in the legs after surgery; your surgeon may prescribe blood thinners or recommend compression stockings to reduce this risk.

Stiffness is common in the weeks after surgery but usually improves with physical therapy. Persistent stiffness affecting your range of motion is less common but can occur if you do not do your exercises or if scar tissue forms. Implant loosening, wear, or breakage can happen over time, particularly if you are very active or if the implant was not positioned correctly during surgery.

Nerve or blood vessel injury during surgery is rare but possible. You may experience numbness or tingling around the incision, which often improves over time. Chronic pain after surgery affects a small percentage of patients and can be difficult to treat; your surgeon should discuss this possibility before you decide to have the procedure.

Preparing for total knee replacement

Before surgery, your surgeon will order blood tests and possibly an EKG or chest X-ray to make sure you are healthy enough for anesthesia and surgery. Tell your surgeon about all medications you take, including blood thinners, since some must be stopped before surgery. Arrange for someone to drive you home and help you for the first few days, since you will not be able to drive or live independently when ready after surgery.

Prepare your home before surgery: place frequently used items at waist height so you do not have to bend or reach, install grab bars in the bathroom, and remove tripping hazards like throw rugs. If you have stairs, practice using crutches on them before surgery, or plan to sleep on a lower floor temporarily. Some people rent a walker or shower chair to make daily tasks easier during early recovery.

Your surgeon may recommend losing weight before surgery if you are overweight, since excess weight increases stress on the implant and can complicate recovery. Even a modest weight loss can improve your results and reduce your risk of complications.

Frequently Asked Questions

How much pain will I have after total knee replacement?

Pain is usually most severe in the first few days and weeks after surgery, then gradually decreases over several months. Your surgeon will prescribe pain medication to manage it, and ice, elevation, and compression also help. Most people report that post-surgery pain is less severe than the chronic pain they had before surgery, and it improves steadily with physical therapy and time.

Can I return to sports or exercise after knee replacement?

Low-impact activities like walking, swimming, cycling, and golf are generally safe after knee replacement. High-impact activities like running, jumping, or contact sports are usually not recommended because they can wear out the implant faster. Ask your surgeon which specific activities are safe for you based on your age, activity level, and the type of implant used.

What happens if my knee implant fails or wears out?

If your implant fails or wears out after many years, revision surgery can replace it with a new implant. Revision surgery is more complex than the original procedure and carries higher risks, so it is typically reserved for cases where the implant is clearly damaged or causing significant problems. This is one reason surgeons sometimes recommend waiting to have knee replacement if you are young.

Will I set off metal detectors after knee replacement?

Most modern knee implants contain metal and may trigger metal detectors at airports or security checkpoints. Your surgeon will give you an implant card listing the type and manufacturer of your implant. Show this card to security personnel, and they can usually clear you without additional screening or allow a pat-down search instead.

How soon can I drive after knee replacement?

Most surgeons recommend waiting four to six weeks before driving, depending on which knee was replaced and when you can safely stop taking narcotic pain medication. If your right knee was replaced, you may need to wait longer since you need good control of that leg to operate the brake and accelerator. Check with your surgeon before getting behind the wheel.