What is Knee Replacement? Purpose, Procedure & Results

Knee replacement is a surgical procedure where damaged parts of your knee joint are removed and replaced with artificial components made of metal, plastic, or ceramic. This surgery helps restore function to a severely damaged knee that causes ongoing pain and limits your daily activities.

Your knee joint works like a hinge, allowing your leg to bend and straighten smoothly. When arthritis, injury, or other conditions damage the cartilage and bone in your knee, this smooth movement becomes painful and difficult. Knee replacement surgery gives you back that smooth, pain-free movement by creating a new joint surface.

What is knee replacement?

Knee replacement surgery involves removing damaged cartilage and bone from your thighbone, shinbone, and kneecap, then replacing these surfaces with artificial parts. The artificial joint, called a prosthesis, is designed to mimic the movement of a healthy knee.

There are two main types of knee replacement. Total knee replacement replaces the entire knee joint, while partial knee replacement only replaces the damaged portion. Your orthopedic surgeon will recommend the best option based on how much of your knee is damaged and your overall health.

The artificial knee components are made from materials that have been tested for decades. The metal parts are usually made from titanium or cobalt-chromium alloys, while the plastic components are made from ultra-high molecular weight polyethylene.

Why is knee replacement done?

Knee replacement surgery is recommended when severe knee damage causes persistent pain that interferes with your daily life and doesn't respond to other treatments. The goal is to relieve pain, restore function, and improve your quality of life.

The most common reason for knee replacement is osteoarthritis, which occurs when the cartilage in your knee wears away over time. This leaves bone rubbing against bone, causing pain, stiffness, and swelling. Other conditions that may lead to knee replacement include rheumatoid arthritis, post-traumatic arthritis from injury, and certain bone diseases.

Your doctor might recommend knee replacement if you experience severe knee pain that limits everyday activities like walking, climbing stairs, or getting up from chairs. You might also be a candidate if your knee pain disturbs your sleep or if other treatments like medications, physical therapy, or injections haven't provided adequate relief.

What is the procedure for knee replacement?

Knee replacement surgery typically takes 1 to 2 hours and is performed under general anesthesia or spinal anesthesia. Your surgeon will make an incision over your knee to access the joint and carefully remove the damaged bone and cartilage.

During the surgery, your surgeon will make precise cuts to remove damaged portions of your thighbone, shinbone, and kneecap. The artificial components are then secured to the remaining healthy bone using special cement or by allowing the bone to grow into the implant surface.

After positioning the new joint components, your surgeon will test the knee's movement and stability. The incision is then closed with stitches or staples, and a sterile bandage is applied. Most patients can expect to stay in the hospital for 1 to 3 days after surgery.

How to prepare for your knee replacement?

Preparing for knee replacement surgery involves several steps to ensure the best possible outcome. Your surgeon will provide specific instructions tailored to your situation, but preparation typically begins several weeks before your surgery date.

You'll need to complete pre-surgical testing, which may include blood tests, an electrocardiogram, and chest X-rays. These tests help your medical team ensure you're healthy enough for surgery and anesthesia. Your surgeon may also ask you to stop taking certain medications, particularly blood thinners, before surgery.

Physical preparation is equally important. Your doctor might recommend exercises to strengthen the muscles around your knee and improve your overall fitness. You should also prepare your home for recovery by removing tripping hazards, installing grab bars in the bathroom, and arranging for help with daily activities during your initial recovery period.

How to read your knee replacement results?

The success of knee replacement surgery is measured by pain relief, improved function, and your ability to return to daily activities. Most people experience significant pain reduction and can walk without assistance within a few weeks to months after surgery.

Your surgeon will monitor your progress through follow-up appointments and may use X-rays to check the position and stability of your new knee joint. These images help ensure the artificial components are properly positioned and that the bone is healing well around the implant.

Functional improvements typically include better range of motion, increased walking distance, and the ability to climb stairs more easily. Many people can return to low-impact activities like swimming, cycling, and golfing, though high-impact sports are generally not recommended with an artificial knee.

How to optimize your knee replacement recovery?

Recovery from knee replacement surgery involves active participation in rehabilitation and following your surgeon's guidelines. The key to successful recovery is starting physical therapy early and staying committed to your exercise program.

