Total joint replacement improves the quality of life for more than a million Americans each year suffering from hip or knee pain. According to the Center for Disease Control (CDC), in 2015 alone, there were 719,000 total knee replacements and 332,000 total hip replacements performed. There are more than seven million Americans living with knee or hip implants today.
Traditionally there has been concern about the longevity of joint replacement implants. Until a decade ago, joint replacement procedures were performed mainly on patients in their 60s and 70s because it was believed the implants wouldn't last more than 15 to 20 years. However, recent studies have found that around 90 percent of hip and knee replacements are still functioning after 20 years.
Even so, there has been a need for longer-lasting joint replacements driven by an increased demand for implants by younger, more active patients. An increasing number of patients in their 40s and 50s are getting joint replacements and their expectations aren't just to get knee or hip replacements that last longer, but that also allow them to maintain their active lifestyles.
Getting a joint replacement used to be about being able to perform essential tasks, like walking. Nowadays patients are younger and want to continue engaging in activities they love, like skiing, golfing, and playing tennis. Thanks to modern joint replacements, they can.
What Affects the Longevity of a Joint Replacement?
The longevity of a joint replacement is determined somewhat by its materials. A natural human joint uses cartilage, which provides a frictionless buffer between bones to prevent them from wearing down over time. Artificial joint replacements have a small amount of friction which causes components to wear down over time.
The wear not only leads to the joint replacement becoming unusable but the friction of the materials causes particles 200 times smaller than a grain of sand to be released into the joint cavity. These particles can cause discomfort and even significant inflammation and pain. It can also cause osteolysis around the replacement, which is destruction of the bone.
A lower level of friction between a knee or hip replacement materials results in less wear and a lower risk of osteolysis. The longer a joint replacement lasts the more viable it is as a knee or hip treatment for younger patients, which minimizes the need for revision surgery.
Types of Materials Used in Knee and Hip Replacements
In the 1960s and 1970s, various materials were used as bearing surfaces in hip and knee replacements, including stainless steel, cobalt-chromium and Teflon®. In the 1980s and 1990s, the preferred combination was cobalt-chromium and ultra-high molecular weight polyethylene (a medical grade plastic). Polyethylene creates very little friction when used in conjunction with a highly polished metallic surface.
There are various materials in use today. While metal-on-metal has been used in the past for hip replacements, it has fallen out of favor due to the better overall performance of metal-on-polyethylene and ceramic-on-polyethylene.
Manufacturing and metallurgy have come a long way in the past twenty years. Cobalt-chromium alloys are now much stronger and have a higher level of wear-resistance compared to their predecessors. Ceramic-on-polyethylene combinations have also gained popularity due to the hardness and smoothness of ceramic and the much lower wear rates they offer. After a decade of use there have been lower wear rates observed, making these joint replacements a good knee or hip treatment option for younger, more active patients.
As medical technology continues to advance we will continue to see joint replacement materials last longer and cause less friction. Joint replacements will become stronger and their lifespans will increase significantly, which means younger patients will be able to benefit without the need for revision surgery later in life.
When it comes to choosing a hip or knee replacement, your age, activity level, weight, and the joint problems you exhibit will all factor into identifying and ultimately selecting the right joint replacement. At Augusta Health's Joint Center, our highly experienced surgeons take a personalized approach to each and every patient to ensure your exact needs are met.
If knee or hip pain is preventing you from getting the most out of life, give us a call at (540) 332-5047 to talk with our Joint Center about your options.