Total knee replacement is usually effective at easing symptoms of severe knee arthritis. However, in rare cases, you may experience complications, such as infection or the need for revision surgery.

Total knee replacement surgery, also known as total knee arthroplasty, involves resurfacing the worn-out surfaces of the knee joint with a prosthetic device that carries out the same functions as your knee.

Every year in the United States, surgeons carry out approximately 700,000 total knee replacements, according to the American Academy of Orthopaedic Surgeons (AAOS).

Keep reading to learn more about the statistics and clinical outcomes of total knee replacement surgery.

A successful total knee replacement typically leads to a higher quality of life, less pain, and better mobility.

For example, it could help you stay active and return to a wide range of low impact activities you previously enjoyed, such as:

More than 90% of replacement knees are still functioning well after 15 years, according to the AAOS. After 25 years, nearly 82% of total knee replacements are still functioning.

Knee replacement surgery is relatively safe and effective for most people.

That said, 2 in 100 people may experience a severe complication, such as infection or blood clot.

In rare cases, it’s possible to experience infection after knee replacement surgery. This is known as periprosthetic joint infection.

In 1981, one expert estimated that the infection rate for knee surgery was 9.1%.

However, newer practices of giving antibiotics during and after the operation have reduced the risk to less than 1%, according to the American Association of Hip and Knee Surgeons.

Knee replacement infection may happen during the replacement surgery, a few days later, or even years later.

Some risk factors may increase your risk of knee replacement infection, including:

Blood clots may develop after surgery. These are called deep vein thromboses (DVTs). If a DVT breaks off and travels to the lungs, it results in a pulmonary embolism (PE), which can be life threatening.

A 2023 study found that 1.19% of people who received a total knee or hip replacement experienced DVT. In the study’s introduction, however, the authors note that DVT has been shown to occur in up to 3% of knee and hip replacements.

Risk factors associated with DVT after knee replacement surgery include having a history of DVT and hypercoagulability (thick blood).

To reduce the risk of a blood clot, you’ll typically be prescribed a blood thinner after surgery.

Osteolysis (destruction of bone) is a common complication of knee replacement surgery.

It may happen when microscopic debris from the prosthetic knee, such as plastic or metal, causes inflammation. It could also happen due to the loosening of the knee joint over time.

Stiffness, or arthrofibrosis, is one of the more common complications after knee replacement surgery. It occurs when excessive scar tissue forms in the knee and limits the movement of the new joint.

The best way to avoid stiffness is to follow the exercise regimen your healthcare team recommended after surgery.

Most people experience a significant improvement in knee pain after total knee replacement surgery. However, up to 20% of people may continue to experience low levels of knee pain despite a well-performed operation.

Knee replacement revision surgery is when you need a second knee replacement at some point after your initial operation.

From 2012–2019, revision surgeries significantly increased by 29.6%.

The three most common risk factors associated with knee replacement revision surgery include:

  • prosthetic knee loosening and wear
  • prosthetic knee instability
  • periprosthetic joint infection

A 2017 study found that people who receive their initial knee surgery at a younger age are more likely to require revision surgery. For example:

  • 4.4–7.1% of people over 70 years old may require revision surgery
  • up to 15% of people ages 60–69 years may require revision surgery
  • up to 35% of males and 20% of females ages 50–59 years may require revision surgery

What percent of knee replacements are successful?

Research suggests that over 90% of replacement knees still function well after 15 years and 82% after 25 years.

What is the regret rate for knee replacement?

Research suggests that just over 6% of people report not being satisfied with their total knee replacement surgery. People who undergo robotic knee replacement also have the highest satisfaction rates.

What is the failure rate of knee replacements?

According to the American Association of Hip and Knee Surgeons, 0.5–1% of total knee replacements fail yearly.

What is the best age to have a knee replacement?

Research suggests that the best age to have a knee replacement is between ages 70–80 years because you’re less likely to require revision surgery. That said, the authors report no significant difference in people younger than age 70 years.

Total knee replacement surgery may help increase your mobility, knee function, and quality of life.

However, it’s important to discuss the potential side effects and complications of getting a total knee replacement with a healthcare professional during the evaluation process.

Sometimes, they may not recommend surgery because the potential risks outweigh the benefits.