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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,” said Andrew Urquhart, M.D., a professor of orthopedic 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 mentioned a few options.

“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 said.

What surgery involves

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) as well.

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 said. “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:

Q: What’s causing my knee cartilage to break down?

A: 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; and obesity.

Q: Am I a candidate for total knee replacement?

A: Patients in their 50s 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.

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.

When all of the non-operative options listed above do not work, patients should consult with an orthopedic surgeon. During that consultation, a physician will likely give strength and ligament tests, take X-rays, and discuss symptoms as well as the benefits and risks of surgery.

Q: What’s the difference between partial knee replacement and total knee replacement? I’ve also heard of resurfacing the knee; what does that mean?

A: 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 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.

Q: How long does it take to recover after surgery?

A: 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 by that point, but they may still experience some pain or stiffness.

Q: Will I be able to get back to a physical, active lifestyle?

A: Most patients — about 80 to 85% — feel their knee functions better after surgery than before. 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.