Knee Replacement FAQs
- How will I know if I need a knee replaced?
- How do I know if I am a candidate for a partial knee replacement?
- Even if I am a candidate for a partial knee replacement, why not have the whole knee replaced instead?
- If I cannot have a partial knee replacement, am I a candidate for a total knee replacement?
- If I have had a partial knee replacement will I eventually need a total knee replacement?
- Can I have a total knee replacement once I've had a partial knee replacement?
- Can I have both knees replaced at the same time? Are two partial knee replacements ever done simultaneously?
- Why do I need dental clearance before surgery?
- What happens to the knee to cause it to become unstable or arthritic?
- If I have arthritis in one knee, will I also develop arthritis in the other knee?
- What materials does a knee replacement consist of?
- What does total knee replacement surgery entail? I'm worried about anesthesia. What do I need to know?
- How long is recuperation and rehabilitation after a total knee implant?
- I walk hills and stairs for exercise. Can I continue these activities after a knee replacement? How about yoga?
- Is there any activity I will not be able to do with a partial or total knee replacement?
- Will I be aware of the implant in my knee?
- How long will the implant last?
- Has there been a change over the years in who is having a partial or total knee replacement?
- Will I be able to go through the metal detector at airports?
- What happens if I get an infection in my new knee?
- I have heard that the device can loosen and that I will have to have another surgery to fix it. Is this true?
- Can I have an MRI if I have had a joint replaced?
1. How will I know if I need a knee replaced?
Often the first clues are pain, instability and loss of flexibility in the knee joint. The arthritic process that renders the knee painful and unstable occurs over time and may have been precipitated by trauma, a tear to the meniscus (cartilage) or a condition called avascular necrosis (dead tissue) in the bone. Knee injuries, often occurring decades in the past, may have resulted from a work-related event, contact or other sports, an automobile accident or from juvenile rheumatoid arthritis.
2. How do I know if I am a candidate for a partial knee replacement?
Candidates for partial knee replacements are adults, 40 to 60 years of age, who are in good health and who have exhausted conservative means for managing arthritic pain, such as medications, braces or putting a limit on activities. These patients have degeneration or arthritis on one side of the knee only. In the general population, about 10 percent of patients are candidates for this surgery.
3. Even if I am a candidate for a partial knee replacement, why not have the whole knee replaced instead?
If you are a candidate for a partial knee replacement, there are many advantages to having this surgery instead of a total knee replacement. First, many of your natural tissues, including the majority of the joint surface, cartilage and knee ligaments, are retained during partial knee replacement surgery. This helps you recover faster and shortens your rehabilitation time. Studies show that over a 10-year period and longer, a partial knee implant is still functioning in 90 percent of patients.
If you eventually needs a total knee replacement in the knee that had the partial knee implant, a revision surgery can be done. Studies show few complications with this second surgery.
4. If I cannot have a partial knee replacement, am I a candidate for a total knee replacement?
If you have significant degeneration in your knee as seen on imaging studies (X-rays, etc.) and you are experiencing pain and restricted movement, more than likely you are a candidate for a total knee replacement.
5. If I have had a partial knee replacement will I eventually need a total knee replacement?
No. The two are not mutually inclusive. Your partial knee replacement helps to re-stabilize the knee and may last a lifetime. Some patients, however, do experience more degeneration in the knee and may opt to have the knee totally replaced. In this instance, the whole knee, including the partial knee implant, is replaced.
6. Can I have a total knee replacement once I've had a partial knee replacement?
Yes. In this instance, all of the knee joint, including the previously implanted partial knee, are removed and replaced with the new implant.
7. Can I have both knees replaced at the same time? Are two partial knee replacements ever done simultaneously?
Yes. Virginia Mason orthopedic surgeons routinely perform what is called a bilateral knee replacement of both knees. This procedure can even be performed simultaneously by two surgical teams and in most instances does not increase the average surgical time (one to two hours). Two partial knee replacements are rarely done at the same time, primarily because most patients who qualify for this procedure have wear on one side of the knee only and only in one knee. However, if a patient becomes a candidate for a partial knee replacement of the other knee, that procedure certainly can be done.
