When cartilage inside the knee joint starts to break down, a person may begin to experience pain.

"If you were to look inside a healthy knee joint you'd see a thick cushioning of cartilage that covers and protects the ends of your bones, as well as another type of cartilage, called the meniscus, that acts like a shock absorber between the bones," says Andrew Urquhart, M.D., a professor of orthopaedic surgery at Michigan Medicine's Comprehensive Musculoskeletal Center.

"The meniscus keeps the knee joint stable and helps evenly spread out the weight the knee joint bears, but when a person's knee cartilage is deteriorating, the bones rub together and they may experience pain when walking or weight bearing."

To treat a painful knee, Urquhart mentions there are a few options.

"I think many patients jump to surgical options, but we recommend every patient start with diet and exercise or physical therapy before considering knee replacement surgery," he says.

Total knee replacement surgery involves capping off the thigh bone (femur) and shin bone (tibia) with metal and inserting a plastic bearing, or artificial joint, in between the bones where cartilage would normally exist. In some patients, a plastic cap is inserted over the kneecap (patella).

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Urquhart notes that the surgery shouldn't be taken lightly.

"About 15 to 20% of patients that undergo knee replacement surgery have buyer's remorse because they still experience discomfort or a sensation of instability in their knee, even after surgery," Urquhart says. "That's why we strongly encourage patients to try non-surgical options before electing surgery."

Urquhart answers some common questions he hears from patients about knee replacement surgery:

What's causing my knee cartilage to break down?

Urquhart: There are a number of conditions that can cause knee pain and the cartilage to deteriorate. Some of the most common are arthritis, an injury, such as tearing the meniscus, inflammatory arthritis and obesity, among others.

Am I a candidate for total knee replacement?

Urquhart: I always start by telling patients that total knee replacement surgery shouldn't 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 person's 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.

I've lost weight and did physical therapy, but I'm still in pain. What's next?

Urquhart: When all of the non-operative options listed above do not work, patients should consult with an orthopaedic surgeon to discuss partial or total knee replacement surgery.

The consult will usually include discussing symptoms, a few strength and ligament tests, X-rays and discussing the benefits and risks of surgery. 

What's the difference between partial knee replacement and total knee replacement? I've 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 knee's cartilage. Patients usually hear about resurfacing for hips, which is a type of total hip replacement surgery. At Michigan Medicine, we don't 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. 

Are there different surgical techniques for total knee replacement?

Urquhart: Yes. There are a variety of surgical techniques that can be used including robotic-assisted surgery, computer-navigated surgery and custom cutting blocks. There is no scientific evidence that proves one technique works better than the other or results in better outcomes for patients.

How long will total knee replacement surgery take?

Urquhart: I like to put it in perspective for patients by using a flight analogy. While the actual operation may only take an hour or so, similar to a one-hour flight from Detroit to St. Louis, you should still budget plenty of time for the multiple steps before and after surgery — just like the added time you budget to spend at the airport for security, checking your bags, etc.

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Do you have to come to the hospital for total knee replacement surgery?

Urquhart: Knee replacements in healthy patients do not require a hospital stay. In fact, we now offer the surgery at the Brighton Center for Specialty Care, one of our outpatient specialty clinics.

Patients have the surgery performed in one of the operating rooms at the facility and then are moved into a recovery area where they are monitored and work with physical therapy to be safe to go home. The center has the ability and staffing to monitor patients overnight, if needed. Then the patient is able to finish their recovery at home.

What are possible side effects of the surgery?

Urquhart: All surgeries have a risk of complications. Less than 1% of healthy patients undergoing any type of surgery can experience a cardiovascular event, such as a heart attack or stroke. About 0.5% of knee replacement surgery patients develop an infection.

But an important side effect or outcome to talk about is this buyer's remorse idea I brought up earlier. About 15 to 20% of patients that undergo total knee replacement surgery have buyer's remorse because they still experience discomfort, clicking or a sensation of instability in their knee, making them regret having the procedure. That is exactly why we consider non-surgical options first and remind patients that they should not make the decision to have surgery without careful consideration.

How long does it take to recover after surgery?

Urquhart: Every patient's recovery time is different, but most patients can expect to be up and walking without a cane or walker about four weeks after surgery. They can generally bend their knee to or beyond 90 degrees at this point, but may still experience some pain or stiffness.

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.