Patient Education
 

Understanding Knee Replacement

National Orthopedics and Neurosurgery, PA in Florida

Unfortunately, the knees you’re born with don’t come with a lifetime warranty. When working properly, they give you decades of mobility and help you lift everything from groceries to grandchildren. But, as years pass, arthritis often sets in. It may start with an occasional ache or an uncanny ability to predict rain. At its worst, knee arthritis may prevent you from being active during the day and sleeping at night. That’s why you should know there’s help for knees in need.

Knee Arthritis
The knee is like a hinge that joins your thigh bone (femur) to your shin bone (tibia). Cartilage provides a cushion between the bones. Muscles and tendons connect them and keep the joint stable. When healthy, these parts work together to let you bend your knee smoothly and without pain.


Knee Arthritis

If your knees ache, they have lots of company. Over 46 million Americans suffer from arthritis.1 Osteoarthritis is the most common type, and the way it works in the knee is pretty simple. Three bones meet up at the knee joint: the end of the thigh bone (femur), the top of the shin bone (tibia), and the kneecap (patella). Those bones are cushioned by cartilage, but when the cartilage is injured or worn away—which is actually the definition of osteoarthritis—the bones grind against each other. That grinding hurts. You can feel it climbing stairs, working in the garden, or just bending your knees to sit. It may even keep you up at night.

Knee Arthritis

In an osteoarthritic knee, the cartilage has thinned and deteriorated, allowing bone to rub against bone and cause pain.


Why you?

Researchers are finding a strong link between genetics and osteoarthritis. In other words, if your mother had it, you’re more prone to have it too.2 Other contributing factors may be trauma to the knee, overuse on the job (think of those major league baseball catchers), or being overweight. In addition, osteoarthritis can occur when joints are out of alignment, as in people who are bowlegged or knock-kneed.

Diagnosis

In an osteoarthritic knee, the cartilage has thinned and deteriorated, allowing bone to rub against bone and cause pain.

Early diagnosis of arthritis and tailored treatment are crucial in slowing or preventing damage to your joints. Only a physician can determine if you have arthritis, based on:

the overall pattern of symptoms
medical history
physical exam
X-rays and other imaging techniques
lab tests

The good news about arthritis in the knee is that it can be treated. Here are some signs that it might be time to talk to your doctor:

Pain persists or recurs over time
Pain worsens after exercise or other weight-bearing activities
Pain in rainy weather
Pain prevents you from sleeping
A decrease in knee motion or the degree to which you’re able to bend your knee
Stiff or swollen knees
Difficulty walking or climbing stairs
Difficulty getting in and out of chairs and bathtubs
Morning stiffness that typically lasts less than 30 minutes (as opposed to stiffness lasting longer than 45 minutes, a sign of an inflammatory condition called rheumatoid arthritis)
“Grating” of the joint
Previous injury to the anterior cruciate ligament (ACL) of the knee

Nonsurgical Treatments

Arthritis is a disease that typically worsens over the years, so it is common for treatment to involve more than one approach and to change over time. For some people, the lifestyle changes, medications, and walking aids described on the next pages help alleviate the pain. For others, knee replacement surgery, which is discussed later in this booklet, may be the only long-term solution. Together, you and your doctor can determine the best treatment options for you.

The following nonsurgical treatments are often recommended for knee pain:

Did you know? For a perfect fit, the top of your cane’s handle should reach the crease of your wrist, when you are standing with arms at your side. The cane should be held in the hand opposite the painful knee.


Pacing Your Activities
helps protect your joints. This involves alternating periods of activity with periods of rest, so your joints don’t tire from the stress of repeated tasks.

Assistive Devices may help you maintain mobility, while easing joint stress and pain. For example, shoe inserts called orthotics are designed to support, align, and improve the function of your foot. In turn, they may lessen the pressure on your knees. A cane can also be very helpful (not to mention dapper).

