Since its introduction in the United States in the1960s, hip replacement surgery has changed the lives of millions of Americans, giving folks a chance to get back to doing the activities they once enjoyed before their hip became injured or damaged. For many, a new hip is a return to living life to its fullest, whether it’s resuming favorite pastimes or simply being able to walk again without pain.
Today hip replacement surgeries are performed routinely in the United States. It’s the second most common joint replacement procedure, after knee replacements. The American Academy of Orthopaedic Surgeons reports that more than 250,000 hip replacements are performed in the United States each year.
And it’s a procedure with outstanding results. According to the Mayo Clinic, hip replacement surgery is successful more than 90 percent of the time.
Many factors influence the success of hip surgery. One aspect to consider is the choice of implant. Here at El Camino Hospital, our surgeons have extensive experience with various types of implants and are happy to discuss the many options with you.
What exactly is “replaced” in a hip replacement?
A typical hip replacement (or hip arthroplasty) involves removing a diseased hip joint and replacing it with an artificial joint, known as a “prosthesis.” A prosthesis consists of a “ball” (made of metal or ceramic) and a “socket” (which has an insert made of plastic, metal or ceramic).
Is the choice of implant materials important?
The two basic rules of materials used in hip implants are that they must be:
- Biocompatible -- so that your body will accept the new materials
- Resistant to corrosion, degradation and wear – so that they will last a long time
As researchers look at developing new types of implants, both of these factors are taken into consideration. Some materials are stronger in one area than in the other. All have their advantages and disadvantages, which your surgeon will discuss with you in detail.
For a look at what materials are used in the implants that are available today, see the implant descriptions below.
What influences what type of implant is used?
Here at El Camino Hospital, our orthopedic surgeons look at several factors when determining which type of implant to choose for a patient. These include:
- your age, as hip replacements are now done in the old and the young
- your activity level, including whether you’re involved in sports or other active pursuits
- your weight, because excess weight puts more stress on an implant
- any other conditions you may have
- their personal experience using different implants
What types of implants are available? How long do they last?
Over the years, researchers have performed hundreds of studies on hip implants, and, overall, the data shows that most common types of hip replacements can last 20 years or more. Some last even longer, but in general there tends to be a drop-off in success rates around the 20-year mark.
So, much research has gone into whether or not hip replacements can be designed to last even longer than 20 years. So far, data on some of the newer implants has been very promising, and over the next decade more information will become available concerning their long-term success in patients.
Listed below are some of the most commonly used hip implants, along with some points to consider for each implant type.
- Metal and Plastic – Most hip replacements are currently a combination of metal and plastic. The ball and socket portions of the new joint are metal (either titanium, stainless steel or cobalt-chrome) and the spacer between them is plastic (polyethylene). Research has shown that the plastic portion tends to wear out more quickly than the metal, so new implants have been created in the past decade that use a different combination of materials.
- Metal-on-Metal – In the newer, metal-on-metal implants, introduced in the United States in 2002, the plastic piece between the metal ball and the metal socket has been removed. Studies have shown that these all-metal implants do not wear out as quickly as the conventional metal-and-plastic implants mentioned above. Less wear and tear means that patients can have more freedom of activity than with implants that have the less durable plastic material in them.
- Ceramic-on-Ceramic – Ceramic-on-ceramic implants, where both the ball and socket are ceramic, were created to be the most wear-resistant hip replacement implants. Studies have shown that they perform better than even the metal-on-metal implants when it comes to measuring wear over time. Scientists are still studying their long-term effectiveness in patients, however, and that data should become available in the coming years.
- Metal and Highly Cross-Linked Polyethylene – Recently, special plastics designed to be more resistant to wear have been introduced for use in hip implants. They are known as “cross-linked plastics” and are manufactured in a way that they wear out less quickly than other plastics. Cross-linked plastics have only been in use for a few years, so we don’t know how they compare to other implants after decades of use. Based on studies, researchers predict that they would likely last quite a long time, which is certainly exciting news for younger hip patients.
How will my surgeon decide what implant is right for me?
At El Camino Hospital, our surgeons will spend considerable time discussing with you whether or not hip surgery is the best option for you, and if so, what type of implant would be most appropriate based on your medical history. Unlike other hospitals, El Camino Hospital does not restrict a surgeon’s choice of hip implant to just one brand or model. Our orthopedic surgeons have full access to all available implant options, which means you will get the best available implant for you based on your particular needs.