Types Of Knee Implants
There are multiple types of knee implants that doctors and patients can discuss before choosing the best option.
Regardless of type, all knee implants have certain things in common.
All consist of a component that attaches to the thigh bone and one that attaches to the tibia, one of the two lower leg bones. A knee replacement implant may or may not have a patellar component mimicking the kneecap.
Some components, particularly the bearings, may be made of ceramics or a mixture of ceramics and metal. The materials have to be biocompatible meaning they cannot trigger the bodys rejection response. Knee implants are relatively lightweight usually between 15 and 20 ounces.
Why Have Knee Replacement Surgery
There are three common reasons for the procedure:
Osteoarthritis: this type of arthritis is age related, caused by the normal wear and tear of the knee joint. It mostly affects patients aged over 50 years, but younger people may have it.
Osteoarthritis is caused by inflammation, breakdown, and the gradual and eventual loss of cartilage in the joints. Over time, the cartilage wears down and the bones rub together. To compensate, the bones often grow thicker, but this results in more friction and more pain.
Rheumatoid arthritis: also called inflammatory arthritis, the membrane around the knee joint to become thick and inflamed. Chronic inflammation damages the cartilage, causing soreness and stiffness.
Post-traumatic arthritis: this type of arthritis is due to a severe knee injury. When the bones around the knee break or the ligaments tear, this will affect the knee cartilage.
Conditions That Can Be Treated With Knee Replacement
Knee replacement can be used to replace a knee joint affected by a range of conditions including:
- Severe osteoarthritis
- Ligament damage or infection that leads to severe osteoarthritis
- Rheumatoid arthritis
- Crystal deposition diseases such as gout and pseudogout
- Avascular necrosis death of bone following loss of blood supply
- Bone dysplasias disorders of the growth of bone.
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Technical Details Of Total Knee Replacement
Total knee replacement surgery begins by performing a sterile preparation of the skin over the knee to prevent infection. This is followed by inflation of a tourniquet to prevent blood loss during the operation.
Next, a well-positioned skin incision–typically 6-7 in length though this varies with the patients size and the complexity of the knee problem–is made down the front of the knee and the knee joint is inspected.
Next, specialized alignment rods and cutting jigs are used to remove enough bone from the end of the femur , the top of the tibia , and the underside of the patella to allow placement of the joint replacement implants. Proper sizing and alignment of the implants, as well as balancing of the knee ligaments, all are critical for normal post-operative function and good pain relief. Again, these steps are complex and considerable experience in total knee replacement is required in order to make sure they are done reliably, case after case. Provisional implant components are placed without bone cement to make sure they fit well against the bones and are well aligned. At this time, good function–including full flexion , extension , and ligament balance–is verified.
Finally, the bone is cleaned using saline solution and the joint replacement components are cemented into place using polymethylmethacrylate bone cement. The surgical incision is closed using stitches and staples.
Length of total knee replacement surgery
Pain and pain management
Implanting The Tibial Component
The bottom portion of the implant, called the tibial tray, is fitted to the tibia and secured into place using bone cement. Once the tray is in place, the surgeon will snap in a polyethylene insert to sit between the tibial tray and the femoral component, and act as a kind of buffer. This insert will provide support for your body as you bend and flex your knee.
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Knee Replacement Recovery Time And Recuperation
Total knee replacement surgery generally takes about 60 to 90 minutes, but you should expect to be in the operating room for over two hours. Rehabilitation will begin within 24 hours of surgery.
After your surgery, the nursing staff will position you in bed and help you turn until you are able to move on your own. You may have a pillow between your legs if ordered by your surgeon.
Very soon after surgery, a physical therapist will come to your room to teach you appropriate exercises and review your progress. Gentle exercises to improve your range of motion can help prevent circulation problems as well as strengthen your muscles.
Your rehabilitation program will begin as soon as you are medically stable and there are orders from your doctor to begin postoperative mobility. All patients begin rehabilitation within 24 hours of their surgery. Your motivation and participation in your physical therapy program is key to the success of your surgery and recovery. The physical therapist will assist you in the following activities:
- sitting at bedside with your feet on the floor
- transferring in and out of bed safely
- walking with the aid of a device
- climbing stairs with aid of a device
Why Is My Knee So Tight After Surgery
Arthrofibrosis is also known as stiff knee syndrome. The condition sometimes occurs in a knee joint that has recently been injured. It can also occur after surgery on the knee, such as a knee replacement. Over time, scar tissue builds up inside the knee, causing the knee joint to shrink and tighten.
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What Is The Benefit Of Patellofemoral Knee Replacement Vs Total Knee Replacement
One of the main benefits of patellofemoral joint replacement over total knee replacement is that the knee ligaments are not cut to access the compartment to be replaced. This can make the knee joint move more naturally with better range of motion. The quadriceps tendon is also not cut. Compared to replacing the entire knee, patellofemoral joint replacement has a shorter recovery time, involves less blood loss and pain, and better knee function.
