What to Expect After Knee Replacement Surgery: Treatments, Recovery

Knee replacement surgery is a last resort. The invasive procedure to install an artificial joint comes only after all efforts to cope with worn out knee cartilage (osteoarthritis) have failed to relieve disabling pain.

There are two main types of knee replacement surgery, and you may be a candidate for one or both.

About the Knee

The knee joint is a complicated piece of machinery that allows you to bend your leg so you can walk, run, squat or jump.

The joint is made up of the thighbone (femur), shin bone (tibia) and kneecap (patella). The knee also includes:

— Cartilage that cushions the ends of the bones and the back of the kneecap, so bones don’t grind against each other.

— Ligaments that tether the bones together and stabilize the knee.

— Muscles that attach at the knee, such as the quadriceps and hamstrings.

— Tendons that tie muscles to bones.

Fluid-filled sacs (bursae) that help reduce friction to knee tissues.

The whole joint is wrapped in a package called a joint capsule, a thin membrane filled with lubricating fluid to keep the knee in good working order.

What Goes Wrong

Over time, knee cartilage can deteriorate. It’s typically due to years of wear and tear, and you may not even notice the process. “Cartilage doesn’t have nerve endings, so the loss of cartilage doesn’t hurt. But that changes when the bones touch,” explains Dr. Seth Jerabek, a hip and knee surgeon at Hospital for Special Surgery in Manhattan.

Since the knees take an enormous amount of pressure and stress as we move about, cartilage loss can lead to disabling pain, stiffness and inflammation.

The first line of defense is strengthening muscles that support the knee, losing weight and getting injections of anti-inflammatory medications (corticosteroids). If those strategies don’t relieve knee pain, a knee replacement can help.

[10 Ways to Prepare for Surgery.]

Total Knee Replacement

A total knee replacement sounds like it involves getting an entirely new joint. It might be a misnomer. “It’s more of a knee resurfacing, like getting a crown for your tooth. Dentists shave down the tooth and put a cap on it. That’s similar to what we do with the femur, tibia and patella. We remove about 9 millimeters of the surface of each bone to fit a cap (implant) on there and give the bone a new, smooth surface,” says Dr. Adam Sassoon, a hip and knee surgeon at UCLA Health.

Artificial knee parts are made of metal and plastic. Installing them requires a surgeon to make an incision about six to 10 inches long, cut out one or more major ligaments, separate the femur and tibia from the knee, and sometimes cut into the quadriceps muscles. “When you cut off the top of the tibia, you have to sacrifice the anterior cruciate ligament in the center of the knee,” Jerabek says. “The implant then makes up for the ACL to stabilize the joint. But really, there’s no way to make it perform like an ACL, so it can be harder after knee replacement to pivot and twist in activities like soccer or basketball.”

Whether you’re a candidate for a total knee replacement depends the amount and location of the of cartilage loss. Doctors talk about location in terms of “compartments,” such as:

— The patellofemoral compartment (the undersurface of the kneecap and portion of the femur the kneecap rubs against).

— The medial compartment (the inner side of the knee between the femur and tibia, closer to your other leg).

— The lateral compartment (the outer side of your knee between the femur and tibia).

The more damage you have, the more likely it is that you’ll need a total knee replacement. “If you have arthritis in all three compartments — or in both the medial and lateral compartments, and both are worn out — you’re going to have a total knee replacement,” Sassoon says.

[See: Questions to Ask an Orthopedic Surgeon.]

Partial Knee Replacement

When the cartilage loss is limited to one part of the knee, you might be a candidate for a partial knee replacement. “The most common (scenario) is arthritis isolated to the inside or medial compartment. Those patients do well with partial knee replacements,” Jerabek says.

Like a total knee replacement, a partial knee replacement involves an incision — this one about four or five inches long — as well as the removal of damaged cartilage and bone, and the installation of replacement parts. “But the parts are smaller and you don’t insert them as deep into the bone,” Jerabek notes.

