Partial vs Total Knee Replacement: Key Differences, Benefits, and Outcomes

Knee replacement surgery can make a big difference for people with serious knee pain, but choosing between partial and total knee replacement is not always simple. The main difference is that partial knee replacement only treats the damaged area, while total knee replacement replaces the whole joint. This decision affects recovery, possible risks, and how the knee will work in the future.

Partial knee replacement is usually an option when damage is limited, while total knee replacement is better for those with widespread arthritis or injury across the knee. Each method has its own benefits and possible downsides, so understanding both options is important. To help patients make an informed choice, it’s helpful to know what each surgery involves, the expected outcomes, and who might be a good candidate for each type of procedure.

Key Takeaways

• Partial treats one part of the knee, total replaces the whole joint.
• Recovery time and risks differ between the two options.
• The best choice depends on the person’s knee damage and health.

Comparing Partial and Total Knee Replacement

Partial and total knee replacements are both common options for people with knee joint damage or osteoarthritis. Each method offers different benefits, recovery times, and uses depending on the parts of the knee affected by disease or injury.

Definition of Partial Knee Replacement

Partial knee replacement is also called unicompartmental knee replacement or unicondylar knee replacement. It means only the damaged part of the knee joint is replaced with a prosthetic implant. The most common area treated in this surgery is the medial compartment, but sometimes the lateral compartment or patellofemoral compartment may be involved.

Unlike total knee arthroplasty, this procedure preserves healthy cartilage, ligaments, and bone in the untouched compartments of the knee. Because of this, partial knee replacement is less invasive and generally requires a smaller incision.

Partial knee replacement is usually best for people whose knee arthritis or damage is limited to one compartment of the knee joint. It is often recommended for younger or more active patients who still have good joint stability and healthy surrounding tissue.

Definition of Total Knee Replacement

Total knee replacement, also known as total knee arthroplasty (TKR or TKA), involves removing damaged cartilage and bone from all three compartments of the knee: medial, lateral, and patellofemoral. Surgeons then replace these areas with artificial components to restore normal motion and reduce pain.

This procedure is more extensive than partial knee replacement, as it affects the whole knee joint rather than just one section. TKR is most suitable for patients with severe arthritis or joint degeneration that affects more than one compartment. Many older adults or those with severe deformities are likely candidates.

Recovery after total knee replacement may take longer compared to partial procedures. Doctors often recommend this surgery when nonsurgical treatments, such as medication or therapy, no longer provide enough relief.

Key Differences in Surgical Approach

Partial knee replacement is considered less invasive. The surgeon makes a smaller incision and focuses only on the damaged area, leaving most of the natural knee structure intact. This helps with faster recovery and allows the knee to feel more natural after healing.

In total knee replacement, the surgeon makes a larger incision and completely replaces the cartilage and bone in all compartments of the knee. This approach addresses widespread knee damage but also removes more natural tissue. Patients who get a total knee replacement typically experience longer recovery periods and a higher risk for complications, but greater overall relief for advanced arthritis.

Both procedures use prosthetic parts, but their placement and the amount of tissue removed can affect things like pain, flexibility, and knee function after surgery.

Knee Joint Compartments Involved

The knee joint contains three main compartments:

• Medial compartment: inside portion of the knee
• Lateral compartment: outside portion of the knee
• Patellofemoral compartment: area behind the kneecap

Partial knee replacement targets only one of these compartments, most often the medial compartment. Surgeons select this method if the damage is not widespread, and the rest of the knee remains healthy.

Total knee replacement, by definition, involves all three compartments. This is necessary when arthritis or injury is found throughout the joint, not limited to one spot. Patients needing full relief from pain in multiple compartments usually require total knee arthroplasty. 

Ideal Candidates and Indications for Surgery

Choosing the right knee replacement surgery depends on where the knee is damaged, what type of arthritis is present, and how severe the pain is. Orthopedic surgeons like Dr. Mangino also looks at ligament strength and other health factors before recommending a procedure.