There is some evidence from a 2018 review that long-term function with patellofemoral knee joint replacement is less than a total . However, there are a variety of possible factors underlying the difference, including patient characteristics, surgical expertise, and type of implant, among others.
Ask your doctor what makes you a good candidate for kneecap replacement.
Will I Be Able To Get Back To A Physical Active Lifestyle
Urquhart: Most patients about 80 to 85% feel their knee functions better than before they had surgery. These patients can get back to low-impact physical activity, such as walking, hiking, biking, playing golf or tennis and other light recreational activities. We discourage high-impact activities, such as basketball and running, as these can reinjure the knee.
To make a consultation appointment with our Comprehensive Musculoskeletal Center team, please visit the CMC website.
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Posterior Cruciate Ligament Retaining
The posterior cruciate ligament runs along the back of the knee, connecting the femur to the tibia. This design keeps the PCL intact, but it depends on several patient factors: good bone quality, few defects in the bones, intact soft tissue around the knee and a functional PCL.
There are two types of PCL implants: retaining and substituting. The difference between the two comes in part from how the PCL is affected by the implant surgery. A surgeon may remove the ligament to implant a PCL substituting implant. But if the ligaments are in good condition, the surgeon may want to preserve it. In that case, he or she will use a PCL retaining implant.
Preserving the ligament may not necessarily result in better post-operative knee function. A simple polyethylene bearing attaches to a metal component implanted in the tibia, and a metal implant in the femur hinges on the polyethylene. It is a minimal design dependent on the PCL to stabilize the implant but a tight PCL may lead to excessive wear on the bearing.
Less bone is removed with a PCL retaining implant. A PCL retaining implant is less likely than a PCL substituting version to result in a condition called patella clunk syndrome. This syndrome results from scar tissue forming near the implant and becoming caught in part of the device as the knee is fully extended.
Complex Or Revision Knee Replacement
This procedure is done when the original knee replacement surgery has either failed or has reached the end of its useful life. Sometimes, an artificial joint can become infected necessitating removal and replacement of the implanted components. Another reason for a revision knee replacement is a fracture of the bone in the area of an implant component. A revision knee replacement procedure is more complicated as the knee has previously been surgically altered. Specialized implants need to be used, and there is a lot more planning involved for this procedure. Often these implants have thicker stems that fit deeper into the bones of the femur and tibia.
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Types Of Arthritis That Affect The Knee
This broad category includes a wide variety of diagnoses including rheumatoid arthritis, lupus, gout and many others. It is important that patients with these conditions be followed by a qualified rheumatologist as there are a number of exciting new treatments that may decrease the symptoms and perhaps even slow the progression of knee joint damage.
Patients with inflammatory arthritis of the knee usually have joint damage in all three compartments and therefore are not good candidates for partial knee replacement. However, inflammatory arthritis patients who decide to have total knee replacement have an extremely high likelihood of success. These patients often experience total, or near-total, pain relief following a well-performed joint replacement.
Osteoarthritis is also called OA or degenerative joint disease. OA patients represent the large majority of arthritis sufferers. OA may affect multiple joints or it may be localized to the involved knee. Activity limitations due to pain are the hallmarks of this disease.
OA patients who have symptoms limited to one compartment of the knee sometimes are good candidates for minimally-invasive partial knee replacement .
Ial Vs Total Knee Replacement Surgery: What You Need To Know
Are you part of the .2%? Each year, thousands of people in the United States have knee replacement surgery about 600,000 to be exact, according to the Agency for Healthcare Research and Quality. Robert L. DeMaagd, MD, specialist with the Total Joint Center at Orthopaedic Associates of Michigan, sees his fair share. I do close to 300 knee replacements each year, says Dr. DeMaagd. That includes both partial and total replacements.
Who is a candidate for knee replacement? According to Dr. DeMaagd, most knee replacement patients are between 55-75 years old. Typically knee replacement surgery is done for chronic osteoarthritis of the knee joint that has not been successfully treated with non-operative means like medication, bracing, injections, and physical therapy, he explains. Arthritis is an inherited trait, so for most people, its just a genetic wearing out of the joint.
Time to move on Many of these non-operative treatments can be good for mild to moderate arthritis, and you can go for years without joint replacement surgery, Dr. DeMaagd says. But after a while, those measures just dont work. You have to move on to something else. Thats when patients typically contact OAM. If the knee pain and stiffness are affecting a patients quality of life or getting in the way of normal daily activity, the patient is probably a good candidate for a knee replacement, says Dr. DeMaagd.
