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What Does An Artificial Knee Look Like

Physical Therapy Guide To Total Knee Replacement

How does an artificial joint look like & what is it made of? – Dr. V G Rajan

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The knee is the most commonly replaced joint in the body. The decision to have knee replacement surgery is one that you should make in consultation with your orthopedic surgeon and your physical therapist. Usually, total knee replacement surgery is performed when people have:

  • Knee joint damage due to osteoarthritis, rheumatoid arthritis, other bone diseases, or fracture that has not responded to more conservative treatment options
  • Knee pain or alignment problems in the leg that cause difficulty with walking or performing daily activities, which have not responded to more conservative treatment options

Physical therapists are movement experts who improve quality of life through hands-on care, patient education, and prescribed movement. You can contact a physical therapist directly for an evaluation. To locate a physical therapist in your area, visit Find a PT.

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.

Your Knee Is Always Swollen

Swelling is another sign your knee is not responding to other treatments.

A knee that is consistently swollen despite the use of anti-inflammatory medications, steroid injections and physical therapy suggests degeneration of the cartilage and/or instability of the knee, which can be confirmed with an X-ray, Lieberman explains. This can make you a candidate for a total knee replacement, he says.

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How Is A Total Knee Replacement Performed

First, the orthopedic surgeon makes an incision in the knee and moves the patella to the side. If are any bone spurs are present, as sometimes occurs in osteoarthritis, they will be removed.

Next, the two menisci between the femur and tibia are removed, as are the anterior cruciate ligament and, in some cases, the posterior cruciate ligament . In some types of knee replacement, the PCL is retained.

During the main phase of the operation, the surgeon cuts and remove cartilage and some bone from the upper part of the tibia and lower sections of the femur. The femoral sections removed are two knobby protuberances called the femoral condyles. The tibia and femur are then be capped with metal implants to create new surfaces for the joint. The surface of the femoral component mimics the shape of the original femoral condyles. If the kneecap has also degraded, the surface on its underside may also be cut away and replaced with a polyethylene implant.

Finally, the various layers of tissue are repaired with dissolvable sutures and the skin incision is closed with sutures or surgical staples. A bandage will be wrapped around the knee and the patient is be taken to recovery.

Fixed-bearing knee implant with a polyethylene articulating surface sandwiched between the metal tibial implant and metal femoral implant.

Side-view illustration of a knee with a fixed-bearing knee implant in place.

X-ray of a knee after total knee replacement, showing the implanted prosthesis)

Are There Any Reasons Why I Cant Have A Knee Replacement

Total Knee Replacement

Unfortunately, some people may not be able to have a knee replacement even though their arthritis is very bad. This may be because:

  • your thigh muscles are very weak and may not be able to support your new knee joint
  • there are deep or long-lasting open sores in the skin below your knee, increasing your risk of infection.

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Types Of Knee Implants

Thinking about a total knee replacement? There are a few different kinds of knee implants that are used in this procedure. The different types are categorized by the materials that rub against each other when you flex your knee:

Metal on plastic. This is the most common type of implant. It features a metal femoral component that rides on a polyethylene plastic spacer attached to the tibial component. The metals commonly used include cobalt-chromium, titanium, zirconium, and nickel. Metal-on-plastic is the least expensive type of implant and has the longest track record for safety and implant life span. However, one problem that can happen with plastic implants is an immune reaction triggered by tiny particles that wear away from the spacer. This can cause bone to break down, leading to loosening and failure of the implant. Advances in manufacturing have greatly reduced the rate of wear in the plastic.

Ceramic on plastic. This type uses a ceramic femoral component instead of metal . It also rides on a plastic spacer. People who are sensitive to the nickel used in metal implants might get the ceramic type. Plastic particles from this type of implant also can lead to an immune reaction.

To learn more about your options for knee replacement surgery, read the Harvard Medical School guide Total Knee Replacement.

Why The Procedure Is Performed

The most common reason to have a knee joint replaced is to relieve severe arthritis pain. Your doctor may recommend knee joint replacement if:

  • You are having pain from knee arthritis that keeps you from sleeping or doing normal activities.
  • You cannot walk and take care of yourself.
  • Your knee pain has not improved with other treatment.
  • You understand what surgery and recovery will be like.

Most of the time, knee joint replacement is done in people age 60 and older. Younger people who have a knee joint replaced may put extra stress on the artificial knee and cause it to wear out early and not last as long.

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Total Knee Replacements Can Fail By A Number Of Mechanisms Says Orthopedic Surgeon David Fisher Md Director Of The Total Joint Center At The Indiana Orthopedic Hospital

There are five chief reasons for a failed TKR. Unfortunately, the first one that Dr. Fisher mentions brings to mind the concept of surgeon error.