8. Why do I need dental clearance before surgery?
All patients having joint replacement surgery, as well as patients having heart valve replacement surgery, must have clearance from their dentists showing that there is no infection, such as an abscessed tooth, in the mouth. The reason is that infection in one part of the body can travel to the new joint or valve and cause infection in these newly replaced parts.
9. What happens to the knee to cause it to become unstable or arthritic?
Our knees absorb quite a bit of shock over the course of our lifetimes and can begin to show wear and tear on the surface of bone and in the cartilage that sits between bones. Some medical conditions — inflammation or rheumatoid arthritis — also can cause this same type of degeneration. Additionally, direct injury to the knee joint from contact sports or accidents can destabilize the knee and cause uneven wear, eventually leading to arthritis later in life.
10. If I have arthritis in one knee, will I also develop arthritis in the other knee?
We have found that about 40 percent of patients with arthritis in one knee will also develop arthritis in the other knee. But having arthritis in one knee does not necessarily mean that arthritis will develop in your other knee.
11. What materials does a knee replacement consist of?
Knee replacement devices are comprised of cobalt-chrome alloy, titanium alloy and polyethylene plastic. A partial knee replacement is quite small. A total knee replacement is the same size as the actual knee. Other materials such as ceramics have been used but do not seem to be an advantage.
12. What does total knee replacement surgery entail? I'm worried about anesthesia. What do I need to know?
A total knee replacement is a major surgical procedure performed in the operating room. During this operation, your surgeon removes damaged bone and cartilage, resurfaces the top and bottom of your leg bones that meet to form the knee joint, and resurfaces the underside of the knee cap. Virginia Mason has one of the best anesthesia programs in the country and we specialize in regional anesthesia. You will be well cared for during your operation by your anesthesiologist.
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13. How long is recuperation and rehabilitation after a total knee implant?
Your recuperation and rehabilitation begins while you are still in the hospital and often on the same day as your surgery. A physical therapist will help you sit on the side of your bed and will also show you light exercises to do while in bed.
14. I walk hills and stairs for exercise. Can I continue these activities after a knee replacement? How about yoga?
There are very few restrictions after successful total knee replacement surgery. Walking, swimming, golf, biking, yoga, low-impact or water aerobics, cross-country skiing, and low-resistance weight training are all examples of very reasonable activities to pursue after knee replacement surgery.
15. Is there any activity I will not be able to do with a partial or total knee replacement?
It is not advisable to take part in repetitive high impact activities such as running or jogging. On the other hand, if you were already an expert downhill snow skier, you might return to skiing but will be advised to avoid the more high-impact aspects of the sport.
16. Will I be aware of the implant in my knee?
Usually not. Some patients will note the occasional tapping of the artificial implant surfaces against each other but, in general, the joint returns to feeling like a natural knee.
However, the knee replacement only replaces the surfaces of the joint. The new surfaces will eliminate pain and stiffness associated with those surfaces only. If there has been scaring or damage to the muscles and tendons around the joint from previous surgery or injury, these structures can cause continued stiffness and pain just as they would around a normal natural joint.
17. How long will the implant last?
The answer depends on the type of implant you have had and must take into account several factors, such as your age, physical condition, body weight and activity level. Because these devices are made with stronger materials today and provide a secure fit, a partial knee implant is expected to last beyond 10 years. A total knee replacement can last more than 30 years.
18. Has there been a change over the years in who is having a partial or total knee replacement?
Yes. Women are more active, so we are seeing more of them having partial and total knee replacement surgeries, and at younger ages. We do expect — with the aging of the population and higher activity levels of some "baby boomers" — that more people will require knee replacements in the near future.
19. Will I be able to go through the metal detector at airports?
Yes. You will be able to go through a metal detector. Some metal detectors are more sensitive than others and you may set off the alarm.
20. What happens if I get an infection in my new knee?
A deep infection in an artificial knee replacement is a very serious complication. It usually requires the complete removal of the implant before the infection can be cured. During the time the implant is gone and the patient is being treated with powerful antibiotics, a temporary antibiotic-soaked cement implant is often used to maintain joint spacing and motion. After the infection is gone a new knee replacement can be put in.
21. I have heard that the device can loosen and that I will have to have another surgery to fix it. Is this true?
Loosening of implants can occur and would require a replacement operation. Fortunately, with today's knee replacement designs, this has become rare.