When it comes to joint replacement—including the hip—patients often wonder how long it will last. The definitive answer to that is, “It depends.” One of the most difficult things to quantify and anticipate is the amount and intensity of a new joint’s use.
Although it’s impossible to predict how much use the new joint must endure, some studies show that males have greater wear. Studies also show that younger, more active patients have more wear.
Where’s the Wear?
Before explaining the location of wear, let me define the hip joint, which is made up of two main parts. These include the ball (femoral head) of the thigh bone, which fits into the socket (acetabulum) of the pelvis. Capsular tissue connects the ball to the socket and helps provide stability to these parts.
The place where the two parts of the hip glide together during motion is known as the bearing surface. This is where the wear occurs. There are three types of bearing surfaces used in joint replacement today.
Metal-on-Plastic
When this option was used in the 1960s, it was a hard ball rubbing against soft plastic. Prior to placement, this plastic was irradiated (using ionizing radiation to kill bacteria)—which later was found to weaken it. Today’s metal-on-plastic bearing surfaces perform better due to a stronger plastic and the fact that radiation no longer is used.
Studies show this option wears more than the other two. It also creates more debris. Typically, most of this wear is seen during the first 12 months, then seems to stabilize.
One significant benefit to a metal-on-plastic bearing surface is it can be made using a larger ball (femoral head), providing more stability. Another benefit of this component is that it’s time-tested with more than 40 years of use in millions of patients. Although the earlier versions were made of weaker plastic, today’s implants are manufactured with stronger, more durable plastic.
Metal-on-Metal
The metal-on-metal bearing surface has less volume of wear. Typically, patients who receive this joint experience less tissue inflammation near the replacement site, making it more likely for the component to remain firmly in place. This option produces smaller debris particles, but a greater number of them. Yet because they’re smaller particles, the overall volume is lower than is produced with other bearing surfaces.
The volume of particles is lower; however, there is an increase in metal ion levels in the bloodstream. Pregnant women, those who may become pregnant, individuals with compromised renal function, or people with metal sensitivity aren’t good candidates for metal-on-metal bearing surfaces.
As with the metal-on-plastic implant, the metal-on-metal option can use a larger head, providing increased stability. Although there’s less debris with this implant, mid-term results showed some failures without a clear reason as to why they occurred.
Ceramic-on-Ceramic
This option has the reputation of extreme resistance to wear with minimal particle debris. But because they’re brittle, there’s a risk of fractures and squeaks. However, the manufacturer of this bearing surface claims these negative factors have been resolved. The belief is that today’s ceramic-on-ceramic bearing surfaces are made from small grains, which ensure cohesiveness and a reduction in fractures. In the 1990s, this type of bearing device was sometimes prone to fractures because of its construction from large grains.
One of the disadvantages to the ceramic option is the limit in size—both in the size of the head and in the length.
What’s right for me?
The three types of implant options don’t seem to present a clear-cut leader. However, each manufacturer claims its type of replacement joint is the best and has fewer problems than its competitors.
In most cases, the first generation of testing surgeons are those who have a financial interest in the success of new components. Therefore, it’s no surprise that the initial studies show “great” results and the new implants are promoted as “forever hips.” The truth is the current studies are based on short-term and mid-term use (up to about five to seven years).
The second generation of testing physicians are orthopedic surgeons who don’t have a vested interest in the implants’ success and are using them in their day-to-day patient care. The most recent studies (from professional journals) are showing excellent results at mid-term follow-up.
Because it’s impossible to predict long-term success, it takes years of observation and studies to determine the actual lifespan of a new component. There aren’t yet studies that demonstrate long-term use (10 to 15 years) of these newer components, so the jury is still out on which implant offers the best results. The bottom line is patients need to evaluate the studies and choose an orthopedic surgeon they trust to recommend the most appropriate option.
Choosing an Orthopedist
Oddly enough, some people spend more time researching a new hair stylist than a surgical specialist. In addition to asking your primary care physician for a referral to an orthopedic surgeon, there are a few other things you can do to ensure a good “fit” for you or a family member.
Ask friends and family members about their experiences with any local orthopedic surgeons. During your initial appointment with a new surgeon (or physician of any type), be sure you feel comfortable with the interaction you have. Does she listen to you? Does she clearly explain your options? Because there are several different types of implants and techniques used for joint replacement, be sure your physician is knowledgeable about all of the options available so she can recommend what is appropriate for your condition, lifestyle, and needs.