Because the parts are smaller and limited to one location, doctors don’t have to remove knee ligaments, either. “That’s better for people who are more active,” Sassoon says.

But the procedure isn’t for everyone with knee arthritis limited to one area. You might have to skip a partial replacement if you have:

— Osteoporosis or advanced obesity. “The stresses between the implant and the bone could predispose you to a bone fracture,” Sassoon points out.

— A diagnosis of an inflammatory arthritis condition such as rheumatoid arthritis or lupus. “They’re progressive autoimmune diseases,” Sassoon says,” and “that will eventually cause destruction.”

Even if you’re a great candidate for a partial replacement, it doesn’t mean you’ll avoid further knee problems. “The potential problem with a partial knee replacement is that you can still get arthritis in the other knee compartments that weren’t replaced,” Jerabek says, “so a lot of people jump right to the total replacement.”

High-Tech Surgery

It takes impeccable skill and precision to align an artificial knee joint properly. That’s why computer- and robot-assisted surgeries are becoming common, especially for a partial knee replacement. “Putting a partial knee in is like building a ship in a bottle, because you’re trying not to disrupt the ligaments,” Jerabek says.

Computers and robotic tools help doctors:

— Scan the knee ahead of time and make a 3D plan of where to place the components based on a person’s unique needs.

— Remove the offending bone during surgery with pinpoint precision.

“There’s better accuracy and an improved ability to achieve overall corrective limb alignment when you use robotics and computer navigation,” Sassoon says. “They allow us to make perfect cuts perpendicular to the axis of the bone we’re cutting or dial in a correction we may want to achieve.”

The approach your doctor uses will depend on skill, preference and available tools.

[Read: Exercising After You’ve Gone Under (the Knife, That Is).]

What to Expect

Knee replacement surgeries are typically done on an outpatient basis, with most patients going home the same day. People with underlying medical conditions, such as an irregular heart rhythm or kidney problems, will likely have to be monitored overnight in a hospital for a full knee replacement.

Once at home, you’ll need the right equipment (such as a walker or raised toilet seat) and someone who can help take care of you for a few days or more and assist you with medications, bandage changes and food preparation. You’ll also have to be on the lookout for infection, blood clots and partial knee stiffness, which are all risks of knee replacements.

The most important aspect of recovery is physical therapy, which you do at an outpatient physical therapy center a few times per week. “For a total knee replacement, most people are in formal physical therapy for three months. For partial knees, you bounce back twice as fast, because we’ve removed less bone and kept all of the ligaments,” Jerabek says, “and we didn’t have to dislocate the tibia from underneath the femur.”

Once you’re back to your regular activities, you should be able to get 15 to 20 years of use from a partial knee replacement, and up to 30 years for a full knee replacement.

There will always be a small risk, around 1% per year, that the new parts fail for reasons such as loosening, stiffness, instability or infection. So it’s important to do everything you can to maximize the replacement. For example:

— Keep up with exercises to strengthen the muscles that support the knee joint and maintain motion.

— Avoid putting too much pressure on the knee. “Focus on lower impact exercises like cycling, swimming or using an elliptical machine,” Sassoon says. “You can do more with a partial knee replacement. I don’t think I’d go back to training for a marathon or sports that require a lot of jumping, but things like tennis are OK, as long as you stick to doubles with less court to cover or play on grass or clay.”

And enjoy being active, whatever that looks like for you. “You can get back to doing things for the first time in a while without pain. I call it the ‘second first time.’ Maybe it’s skiing or surfing or just walking through your house or a store,” Sassoon says. “You’ll value the feel of function without pain.”

More from U.S. News

10 Ways to Prepare for Surgery

Types of Orthopedic Surgeries

Exercising After You’ve Gone Under (the Knife, That Is)

What to Expect After Knee Replacement Surgery: Treatments, Recovery originally appeared on usnews.com

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