DEAR MAYO CLINIC: I was diagnosed with knee osteoarthritis. When is a knee replacement appropriate?

ANSWER: Osteoarthritis is an extremely common condition affecting over 500 million people worldwide. The knee is the most frequently affected joint. Knee osteoarthritis occurs when protective cartilage in the knee wears down leading to inflammation and pain. Commonly, patients will have bone spurs, and the normal shape of their knee is disrupted.

Symptoms of knee osteoarthritis may develop slowly, or in some patients it may come on relatively quickly. The most common symptoms include pain with weight-bearing activities, stiffness and decreased function.

Knee osteoarthritis has several causes, but the most common causes are genetic predisposition and activity level. Other risk factors include age, gender, obesity, prior surgery or prior trauma to the knee.

The diagnosis of knee osteoarthritis is made based on a combination of a thorough medical history, a detailed physical examination and imaging, which is most commonly performed with X-rays.

When diagnosed with knee osteoarthritis, several treatment options are available. In general, nonoperative treatment is recommended first. The most common nonoperative treatments are oral pain medications, activity modification, use of gait aids while walking, or injections.

For pain medications, we typically recommend non-opioid medications such as acetaminophen, or not steroidal anti-inflammatories such as ibuprofen or naproxen. The goal of these medications is to reduce the inflammation and subsequent pain associated with osteoarthritis.

Similarly, activity modification and the use of a gait aid are aimed at reducing the load in the knee that, subsequently, can cause pain.

The most common injection for the knee is a steroid. The goal is to reduce joint inflammation and improve symptoms. Some patients may get relief from these nonoperative treatments for months while others only get a good response for a few weeks.

Knee replacement is indicated when patients have tried several nonoperative treatments and they are no longer working. Knee replacement is most appropriate when the pain limits activities and quality of life. This may mean patients are no longer are doing activities that they love such as walking or exercising.

Many patients can live with their knee osteoarthritis without having surgery, as the nonoperative treatments are effective for them. Knee replacement is reserved for those who have both activity limitations and have failed nonoperative treatment.

During a knee replacement, the surgeon cuts away the damaged bone and cartilage from your thigh bone (femur), shin bone (tibia), and in some cases the kneecap (patella). These areas are then replaced with an artificial joint typically consisting of metal and high-grade medical plastic.

For a majority of patients, a knee replacement significantly improves pain and function and increases mobility. In some cases, however, complications do occur. This is why we recommend surgery only for patients who understand the risks and benefits of the procedure and are willing to undergo a surgery while understanding those risks to relieve their pain.

To help make the decision of whether a knee replacement is appropriate, a patient should see an orthopedic surgeon who can perform that careful history, physical examination and review the X-rays with the patient. The surgeon can then review the risks and benefits of the procedure and discuss through a shared decision-making process if surgery would be appropriate for the patient.

Although nonoperative treatments are effective for the majority of patients with knee osteoarthritis, they do not work for everyone. If you are interested in learning more about knee replacement, seek a full evaluation and consultation from an orthopedic surgeon who can review your condition and discuss what options might work best in your individual situation. — Charles Hannon, M.D., M.B.A., Orthopedic Surgery, Mayo Clinic, Rochester.

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