Fortunately, today’s technology gives us more options to provide patients with the best care possible so they can get back to the activities they enjoy. TPW
Although it’s impossible to predict how much use the new joint must endure, some studies show that males have greater wear. Studies also show that younger, more active patients have more wear.
Where’s the Wear?
Before explaining the location of wear, let me define the hip joint, which is made up of two main parts. These include the ball (femoral head) of the thigh bone, which fits into the socket (acetabulum) of the pelvis. Capsular tissue connects the ball to the socket and helps provide stability to these parts.
The place where the two parts of the hip glide together during motion is known as the bearing surface. This is where the wear occurs. There are three types of bearing surfaces used in joint replacement today.
Metal-on-Plastic
When this option was used in the 1960s, it was a hard ball rubbing against soft plastic. Prior to placement, this plastic was irradiated (using ionizing radiation to kill bacteria)—which later was found to weaken it. Today’s metal-on-plastic bearing surfaces perform better due to a stronger plastic and the fact that radiation no longer is used.
Studies show this option wears more than the other two. It also creates more debris. Typically, most of this wear is seen during the first 12 months, then seems to stabilize.
One significant benefit to a metal-on-plastic bearing surface is it can be made using a larger ball (femoral head), providing more stability. Another benefit of this component is that it’s time-tested with more than 40 years of use in millions of patients. Although the earlier versions were made of weaker plastic, today’s implants are manufactured with stronger, more durable plastic.
Metal-on-Metal
The metal-on-metal bearing surface has less volume of wear. Typically, patients who receive this joint experience less tissue inflammation near the replacement site, making it more likely for the component to remain firmly in place. This option produces smaller debris particles, but a greater number of them. Yet because they’re smaller particles, the overall volume is lower than is produced with other bearing surfaces.
The volume of particles is lower; however, there is an increase in metal ion levels in the bloodstream. Pregnant women, those who may become pregnant, individuals with compromised renal function, or people with metal sensitivity aren’t good candidates for metal-on-metal bearing surfaces.
As with the metal-on-plastic implant, the metal-on-metal option can use a larger head, providing increased stability. Although there’s less debris with this implant, mid-term results showed some failures without a clear reason as to why they occurred.
Ceramic-on-Ceramic
This option has the reputation of extreme resistance to wear with minimal particle debris. But because they’re brittle, there’s a risk of fractures and squeaks. However, the manufacturer of this bearing surface claims these negative factors have been resolved. The belief is that today’s ceramic-on-ceramic bearing surfaces are made from small grains, which ensure cohesiveness and a reduction in fractures. In the 1990s, this type of bearing device was sometimes prone to fractures because of its construction from large grains.
One of the disadvantages to the ceramic option is the limit in size—both in the size of the head and in the length.
What’s right for me?
The three types of implant options don’t seem to present a clear-cut leader. However, each manufacturer claims its type of replacement joint is the best and has fewer problems than its competitors.
In most cases, the first generation of testing surgeons are those who have a financial interest in the success of new components. Therefore, it’s no surprise that the initial studies show “great” results and the new implants are promoted as “forever hips.” The truth is the current studies are based on short-term and mid-term use (up to about five to seven years).
The second generation of testing physicians are orthopedic surgeons who don’t have a vested interest in the implants’ success and are using them in their day-to-day patient care. The most recent studies (from professional journals) are showing excellent results at mid-term follow-up.
Because it’s impossible to predict long-term success, it takes years of observation and studies to determine the actual lifespan of a new component. There aren’t yet studies that demonstrate long-term use (10 to 15 years) of these newer components, so the jury is still out on which implant offers the best results. The bottom line is patients need to evaluate the studies and choose an orthopedic surgeon they trust to recommend the most appropriate option.
Choosing an Orthopedist
Oddly enough, some people spend more time researching a new hair stylist than a surgical specialist. In addition to asking your primary care physician for a referral to an orthopedic surgeon, there are a few other things you can do to ensure a good “fit” for you or a family member.
Ask friends and family members about their experiences with any local orthopedic surgeons. During your initial appointment with a new surgeon (or physician of any type), be sure you feel comfortable with the interaction you have. Does she listen to you? Does she clearly explain your options? Because there are several different types of implants and techniques used for joint replacement, be sure your physician is knowledgeable about all of the options available so she can recommend what is appropriate for your condition, lifestyle, and needs.
Fortunately, today’s technology gives us more options to provide patients with the best care possible so they can get back to the activities they enjoy. TPW