Did you know? Many range-of-motion exercises and aerobic exercise programs, including fitness walking and swimming, are often beneficial for people with osteoarthritis. Strengthening of the quadriceps (thigh muscle) can help reduce knee pain caused by kneecap (patella) problems and several different kinds of ligament tears.


Low-Impact Exercise
is important to keep the body moving and flexible. And contrary to popular opinion, when done properly, it will not “wear out” joints or increase osteoarthritis.

Weight Loss reduces the stress on your knees and is beneficial for people in all stages of osteoarthritis. After all, your knees bear the full load of your weight plus everything you carry.

Bracing may help reduce knee pain and improve function and mobility. Different types of braces are available. For example, a “support” brace supports the entire load on your knee, but an “unloader” supports the weight on only one side, when only one side of the knee is damaged.

Did you know? Physical therapists can work with you to create a personalized exercise program and show you how to use therapeutic heat and massage. Occupational therapists can introduce you to all kinds of beneficial devices, such as those used to elevate chair or toilet seat height.


Heat or Cold
treatments may provide short-term relief from arthritic pain and stiffness. Using cold packs helps reduce inflammation and swelling and may be useful in flare-up situations. Heat assists in relaxing muscles and increasing circulation.

Physical & Occupational Therapy can help you manage the pain of osteoarthritis.

Medications are used by millions of people to treat osteoarthritis. They run the gamut from over-the-counter to prescription drugs, including aspirin-free pain relievers, anti-inflammatory drugs, corticosteroids, disease modifiers, and sleep medications. Nonnarcotic and narcotic pain relievers can also be used. However, some of these can be addictive over time.

Did you know? It is important to talk with your doctor about all medications and dietary supplements you are taking or are considering taking, even those available without a prescription. All drugs have side effects, and some of the medications used to treat osteoarthritis increase the risk of liver and kidney damage. Even nonprescription NSAIDs, such as ibuprofen and naproxen, have potential cardiovascular and gastrointestinal risks.


Primary care physicians often begin treating osteoarthritis with a simple pain reliever such as acetaminophen3 (Tylenol). If the pain persists, oral NSAIDs (nonsteroidal anti-inflammatory drugs) may be tried.

Injections of hyaluronic acid, a substance produced in natural, healthy joints, are sometimes used to provide temporary relief from knee pain. Anesthetics also may be injected with a corticosteroid (usually cortisone), to numb your knee and help keep pain at bay.

Nontraditional or Alternative Treatments are used by many people who suffer from knee osteoarthritis, although the effectiveness of these treatments is usually not supported by widely accepted scientific research. In addition, herbal and dietary supplements are not regulated by the FDA. Because drug interactions and side effects can occur, it is extremely important for you to consult with your physician about all supplements and medications that you are taking or considering taking.

Did you know? The National Institutes of Health (NIH) conducted a study called the Glucosamine/ Chondroitin Arthritis Intervention Trial (GAIT), the first multicenter study to test the effects of these dietary supplements in treating knee osteoarthritis. The study found that these supplements, when used in combination, may provide pain relief for people with moderate to severe knee osteoarthritis. People with mild osteoarthritis did not experience significant pain relief.


Minimally Invasive Knee Surgery

If nonsurgical treatments aren’t relieving your pain and your mobility is affected, you may still achieve the results you want with surgery on your knee. There are better surgical choices today than before.

Arthroscopy

Often the first surgical treatment for knee osteoarthritis is arthroscopy, a surgical procedure used to see, diagnose, and treat problems inside the joint. Arthroscopy typically involves inserting a small camera into the knee and then treating identifiable problems, which may include:

trimming damaged cartilage
removing loose debris within the knee (debridement)
irrigating the inside of the knee (lavage)
removing/repairing a torn meniscus (cartilage) or reconstructing a damaged ligament

Arthroscopy has been shown to diminish pain, and it may help delay the progression of knee osteoarthritis.

Is it time for knee replacement?

