A total knee replacement removes your damaged knee joint and replaces it with an artificial one

A total knee replacement (often called a TKR or total knee arthroplasty) is surgery where a surgeon removes the damaged surfaces of your knee bone and cartilage, then attaches artificial parts made of metal and plastic. The artificial joint mimics how your real knee moves. Most people have this surgery because arthritis has worn away the cartilage in their knee, causing pain and stiffness that doesn't improve with physical therapy, injections, or anti-inflammatory medication.

The surgery takes about one to two hours. You'll be under general anesthesia (asleep) or regional anesthesia (numb from the waist down). The surgeon makes an incision down the front of your knee, removes the damaged bone and cartilage, and cements or screws the artificial components into place. The artificial knee has three parts: a metal cap for the thighbone, a plastic spacer for the shinbone, and sometimes a plastic button for the kneecap.

Key Takeaways

  • Total knee replacement removes damaged cartilage and bone, then attaches artificial metal and plastic parts to restore knee movement.
  • Most people have this surgery because arthritis pain hasn't improved with physical therapy, medication, or injections.
  • Recovery takes three to six months for basic activities and up to a year for full strength and flexibility.
  • Physical therapy starts within days of surgery and continues for weeks or months to regain motion and strength.
  • Artificial knees typically last 15 to 20 years, though some last longer depending on your activity level and the implant design.

Why surgeons recommend total knee replacement

Your doctor will usually suggest this surgery only after other treatments have stopped working. Arthritis, injury, or bone disease can damage the smooth cartilage that lets your knee move without pain. When that cartilage wears away, bone rubs on bone, causing swelling, stiffness, and pain that gets worse with walking, stairs, or standing.

Before recommending surgery, your surgeon will have tried rest, ice, anti-inflammatory drugs like ibuprofen, physical therapy, weight loss if relevant, or injections of corticosteroids or hyaluronic acid into the joint. If you still can't walk, climb stairs, or sleep through the night because of knee pain after months of these treatments, you and your surgeon may decide surgery is worth the recovery time.

What happens before surgery

Your surgeon will order X-rays and possibly an MRI to see exactly how much damage is in your knee. You'll have blood tests and an EKG (heart test) to make sure you're healthy enough for surgery. Tell your surgeon about all medications you take, especially blood thinners like warfarin or aspirin—you may need to stop them before surgery.

A few weeks before surgery, you'll usually meet with a physical therapist who will show you exercises to do beforehand. Stronger muscles around your knee before surgery means faster recovery afterward. The night before surgery, you'll be told not to eat or drink anything after midnight. Plan for someone to drive you home and help you for the first few days, since you won't be able to put full weight on your leg right away.

The first weeks after surgery

You'll wake up with your leg wrapped in a compression bandage and possibly in a brace or splint. Pain and swelling are normal. You'll receive pain medication and blood thinners to prevent clots. Most people go home within one to three days, though some stay longer if they live alone or have other health problems.

Physical therapy begins within 24 to 48 hours—sometimes even before you leave the hospital. A therapist will help you bend and straighten your knee, walk with crutches or a walker, and do gentle exercises. This is uncomfortable but crucial; moving your knee prevents stiffness and blood clots. You'll ice your knee several times a day and keep your leg elevated to reduce swelling. Most people need pain medication for two to four weeks.

Recovery timeline and what to expect

The first six weeks are the most intense. You'll see your surgeon for follow-up visits, usually at two weeks and six weeks. By six weeks, most people can walk without a walker or crutches, though they may still limp. Swelling and stiffness often peak around two to three weeks, then gradually improve.

By three months, many people can return to light activities like walking, swimming, or stationary cycling. Full recovery—meaning normal strength, flexibility, and the ability to do stairs and light sports—usually takes six months to a year. Some people continue to improve for up to two years as scar tissue softens and muscles rebuild. Physical therapy typically continues for three to six months, though you'll do most exercises at home after the first few weeks.

How long an artificial knee lasts

Most artificial knees last 15 to 20 years. Some last longer; some wear out sooner depending on how active you are, your weight, and the quality of the implant. If your artificial knee wears out, you can have it replaced again, though revision surgery (replacing an artificial knee) is more complex than the first surgery and recovery takes longer.

Your surgeon will discuss activity restrictions with you. Most people can walk, swim, golf, and do low-impact exercise indefinitely. High-impact activities like running, jumping, or contact sports can wear out an artificial knee faster and are usually discouraged. Staying at a healthy weight and doing regular strengthening exercises help your artificial knee last longer.

Risks and complications

Like any surgery, total knee replacement carries risks. Blood clots in the leg are the most common serious complication, which is why you'll take blood thinners after surgery. Infection is rare but serious. Stiffness, where your knee won't bend as much as expected, happens to some people and may require additional physical therapy or even a second surgery. Some people have persistent pain or swelling that improves slowly over months.

Nerve or blood vessel injury during surgery is uncommon. Implant loosening or wear can happen years later. Your surgeon will discuss your individual risk based on your age, weight, other health conditions, and the reason for your surgery. Most people do well and are glad they had the surgery, but it's important to understand that recovery is gradual and requires effort on your part through physical therapy.

Frequently Asked Questions

Can I bend my knee after total knee replacement?

Yes, but it takes time. Right after surgery, bending is limited and uncomfortable. Physical therapy focuses on gradually increasing your bend. Most people reach 90 to 110 degrees of bend within three months. Full bend (120+ degrees) may take six months or longer. If your knee stays stiff, your therapist can work with you on deeper bending exercises.

Will I set off metal detectors with an artificial knee?

You may. Metal detectors at airports and security checkpoints sometimes react to the metal in artificial joints. You'll receive a card from your surgeon stating you have an implant. Show this at security; they can hand-check you instead of using the metal detector. Some newer implants are less likely to trigger detectors, so ask your surgeon about this if you travel frequently.

What activities should I avoid after total knee replacement?

Avoid high-impact activities like running, jumping, and contact sports, which can wear out your implant faster. Most surgeons say walking, swimming, cycling, golf, and hiking are fine. Heavy lifting and kneeling on your operated knee should be limited. Your surgeon will give you specific guidance based on your implant and your goals.

How much pain is normal after total knee replacement?

Pain and swelling peak around two to three weeks after surgery, then gradually improve. Some discomfort during physical therapy is expected and normal. If pain is severe, not improving after a few weeks, or getting worse instead of better, contact your surgeon. Persistent pain can signal infection, blood clots, or other complications that need attention.

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're healthy enough. Recovery is harder because you can't use crutches or a walker as easily with both legs healing. Many surgeons prefer to do one knee at a time, spacing them several months apart so you can use one good leg during recovery from the other.