He states, In some cases, they were not implanted in a way that creates a well-functioning knee, and the patients are never happy with them. This is one of the more common causes of revision knee replacement.

Its deeply troubling that surgeon error cannot be proven, as the defense will blame the manufacturer of the hardware and/or loosening of the cement over time.

Dr. Fisher continues, Another common reason is an infection develops postoperatively and leads to a need for revision.

This may occur in 0.1-2% of knees and may be related to the volume of the operating surgeon and the hospital in which the surgery was performed.

Following knee replacement or revision surgery, patients will get their temperature taken as often as once every four hours, and this includes overnight, to check for signs of an infection.

Late infections can develop occasionally many years after implantation, says Dr. Fisher.

The first signs of an infection may be warmth and redness about the knee.

Loosening of the prosthesis rarely occurs in the first few years but can be a cause of late failure and will usually be associated with pain and swelling.

The final mechanism behind a failed TKR: Polyethylene wear can also occur many years after implantation and cause symptoms of pain and swelling.

How Do I Determine If I Need A Knee Replacement

Artificial Knee Replacement

If youre considering knee replacement surgery, talk to an orthopedic surgeon. Orthopedic surgeons specialize in operations to fix joints and muscles.

Your orthopedic surgeon will:

  • Ask about your symptoms, including how severe they are and how long youve had them. The surgeon may also ask whether anything makes symptoms better or worse, or whether symptoms interfere with your daily life.
  • Take your medical history to learn about your overall health.
  • Examine you to check knee motion, strength and stability.
  • Order X-rays of your knee. The images can help the surgeon understand how much damage is in your knee. Advanced imaging is rarely helpful in the arthritic knee.

The orthopedic surgeon will then make a recommendation for surgery or another treatment option.

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When Can I Get Back To My Everyday Activities After Knee Arthroplasty

Your doctor will give you specific instructions. But many people can get back to their everyday activities three to six weeks after surgery.

Your healthcare provider will give you specific instructions about recovery. You will gradually increase activity, starting with a slow walking program. You will be encouraged to stand, climb stairs and perform other normal household activities as soon as possible.

Posterior Cruciate Ligament Substituting

This design replaces ligament with plastic components. It is recommended primarily for patients with severely damaged knees or weak ligaments. Also used in revision surgery.

It is indicated for patients with severe knee deformities or who have had previous knee replacement surgery or have had a knee cap removed.

The PLC substituting design has a tall post attached to the tibia which fits into a deep box attached to the femur. The two are not connected with any kind of hinge joint. A polyethylene bearing attaches to the tibial component.

A 2016 study of the PLC substituting design found that 88.5 percent of PLC substituting implants used in initial knee replacement surgery survived 10 years. For revision surgery, the 10 year survival rate was 75.8 percent if the revision surgery was due to some cause other than infection, and 54.6 percent if revision was due to infection.

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Outlook For Knee Replacement

While some activities are off-limits after a knee replacement, you still have plenty of others to choose from. Unlimited walking, golf, light hiking, cycling, ballroom dancing, and swimming are all safe for most people with knee implants. By following your doctor’s guidelines, you can expect long-lasting results — about 85% of knee replacements will last 20 years.

Common And Serious Complications Of Knee Replacement

Total Knee Replacement for Osteoarthritis: Benefits and ...

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
  • Centers for Disease Control and Prevention. . Arthritis-Related Statistics. Retrieved from
  • American Academy of Orthopaedic Surgeons. . Total Knee Replacement. Retrieved from
  • Orthogate. . Revision Arthroplasty of the Knee. Retrieved from
  • Bonesmart. . Reasons for Knee Replacement Surgery. Retrieved from
  • American Academy of Orthopaedic Surgeons. . Knee Replacement Implants. Retrieved from
  • Your Practice Online. Revision Knee Replacement. Retrieved from
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    As You Begin To Recover

    The goal of the first 2 weeks of recovery is to manage pain, decrease swelling, heal the incision, restore normal walking, and initiate exercise. Following those 2 weeks, your physical therapist will tailor your range-of-motion exercises, progressive muscle-strengthening exercises, body awareness and balance training, functional training, and activity-specific training to address your specific goals and get you back to the activities you love!

    Range-of-motion exercises. Swelling and pain can make you move your knee less. Your physical therapist can teach you safe and effective exercises to restore movement to your knee, so that you can perform your daily activities.

