Is it the right time for a knee replacement? Age alone is no bar to surgery. Older and younger people benefit equally, as long as they are generally healthy to start. However, people under 60 are encouraged to delay total knee replacement if they can. The reason? Artificial joints have a limited life span. Assuming an average level of physical activity, you can expect today's joint implants to last 15 to 20 years—sometimes longer. However, if you are overweight or more physically active than average, your new joint will face additional stress and may wear out faster. Get your copy of Total Knee Replacement   If you need a replacement, or think it’s time to seriously consider it, Harvard’s Total Knee Replacement guide is invaluable. This guide can help you make that important decision, in consultation with your primary care doctor and orthopedic specialist. You’ll find a list of critical questions to ask your doctor to help ensure you have the best possible surgeon. The guide explains why people end up needing knee replacement, the alternatives to surgery, the different types of knee implants, the risks and complications of surgery, and how to make a safe and full recovery. Ideally, you want your first knee replacement to be your last. Given the average life span for Americans, most older adults who get a new knee will not need to have it replaced. The situation is more complicated if you are in your 40s or 50s. In this case, the new knee is more likely to wear out during your lifetime. Then you'll need to have a revision surgery to take out the old one and replace it. The number of people under age 55 having knee replacements is growing rapidly. But it's also possible to wait a bit too long. If the joint becomes crooked because of breakdown of cartilage and bone, it can make the surgery more complicated. (Such deformities can make you bow-legged or knockkneed.) Some research also suggests that it may provide less benefit in the long term for people who wait until they have significant disability to get surgery. But other research finds no difference in results for people who wait longer. The decision about when to have knee replacement is a highly individual one, further highlighting the need for shared decision-making between you and your doctor. To learn more about your options for knee replacement surgery, read the Harvard Medical School guide Total Knee Replacement. Image: © Wavebreakmedia/Getty Images Share this story:

4 types of knee implants Thinking about a total knee replacement? There are a few different kinds of knee implants that are used in this procedure. The different types are categorized by the materials that rub against each other when you flex your knee: Metal on plastic. This is the most common type of implant. It features a metal femoral component that rides on a polyethylene plastic spacer attached to the tibial component. The metals commonly used include cobalt-chromium, titanium, zirconium, and nickel. Metal-on-plastic is the least expensive type of implant and has the longest track record for safety and implant life span. However, one problem that can happen with plastic implants is an immune reaction triggered by tiny particles that wear away from the spacer. This can cause bone to break down, leading to loosening and failure of the implant. Advances in manufacturing have greatly reduced the rate of wear in the plastic. Ceramic on plastic. This type uses a ceramic femoral component instead of metal (or a metal component with a ceramic coating). It also rides on a plastic spacer. People who are sensitive to the nickel used in metal implants might get the ceramic type. Plastic particles from this type of implant also can lead to an immune reaction. Ceramic on ceramic. The femoral and tibial components are both made of ceramic. Ceramic parts are the least likely to react with the body. However, ceramic joint prostheses can make a squeaking noise when you walk. In rare cases, they can shatter under heavy pressure into pieces that must be removed by surgery. Metal on metal. The femoral and tibial components are both made of metal. Metal-on-metal implants have been used much less often in recent years because of concerns over traces of metal leaking into the bloodstream. The metal comes from the chemical breakdown of the implant hardware. All metal implants originally were developed to provide longer-lasting joint replacements for younger people.But the traces of metal can cause inflammation, pain, and possibly organ damage. Metal-on-metal implants may be considered only for young, active men, because they may last longer than other materials. Women of childbearing age can't receive these implants because the effects on a fetus are not known. To learn more about your options for knee replacement surgery, read the Harvard Medical School guide Total Knee Replacement. Image: m-gucci/Getty Images Share this story:

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Total Knee Replacement Featured content: • Are your knees worn out? • Arthritis: Why knees wear out • Knee anatomy • Deciding about knee replacement • Next steps before surgery • Types of implants • Surgical decisions Click here to read more »