Weight Gain Follows Knee Replacement

Hold the mashed potatoes! Being overweight increases the risk of needing a knee replacement. But, according to Kerry Grens, writing for Reuters Health, a new study finds that knee replacement surgery may also raise a person’s risk of gaining weight. Researchers who analyzed the medical records of nearly 1, 000 knee replacement patients found that 30% of them gained 5% or more of their body weight in the five years following surgery.

One explanation is that people with knee pain have stopped exercising and do not change their habits when they get a new knee and their pain is reduced. “After knee replacement we get them stronger and moving better, but they don’t seem to take advantage of the functional gains” and become more active, said Joseph Zeni, a physical therapy professor at the University of Delaware.

The lead author of the study is Daniel Riddle, a professor at Virginia Commonwealth University, whose group used a patient registry from the Mayo Clinic in Rochester, Minnesota, to examine information on 917 knee replacement patients before and after they had their procedures. The researchers found that five years after surgery, 30% of the patients had gained at least 5% of their weight at the time of the surgery.

Fewer than 20% of those in a comparison group of similar people, matched for age and gender but who had not had surgery, gained equivalent amounts of weight in the same period. “There’s something going on in these patients that predispose them above and beyond their peers to weight gain, ” Riddle said.

The team also discovered that patients who had lost weight before their surgery were slightly more likely to gain weight afterward. Riddle said that could be because when people lose weight in anticipation of an event, such as knee surgery, they are more likely to put on weight after they’ve achieved that goal.

Zeni said that to help people stave off the pounds after surgery, health care providers need to address the sedentary lifestyle people often adopt to accommodate their arthritis. “We need to encourage patients to take advantage of their ability to function better and get them to take on a more active lifestyle, ” he told the Reuters writer.