That’s a question you and your orthopedic surgeon will have to answer together. But when knee pain is so bad it actually interferes with the things you want or need to do, the time may be right. Here are some signs to consider:

Medication and using a cane just aren’t delivering enough relief
Pain is keeping you up at night
Your knee aches during and after exercise
Your knee stiffens up sitting in a car or a movie theater
You are no longer as mobile as you’d like to be

What is total knee replacement?

It’s the same idea as having most things fixed—worn parts are taken out, and new parts are installed in their place. In total knee replacement surgery, the damaged portions of the knee bones are removed, and the knee is resurfaced with metal and plastic implants. A National Institutes of Health (NIH) Consensus Panel concluded that total knee replacement is extremely successful, resulting in “rapid and substantial improvement in the patient’s pain, functional status, and overall health-related quality of life in about 90% of patients.”4 Over 250,000 people a year undergo the procedure, in the US alone.

What is partial knee replacement?

Partial knee replacement is an option for the patient whose knee is damaged on one side and healthy on the other. The surgeon removes only the diseased portion of the knee before placing the implant, leaving the healthy portion untouched. As with any surgery, there are risks, and only a surgeon will be able to tell you if a partial knee is right for you.

Did you know? Sometimes, partial knee replacement can be performed with minimally invasive surgery. Hospital time is minimized, and the procedure may even be done on an outpatient basis. Talk with your surgeon to find out if you are a candidate for minimally invasive surgery.


How long does knee replacement last?

That’s a question no one can answer for sure. The patient’s physical condition, activity level, and weight all play a role. With appropriate activity, knee replacements can last many years. Your individual outcome depends on many factors that you can discuss with your surgeon.

What risks are involved?

Every surgical procedure has some risks and benefits. Your individual results will depend on your personal circumstances, and recovery takes time. Infection is a risk in any surgical procedure, and according to the American Academy of Orthopaedic Surgeons, 1.8% of patients get an infection in the first 2 years. When infection occurs after total knee replacement, it is most commonly caused by bacteria that enter the bloodstream during dental procedures or from urinary tract, skin, or fingernail infections. Although uncommon, when these complications occur, they can delay full recovery. For the first 2 years after your knee replacement, you must take preventive antibiotics before dental or surgical procedures that could allow bacteria to enter your bloodstream. After 2 years, talk to your orthopedist and your dentist to see if you still need preventive antibiotics before other procedures.

Dislocation can result from improper positioning during surgery. Joint fracture has been reported following joint replacement and is typically caused by heavy weight or people with unrealistic performance expectations. How long a knee replacement will last varies from person to person. It depends on many factors, such as your physical condition and activity level, body weight, and the surgical technique.

Women Are Not Smaller Men! The Zimmer Gender Solutions™ Knee is the only knee replacement specifically designed with a woman’s shape in mind. There are three distinct differences from unisex implants:

1) The Zimmer Gender Knee has a thinner profile than traditional knee replacements
2) It allows for more natural movement of the kneecap
3) It has a shape specially contoured for women


Blood clots in the leg veins are the most common complication of knee replacement surgery. Your surgeon will outline a prevention program. This may include periodic elevation of your legs, lower leg exercises to increase circulation, support stockings, and medication to thin your blood.

How do I know which knee is right for me?

Knee replacements have been highly successful for more than 30 years. According to the National Institutes of Health, 9 out of 10 patients who undergo the procedure report improved pain relief, knee function, and overall health-related quality of life. It is important to be involved in your recovery, and there are some additional things about knee replacement you may wish to discuss with your primary doctor and an orthopedic surgeon:

Be flexible

Flexion, or bending, is an important subject when talking with your doctor about which knee replacement is right for you. Many everyday activities require good range of knee motion, such as climbing stairs (75-140 degrees) and sitting in a chair (90-130 degrees). Other activities, such as gardening, golfing, kneeling, or sitting cross-legged, can demand an even greater degree of bending. Zimmer was the first to develop several high-flex knee implants, including NexGen® and Gender Solutions Knees, which accommodate 155 degrees of deep-knee bending in patients who are able. Most other knee replacements accommodate knee bending only up to 125 degrees. Talk to your doctor about the risks that are associated with knee replacement.

