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If your knee hurts when you walk or get up from a chair, or it keeps you from doing daily activities, you might wonder: Is knee replacement surgery in your future?

More than 700,000 complete knee replacements are performed in the U.S. every year. About 90% of people who have the surgery get major pain relief and are able to get back to their everyday life.

Does that mean surgery is for everyone with knee problems?

"Knee replacement surgery is not like getting a tire change at a NASCAR pit stop," says orthopedic surgeon David Lewallen, MD, at the Mayo Clinic College of Medicine in Rochester. "It's a major procedure and isn’t something that has to be done unless your symptoms can't be controlled with simpler measures."

When to Consider a Knee Replacement

If you are considering a new knee, here are things to think about:

  • Pain, swelling, and stiffness. If your knee hurts when you walk or go up and down stairs, and it hurts to get through your day, that's a sign you might need help. Your knee may hurt at night or even when you're resting. You should think about having the surgery if your pain hasn’t been under control for a while and you’ve tried nonsurgical treatments.
  • Other treatments didn't work. Surgery isn't a first step. "We always try to start with simpler things first and move to more complicated solutions," says Lewallen. That means you've probably already tried anti-inflammatory medication or cortisone shots for pain and swelling, physical therapy, and maybe even weight loss.
  • Knee deformity. "Do you notice you're becoming bowlegged or knock-kneed or your knee won't go straight anymore?" says orthopedic surgeon Claudette Lajam, MD, of the NYU Langone Medical Center in New York City. "It's usually a giveaway when that starts to happen."
  • Quality of life. If your pain limits what you can do every day, you may want to talk to a surgeon. "It's about timing," says Charles Nelson, MD, chief of joint replacement at Penn Orthopaedics in Philadelphia. "People think surgery when symptoms are bad enough that they're not functioning to their satisfaction."

When You Should Think Twice

A knee replacement may not be the best choice in some cases:

  • Infections. If you’ve had a recent infection, you’ll need to get it treated before surgery. For example, don’t postpone dental care for gum and teeth infections. Taking care of this will lower the chance of infection in your new joint, which is a serious problem that can lead to more surgery.
  • Other health issues. A history of heart or lung problems, diabetes, or blood clots may make you more likely to have trouble with the surgery. Your doctor will want to get these health issues under control before deciding to operate. He may also suggest you lose weight or quit smoking.
  • Unclear cause of knee pain. "Is your knee really causing your pain?" says Lajam. "Sometimes you get pain from the low back that causes your knee pain. Sometimes people with bad hip arthritis have pain in the knee." Work with your doctor to make sure you've found the real source of your pain. If you don't, your knee may still hurt just as much months after surgery.