    Strengthening exercises. Weakness of the muscles of the thigh and lower leg could make you need to still use a cane when walking, even after you no longer need a walker or crutches. Your physical therapist can determine which strengthening exercises are right for you.

    Body awareness and balance training. Specialized training exercises help your muscles “learn” to respond to changes in your world, such as uneven sidewalks or rocky ground. When you are able to put your full weight on your knee without pain, your physical therapist may add agility exercises and activities using a balance board that challenge your balance and knee control. Your program will be based on the physical therapists examination of your knee, on your goals, and on your activity level and general health.

    Whats The Difference Between Partial Knee Replacement And Total Knee Replacement Ive Also Heard Of Resurfacing The Knee What Does That Mean

    Urquhart: A partial knee replacement is performed on patients who have intact ligaments and pain isolated to the inside portion of the knee. Performing surgery on that inside portion of the knee, called the medial compartment, can result in relief of symptoms and the patient not needing surgery on the entire knee joint, thus the partial title.

    All knee replacement surgeries involve some amount of resurfacing, or replacement of the knees cartilage. Patients usually hear about resurfacing for hips, which is a type of total hip replacement surgery. At Michigan Medicine, we dont currently recommend hip resurfacing for a variety of reasons and encourage patients who need surgery to have a stemmed total hip replacement with implants that have a good registry track record instead.

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    Can This Injury Or Condition Be Prevented

    If you have knee pain, you may be able to delay the need for surgery by working with a physical therapist to improve the strength and flexibility of the muscles that support and move the knee. This training could even help you avoid surgery altogether. Participating in an exercise program designed by a physical therapist can be one of your best protections against knee injury. And staying physically active in moderately intense physical activities and controlling your weight through proper diet might help reduce the risk of osteoarthritis of the knee getting worse.

    Am I A Candidate For Total Knee Replacement

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    Urquhart: I always start by telling patients that total knee replacement surgery shouldnt be thought of as the only way to treat knee pain.

    Patients who can walk on level ground without much difficulty, or who only have pain when going up and down stairs, are not good candidates for knee replacement surgery. Patients in their fifties or older who have a hard time walking, despite trying non-surgical treatments first, may be good candidates for knee replacement surgery.

    Before considering knee replacement surgery, I always recommend patients start with improving their diet and exercise routine. Many Americans are overweight and just losing a few pounds can improve symptoms in the knee, which carries five times a persons body weight when going up a single stair. Targeted physical therapy and exercise can improve and strengthen the muscles in the knee, which may result in less pain symptoms.

    We also recommend patients try non-steroidal medications such as ibuprofen or acetaminophen to reduce swelling and pain. For some patients, we recommend trying steroid injections, such as cortisone injections, before electing knee replacement surgery.

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    Who Is A Candidate For Partial Knee Replacement

    People with medial, or lateral, knee osteoarthritis can be considered for partial knee replacement. “Medial” refers to the inside compartment of the joint, which is the compartment nearest the opposite knee, while “lateral” refers to the outside compartment farthest from the opposite knee. Medial knee joint degeneration is the most common deformity of arthritis.

    Other factors to consider:

    • You may want to consider a knee replacement if your knee pain persists despite your taking anti-inflammatory drugs and maintaining a healthy weight.
    • Your provider will ask you to identify the area of pain in your knee, then check your range of motion and the knee’s stability. An X-ray of the knee will determine your eligibility for partial knee replacement. However, your surgeon may not know for certain if you are a good candidate until the surgery has begun.
    • You must have an intact anterior cruciate ligament, a sufficient range of knee motion, damage to only one compartment and a stable knee. The angulation of the deformity is also considered.
    • In the past, a partial knee replacement was considered only in people 60 and over who were sedentary. Now younger, more active people are increasingly being considered.

    Preoperative Planning And Timing Of Surgery

    Timing is dictated by the acuity of the infection. A chronic low-grade infection can often be dealt with on an urgent but not emergent basis. A fulminant acute infection should be addressed quickly, particularly if there is the risk of seeding other total joint arthroplasties or other prosthetic devices.

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    Learning To Live With Your New Knee

    Having a total knee replacement provides significant pain relief for more than 90 percent of people who have the surgery.

    It can take some time to get used to the new knee, so its important to understand what is normal during recovery and how having an artificial knee can affect your day-to-day life after surgery.

    Your new knee doesnt come with an owners manual, but recognizing potential issues and preparing for them can help maximize your quality of life after surgery.

    Its not unusual for your artificial knee to make some popping, clicking, or clunking sounds, particularly when you bend and extend it. This is most often normal, so you shouldnt be alarmed.

    Several factors can affect the likelihood of these noises or sensations after surgery, including the


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