Life After Knee Replacement

Mar 4, 2013

Each year, half a million people in this country have knee replacement surgery, and by 2030 that number is expected to reach three million. After surgery, you might expect those patients to be more active and to lose weight, but a study by Virginia Commonwealth University suggests the opposite is true – and that could spell trouble for the nation’s long-term health. 

People who undergo knee replacement surgery are often overweight.  After all, arthritis in their knees made it painful to move, so exercise was a misery.  Once they had new, bionic knees, many doctors figured those patients would be more active and lose weight, but Dan Riddle, a professor of physical therapy and orthopedic surgery at Virginia Commonwealth University says that’s not the case.

“We didn’t investigate the why.  We just found the what, and the what is that patients who have knee replacement surgery are at substantial increased risk of what we define as clinically important weight gain, which is a weight gain of 5% or more of a person’s body weight," says Riddle.

Working with colleagues at the Mayo Clinic, Riddle studied the records of about 900 patients and found they were 70% more likely to gain weight than a similar population of people who didn’t have surgery.

“These patients, first of all, have arthritis, and it’s severe arthritis, which obviously has been treated surgically, but that doesn’t mean that they don’t have arthritis in other joints.”  

The extra weight means they’re at greater risk for heart disease, diabetes and the need for another knee replacement surgery.  The findings are published in the journal Arthritis Care and Research.  Riddle is also recruiting patients for a new study which could help patients with pain after joint replacement.

“There’s about 20-30% of individuals who get knee replacement surgery who have very difficult time coping with pain. They tend to ruminate about their pain.  They tend to feel helpless.  They can think about almost nothing other than their pain, and this of course has fairly devastating consequences in terms of mobility and functioning and social life," said Riddle.

The idea is to give these patients coping skills.  That could make them feel more comfortable – less likely to obsess and become inactive – a behavior doctors call catastrophizing.

“ We’ve got psychologists involved in our study, and they’re training physical therapists to deliver a pain coping skills training intervention.”

In addition to recruiting patients at VCU, the study – funded by the National Institutes of Health – will enroll patients at Duke, Wake Forest and Southern Illinois University.