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Who Should Consider Total Knee Replacement Surgery
It is usually reasonable to try a number of non-operative interventions before considering knee replacement surgery of any type. Prior to surgery an orthopedic surgeon may offer medications knee injections or exercises. A surgeon may talk to patients about activity modification weight loss or use of a cane.
The decision to undergo the total knee replacement is a “quality of life” choice. Patients typically have the procedure when they find themselves avoiding activities that they used to enjoy because of knee pain. When basic activities of daily life–like walking shopping or reasonable recreational pastimes–are inhibited or prevented by the knee pain it may be reasonable to consider the surgery.
Ial Vs Total Knee Replacement
While in total knee replacement all the compartments of the knee joint are usually replaced, a partial knee replacement only involves the replacement of a single knee compartment.
The knee joint is divided into three compartments or spaces. The joint is formed by the lower end of the thigh bone, the upper part of the shinbone, and the undersurface of the kneecap.
The inner side of the knee is called the medial compartment, and similarly, the outer side of the knee forms the lateral compartment. In front of the knee, the joint formed by the kneecap and the thigh bone forms the patellofemoral compartment.
X-ray showing a partial knee replacement.
The bones forming the knee joint are covered with a glistening white tough tissue known as articular cartilage. The articular cartilage helps in the smooth gliding of the joint in motion. Various ligaments, meniscus, and muscles provide additional stability to the knee joint.
Majority of the patients who may need joint replacement surgery suffer from osteoarthritis. Osteoarthritis is a wear and tear disease of the joint that gradually destroys the articular cartilage, the bone ends, and the ligaments secondary to instability. Arthritis may affect all the compartments at the same time or may start in one of the compartments first.
Partial knee replacement
Partial vs Total Knee
X-ray showing a total knee replacement.
Dr. Suhirad Khokhar
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Can Rehabilitation Be Done At Home
All patients are given a set of home exercises to do between supervised physical therapy sessions and the home exercises make up an important part of the recovery process. However, supervised therapy–which is best done in an outpatient physical therapy studio–is extremely helpful and those patients who are able to attend outpatient therapy are encouraged to do so.
For patients who are unable to attend outpatient physical therapy, home physical therapy is arranged.
What Is Total Knee Replacement
Total knee replacements are one of the most successful procedures in all of medicine. According to the Agency for Healthcare Research and Quality, more than 790,000 knee replacements are performed each year in the United States. What exactly is a Total Knee Replacement? What does the surgeon put in my body during knee replacement? Is there a lot of leg bone removed in Total Knee Replacement?
In this week’s vlog, Dr. Calendine offers a practical, patient-centered explanation of Total Knee Replacement surgery. Dr. Calendine answers the questions above, and more, as he carefully walks you through the main components of Total Knee Replacement.
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Common And Serious Complications Of Knee Replacement
While knee implants give many recipients a second chance at walking and living a more normal life, complications do occur.
Most problematic is a loosening of the implant, which can be caused by a defective implant or poor positioning at the time of surgery. Implant loosening is a primary cause for revision surgery.
Although rare, metallosis is possible after knee replacement surgery. Metallosis, also known as metal poisoning, can occur when metal implant pieces rub against each other and release tiny metal particles into the knee joint and bloodstream.
Common complications from knee surgery include:
- Swelling and stiffness
Who Might Need A Knee Replacement
Knee surgery may be suitable for patients who experience:
- Severe knee pain or stiffness that prevents them from carrying out everyday tasks and activities, such as walking, going upstairs, getting in and out of cars, getting up from a chair
- Moderate but continuous knee pain that continues while sleeping or resting
- Chronic knee inflammation and swelling that does not improve after taking medications or resting
- Knee deformity, where there is a noticeable arch on the inside or outside of the knee
- Depression, resulting from an inability to carry out daily or social activities
If the other available treatment options have not worked, surgery may be the best option.
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Injuries And Problems Of The Knee Joint
The knee joint is vulnerable to stresses, traumatic injury, overuse, and arthritis. The articular cartilage in the knee can be damaged by disease, injury, or normal wear and tear over time. When the cartilage is damaged, the joint surfaces may no longer be smooth. Moving bones along a rough, damaged joint surface is difficult and causes pain. Damaged cartilage can also lead to arthritis in the joint. Articular cartilage does not heal itself well, so sometimes surgical intervention is required. Also, damage to the shock absorbing meniscus, tendons, and ligaments can occur. This is common in traumatic injuries such as in sports, but also in falls. When the knee is not able to properly support the weight of the body, joint damage and arthritis can occur. Often, when there is pain and dysfunction, you will hear that the knee joint is bone on bone. This means that the articular cartilage and the meniscus have become damaged, and there is no more friction reduction or shock absorption in the knee. Additionally, certain conditions such as infections or diseases such as rheumatoid arthritis and avascular necrosis can lead to damage in the knee joint. Conditions like these may require surgical intervention to restore pain-free function of the knee joint.