Is it time for knee replacement?


Minimally Invasive Options

Traditional knee replacement surgery involves a long incision (8 to 12 inches) and a lengthy rehabilitation. Over the past decade, however, minimally invasive techniques have been developed to place the very same clinically proven joints. Today, there are even minimally invasive procedures for partial knee replacement. You and your surgeon can determine if you are a candidate for minimally invasive surgery.

Zimmer MIS Knee Replacement

Zimmer’s minimally invasive knee replacement techniques involve less cutting of skin than traditional surgery, and less or no cutting of key muscles and tissues. The goals of the Zimmer MIS techniques are to alleviate pain, restore mobility, and get you back to your everyday activities sooner.

Zimmer MIS procedures are named based on how your surgeon accesses your knee, so that the damaged areas can be replaced with new parts. You may hear your doctor talk about these techniques. The most commonly used Zimmer minimally invasive and “mini-incision” total knee replacement techniques are called:

MIS Quad-Sparing™ Total Knee Arthoplasty
MIS Subvastus
MIS Midvastus
MIS Medial Parapatellar

What is it like to have knee replacement surgery?

Before Surgery

Once you and your surgeon decide that total knee replacement is right for you, a surgery date will be scheduled, and you may need to do some preparation. For example, your surgeon might ask you to have a physical examination by an internist or your regular doctor. And because blood transfusions may be needed during surgery, you may want to “bank” one or two units of your own blood, to have on hand. You can draw one unit per week, before your surgery.

During Surgery

On the day of surgery, a small tube (intravenous line) will be inserted into your arm. This tube will be used to administer anesthesia, antibiotics, and other medication. After the anesthesia takes effect, your knee will be scrubbed and sterilized with a special solution.

Surgery will take anywhere from 1 to 3 hours, and it will begin with an incision over the knee that will expose the joint. When the bones are fully visible to the surgeon, precision guides and instruments are used to remove the damaged surfaces of the bones.

The replacement parts are then secured to the bones. It might also be necessary to adjust the ligaments that surround the knee. When the surgeon is satisfied with the fit and function of the joint, the incision will be closed.

A tube may be placed in the incision to drain fluids that naturally develop at the surgical site. A sterile bandage will then be applied, and you will be taken to the recovery room, where you will be closely monitored.

Recovery

You will be sent to the recovery room, and as the anesthesia wears off you will slowly regain consciousness. A nurse will be with you, and may encourage you to cough or breathe deeply to help clear your lungs. You will also be given pain medication. When you are fully conscious, you will be taken back to your hospital room.

What Can I Expect After Surgery?

Rehab begins quickly! On the day after your surgery, you’ll get a visit from your physical therapist and begin learning how to use your new knee. You may be fitted with a “continuous passive motion” machine that will gently straighten and bend your knee. Other exercises that promote blood flow to your legs include ankle pumps and pedaling your feet.

Getting up and around soon is important. If you had considerable pain before surgery, you probably cut back on your activities, so your leg muscles may be weak. You will need to build up enough strength to control your new knee, and early activity encourages healing, too. Your doctor and physical therapist will give you specific instructions on wound care, pain control, diet, and exercise.

At home, you will need to continue your exercises, and your physical therapist may continue to work with you. Within 6 weeks after surgery, most patients are able to walk with a cane; and in 6 to 8 weeks, you will probably feel well enough to drive a car.

Even after you have fully recovered from your surgery, you will still have some restrictions like contact sports or other activities that put excessive strain on your knees. Remember, although your artificial knee can be replaced, a second replacement is seldom as effective as the first. But the good news is—in most cases—successful total knee replacement will relieve your pain and stiffness, and allow you to resume most of your normal daily activities. And that really is a happy ending.

* Information provided by Zimmer Biomet Creative Lab