Physical therapy typically begins within 24 hours of surgery, even while you're still in the hospital. Your therapist will teach you exercises to improve circulation, prevent blood clots, and begin restoring knee movement. These exercises might seem challenging at first, but they're essential for achieving the best possible outcome.

At home, you'll need to continue your exercises and gradually increase your activity level. Most people can return to normal daily activities within 3 to 6 weeks, though complete recovery can take several months. Following your surgeon's restrictions on weight-bearing and activity levels is crucial for proper healing.

What is the best knee replacement outcome?

The best knee replacement outcome is achieving significant pain relief while maintaining good knee function and mobility. Most people experience excellent results, with studies showing that over 90% of knee replacements are still functioning well after 10 to 15 years.

An ideal outcome includes being able to walk without pain, climb stairs comfortably, and participate in daily activities without significant limitations. Many people can return to recreational activities like hiking, dancing, and playing golf, though the specific activities you can enjoy depend on your individual recovery and surgeon's recommendations.

Long-term success depends on several factors, including following post-surgery care instructions, maintaining a healthy weight, staying active with appropriate exercises, and attending regular follow-up appointments. Protecting your new knee joint from excessive wear and tear helps ensure it lasts as long as possible.

What are the risk factors for knee replacement complications?

While knee replacement surgery is generally safe and successful, certain factors can increase your risk of complications. Understanding these risk factors helps you and your surgeon make informed decisions and take steps to minimize potential problems.

Medical conditions that may increase your risk include diabetes, heart disease, and obesity. These conditions can affect healing and increase the risk of infection or other complications. Your surgeon will work with you to optimize your health before surgery and may recommend losing weight or better controlling diabetes if applicable.

Age and activity level also play a role in outcomes. While there's no strict age limit for knee replacement, older patients may have longer recovery times and higher risks of certain complications. Very active individuals might wear out their artificial knee faster, though this varies greatly from person to person.

Is it better to have knee replacement sooner or later?

The timing of knee replacement surgery depends on your individual situation, including your pain level, functional limitations, and response to other treatments. There's no universal "right" time, but there are important considerations for both earlier and later intervention.

Having knee replacement surgery sooner might be beneficial if your knee pain significantly limits your daily activities and quality of life. Waiting too long can lead to muscle weakness, loss of bone density, and changes in how you walk that might affect your recovery. Early intervention can also help maintain your overall fitness and activity level.

However, since artificial knees don't last forever, having surgery too early might mean needing revision surgery later in life. Your surgeon will help you weigh the benefits and risks based on your age, activity level, and how well you might tolerate future surgery if needed.

What are the possible complications of knee replacement?

Knee replacement surgery is generally very safe, but like any major surgery, it carries some risks. Understanding these potential complications helps you make an informed decision and know what to watch for during recovery.

Common complications that can occur include infection, blood clots, and stiffness. Infection can develop around the artificial joint and may require additional surgery to treat. Blood clots can form in the legs after surgery, which is why you'll receive medications and exercises to prevent them.

Less common but more serious complications include implant loosening, wear of the artificial joint components, and nerve or blood vessel damage. Some people may experience persistent pain or limited range of motion despite surgery. Revision surgery may be needed if the artificial joint wears out over time or if complications develop.

Very rare complications include allergic reactions to the implant materials, fractures around the artificial joint, and problems with wound healing. Your surgical team will monitor you carefully for signs of complications and provide prompt treatment if any issues arise.

When should I see a doctor for knee replacement evaluation?

You should consider seeing an orthopedic surgeon for knee replacement evaluation when conservative treatments haven't provided adequate relief and your knee pain significantly impacts your daily life. Don't wait until you're in severe, constant pain to seek evaluation.

Schedule an appointment if you experience persistent knee pain that limits your ability to walk, climb stairs, or perform daily activities. You should also consider evaluation if your knee pain disrupts your sleep or if you're avoiding activities you used to enjoy because of knee discomfort.

Other signs that warrant evaluation include knee deformity, instability, or if your knee pain doesn't respond to medications, physical therapy, or other treatments your primary care doctor has recommended. Early evaluation doesn't mean you need surgery immediately, but it helps you understand your options and plan for the future.