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How Do You Know If You Need a Knee Replacement?

Osteoarthritis of the knees becomes increasingly common as people get older. When the cartilage that’s supposed to provide cushioning between the bones that meet at the knee joint begins to degenerate and wear away, the bones rub together. This can cause significant pain. It also can lead to inflammation and swelling, which may affect your ability to bend and straighten your leg.

Degeneration of the cartilage in the knee may be worse or may happen earlier in life if you have had a knee injury. Obesity may also make it more severe, because there is more weight being placed on the joints.

If you’re having problems with knee pain and swelling due to osteoarthritis, there are a number of nonsurgical treatments you can try. Anti-inflammatory drugs such as ibuprofen, certain exercises and injections offer relief for many people. If your problems can be controlled with these other measures, you don’t need to have surgery. But if it gets to the point where you’re staying home because it hurts too much to walk, or you’re unable to do simple activities like climbing stairs, it may be time to seriously consider having knee replacement surgery.

To qualify for a knee replacement, you need to meet two major requirements. One is that you have a sufficient amount of loss of cartilage. The other is that the loss is bad enough that it’s having a negative impact on your quality of life—due to either pain, limited function or a combination of the two. Usually by the time people come to me, they have tried everything else and are ready to have surgery.

The term “knee replacement” may be scary. It makes the surgery sound very different from what it actually is. What we do in a modern knee replacement is replace the surfaces of the knee joint, not the joint itself. The tendons, ligaments and all the other structures around the knee are left in place. I sometimes compare it to a dentist capping a tooth: We are adding new caps to the bones.

The knee is divided into three compartments:

  • inner side (called the medial compartment)
  • outside (the lateral compartment)
  • front (the kneecap or patellofemoral compartment)

If you have a problem in only one of the three compartments, you may have what is called a partial knee replacement. But the majority of people who undergo knee replacement surgery—about 90%—need to have all three compartments repaired. This is called a total knee replacement, or total knee arthroplasty.

Many people with osteoarthritis have problems with both knees, but usually one knee is worse than the other. Most people have surgery on one knee at a time, though some patients want to have surgery on both knees at the same time. The plus side of this is that you only need one operation, but the downside is that it’s a harder, slower recovery. There are strict criteria for having both knees operated on at the same time, including being in overall good health and being motivated to undergo a more difficult recovery.

I call knee replacement surgery a team sport. The two most central players are the surgeon and the patient, but there are many other people on the team who help make it successful.

Dr. Steven Haas, hip and knee surgeon

Dr. Steven B. Haas is Chief of the Knee Service at HSS and holds the John N. Insall Chair in Knee Surgery. He is a leader in advancing surgical techniques and pain control, which allows for more rapid recovery from knee replacement.



The information provided in this blog by HSS and our affiliated physicians is for general informational and educational purposes, and should not be considered medical advice for any individual problem you may have. This information is not a substitute for the professional judgment of a qualified health care provider who is familiar with the unique facts about your condition and medical history. You should always consult your health care provider prior to starting any new treatment, or terminating or changing any ongoing treatment. Every post on this blog is the opinion of the author and may not reflect the official position of HSS. Please contact us if we can be helpful in answering any questions or to arrange for a visit or consult.