Who Is Eligible for Partial Knee Replacement

Partial knee replacement is best for patients with osteoarthritis or knee arthritis limited to one part of the knee, often the medial, lateral, or patellofemoral compartment. If the rest of the knee, including crucial ligaments like the posterior cruciate ligament and healthy meniscus tissue, is in good condition, partial replacement can be a good option.

Candidates are usually not bow-legged or knock-kneed, as these conditions often mean damage is seen in more than just one compartment. Partial replacement is also preferred for people who still have a decent range of motion and whose ligaments are strong. Patients with inflammatory arthritis, such as rheumatoid arthritis, are typically not good candidates because their arthritis often affects the entire knee.

Most individuals trying partial replacement have not improved with medications, injections, or physical therapy. They should be in otherwise good health before surgery.

When Total Knee Replacement Is Recommended

Total knee replacement is used when arthritis or joint degeneration affects two or more areas of the knee. This procedure is common for people who have pain at rest, pain at night, or serious trouble with activities like walking, climbing stairs, or even sleeping.

It helps people with advanced osteoarthritis, long-term rheumatoid arthritis, or other types of inflammatory arthritis, especially when other treatments have failed. Severe deformities, such as being very bow-legged or knock-kneed, may also mean that a total replacement is needed. In these situations, the meniscus and large ligaments are often too damaged for partial replacement to be successful.

Orthopedic surgeons like Dr. Mangino will consider this option if the joint is unstable, the posterior cruciate ligament is weak, or non-surgical treatments no longer provide relief.

Factors Affecting Candidacy

Many factors play a role in deciding between partial and total knee replacement. The patient's age and activity level are important. Partial replacement is often recommended for individuals over 60 with stable ligaments and no major knee alignment problems. Meanwhile, total replacement can suit a wider age group if arthritis is severe.

Other medical conditions are also important. People with severe osteoporosis, poor skin health, or major infections may need to delay or avoid surgery. The health of the surrounding ligaments, especially the posterior cruciate ligament, is carefully checked. Joint damage from conditions like rheumatoid arthritis, or poor meniscus health, may mean a full replacement is needed.

Before surgery, orthopedic surgeons use imaging tests, physical exams, and a review of other treatments tried, such as medication and therapy, to choose the most effective option.

Dr. Mangino will guide you through this evaluation process by asking the right questions and performing the necessary tests to determine the most appropriate surgical option for your case, ensuring you receive a clear and personalized recommendation. 

Frequently Asked Questions

Partial and total knee replacements have different recovery times, risks, and long-term outcomes. The procedures are also different in how much of the knee is replaced and how the results can be seen on x-rays.

What is the difference in recovery time between partial and full knee replacements?

Most people who have a partial knee replacement recover faster. Walking without assistance is often possible in three to four weeks. For total knee replacement, walking with assistance takes longer, and it may take several weeks before walking unaided is possible. Maximum strength and mobility after either surgery can take six months to one year.

What are the disadvantages of opting for a partial knee replacement?

Partial knee replacement can have a higher chance of needing another surgery in the future. If the other parts of the knee wear out later, a new surgery may be necessary to convert to a total knee replacement. There is also a chance for more complicated revision surgery if a partial knee replacement fails. Not everyone is a good candidate for partial knee replacement, especially younger or very active people, or those with damage in more than one part of the knee.

How does recovery from partial knee replacement compare after 3 months?

After three months, most people with a partial knee replacement have returned to many normal activities. They may still need to avoid high-impact sports, but low-impact activities like walking or biking are often possible. Recovery from total knee replacement is usually slower. Many people are still regaining full strength and flexibility at the three-month mark, but pain relief and mobility continue to improve.

What is the success rate of partial knee replacements compared to total knee replacements?

Studies show that about 90% of partial knee replacements are still working well after ten years, and about 70% last for 25 years. For total knee replacements, about 90% are still functional after 20 years. Total knee replacements may have slightly lower risks of requiring a second surgery later on. 

How do partial and total knee replacements differ on x-rays?

On an x-ray, a partial knee replacement will show a prosthesis on only one part of the knee joint, usually the inside (medial) side. A total knee replacement will show artificial components on all three compartments of the knee. The structures of the knee look more extensively replaced on x-rays after a total knee replacement.