Knee replacement surgery (arthroplasty) is a procedure in which an orthopedic surgeon removes an entire damaged or diseased knee joint and replaces it with an artificial one (prosthesis). Artificial knees need to be both flexible and strong and able to function in the body without causing an immune system reaction.
Artificial knee joints can be made from titanium, or chrome and cobalt alloys, while a durable plastic called polyethylene is used as a lining. While traditional artificial knees last about 15 years, those made of newer materials such as UHMWPE (ultra-high molecular weight polyethylene) and polyethylene have the potential to last up to 20 or 25 years.
Knee joint replacement surgery can involve two types of replacements: cemented or cementless, and the difference between the two is how they are held in place in the body. Cemented knee joint replacements use a special bone cement that helps secure the components of the artificial joint. This type may be better for older, less active adults. In a cementless knee joint replacement, the components that fit inside the bone are made of a porous material that allows natural bone to grow into it. These versions may last longer than the cement type because there is no cement that can become loose. A patient and his or her orthopedic surgeon can discuss the risks and benefits of each before a decision is made.