What Is Knee Replacement Surgery?

Knee replacement, also known as knee arthroplasty, is a surgical procedure in which the damaged parts of the knee joint are removed and replaced with artificial parts or prostheses. The prostheses are typically made of metal and plastic and are designed to mimic the function of a healthy knee joint.

It’s typically only considered after all, or most nonsurgical options have been exhausted, and if your quality of life is significantly impacted by the pain.

Types of Knee Replacements

There are several types of knee replacement surgery available, including:

• Total knee replacement (TKR): The most common type, which involves removing the damaged parts of the knee joint and replacing them with artificial parts, or prostheses, typically consists of a metal component that replaces the thigh bone (femur) and a plastic component that replaces the shin bone (tibia).
• Partial knee replacement (PKR): Also known as unicompartmental knee replacement, involves replacing only the damaged part of the knee joint rather than the entire joint and is typically recommended for individuals with arthritis that is confined to one compartment of the knee.
• Revision knee replacement: A type of knee replacement surgery performed when a previous knee replacement surgery has failed or has become loose. It involves removing the previous prosthesis and replacing it with a new one.
• Customized knee replacement: This type of knee replacement surgery is done by using a CT scan of the patient’s knee and using the data to create a prosthesis that is customized to the patient’s individual knee anatomy.
• Minimally invasive knee replacement: This type of knee replacement surgery is done through a smaller incision, which can reduce recovery time and minimize tissue trauma.

Underlying Causes

Knee replacement surgery is typically recommended for individuals with severe knee pain or disability caused by osteoarthritis, rheumatoid arthritis, or other similar conditions. Not everyone with knee arthritis will need a knee replacement, and the decision is typically based on the balance between the pain and disability caused by the knee problem and the risks and benefits of the surgery. Your doctor will consider your overall health and your goals for treatment.

Osteoarthritis is the most common reason for knee replacements, which is a degenerative condition that causes the cartilage in the knee joint to wear away. Rheumatoid arthritis, another main reason for replacement, is an autoimmune disorder that causes inflammation in the joints.

Other conditions that can lead to knee replacement surgery include trauma or injury to the knee joint that has caused damage to the cartilage or bones, gout, a type of arthritis caused by the buildup of uric acid crystals in the joint, osteonecrosis, where the bone tissue dies due to a lack of blood supply; and pseudogout, a type of arthritis that causes a buildup of calcium pyrophosphate crystals in the joint.

What Are the Signs You Might Need a Knee Replacement?

Signs that may indicate a need for a knee replacement are:

• Severe pain: Pain in the knee joint that interferes with daily activities and is not relieved by over-the-counter pain medication.
• Stiffness: Difficulty in moving the knee joint or feeling stiffness in the joint, especially in the morning or after sitting for long periods.
• Swelling: Inflammation and swelling in the knee joint which can make the knee appear red and warm to the touch.
• Bone-on-bone: A feeling of bone grinding on bone in the knee joint, which can be accompanied by a clicking or popping sound.
• Loss of function: Difficulty in standing up, climbing stairs, or walking, which can make it hard to perform daily activities.
• Deformity: A visible deformity in the knee joint, such as a bowlegged or knock-kneed appearance.

Who is a Good Candidate for Knee Replacement Surgery?

Even if your knee shows symptoms of needing a replacement, not everyone is a good candidate for replacement surgery, perhaps due to certain medical conditions or other factors, including:

• Advanced age may cause some to not be able to tolerate surgery or may not be able to recover as well. Knee replacements are becoming more common in younger patients, as well as those who are more active.
• Obesity and severely overweight people may not be good candidates for knee replacement surgery because of a higher risk of complications during and after the surgery.
• Active infections anywhere in their body may need to wait for surgery until treated and cleared.
• Severe osteoporosis may cause a higher risk of complications during and after the surgery.
• Certain psychological conditions affect the ability for some to make decisions or follow through with postoperative rehabilitation.
• Other diseases: Individuals with rheumatoid arthritis, lupus, or other connective tissue disorders may not be good candidates.

While these factors are not absolute contraindications for knee replacement surgery, each case is evaluated individually. Your doctor will consider the condition of your knee and your overall health and lifestyle.