When is it time for a knee replacement?

Knee replacement surgery is one of the most common procedures in the United States, with more than 790,000 performed each year.

Deciding the time for knee replacement needs to be determined by you and your doctor, but certain factors make it more likely, according to experts at Keck Medicine of the University of Southern California.

• Bad arthritis. "Osteoarthritis, rheumatoid arthritis and post-traumatic arthritis affect the knee through different mechanisms, however, these different conditions are similar in that they all result in loss of cartilage, which causes pain and loss of motion," Dr. Nathanael Heckmann, orthopedic surgeon at Keck Medicine, said in a Keck news release. "When these symptoms become severe, knee replacement surgery may provide considerable symptom relief by replacing the worn-out surfaces of the knee."
• When nonsurgical treatments such as medications, steroid injections and physical therapy are no longer effective. "As time passes, these arthritic conditions tend to progress in severity, rendering these types of treatments less and less effective," Heckmann said.
• Your knee pain prevents you from doing normal activities or caring for yourself. "In general, the timing of a total knee replacement is determined by the impact the knee is having on your quality of life," said Dr. Jay Lieberman, chief of orthopedic surgery at Keck Medicine. "If conservative treatments are not working and you have significant pain while walking, you may be a good candidate for surgery."
• Severe knee pain. Especially if it happens even when resting and you can't sleep.
• Swollen knees. Particularly if your knee is always swollen.
• Your knee has become deformed. If you have advanced arthritis, it can affect the way you walk, which can also lead to further problems elsewhere in your body.
• You're of a certain age. While knee replacements are done in people of all ages, they're most common in those older than 60. That's because younger people's more active lifestyles may place too much strain on the artificial knee and shorten how long it lasts, and second replacement surgeries may not be as successful.

If you're thinking about knee replacement surgery, you need to know that you may have to avoid high-impact activities.

"Total knee replacement is quite successful in enabling patients to return to an active lifestyle—patients can perform all types of recreational activities, including hiking, bicycling, skiing, surfing, tennis and golf," Lieberman said in the release. "In general, we do not limit activities but suggest that patients avoid impact activities on a consistent basis to reduce wear on the prosthesis."