Most Patients Gain Weight

Photo: X-ray of a knee

Old habits pose a risk to people
who received a new knee,
researchers found; © SXC

Researchers found that patients typically drop weight in the first few weeks after total knee arthroplasty (TKA), but then the number on the scale starts creeping upward, with an average weight gain of 14 pounds in two years.

The research involved 106 individuals with end-stage osteoarthritis who had knee replacement surgery, and an age-matched, healthy control group of 31 subjects who did not have surgery. Height, weight, quadriceps strength, and self-perceived functional ability were measured during an initial visit to the clinic, and at a follow-up visit two years later.

“We saw a significant increase in body mass index (BMI) over two years for the surgical group, but not the control group,” says Joseph Zeni of the University of Delaware. “Sixty-six percent of the people in the surgical group gained weight over the two years - the average weight gain was 14 pounds.”

Those who had the knee replacement surgery started out heavier and ended heavier than the control group. The weaker the surgery patients were, as measured by the strength of the quadriceps, the more weight they gained, Zeni notes.

Gaining weight after one knee replacement is worrisome because it could jeopardize the patient's other knee. The researchers note that weight gain after a knee replacement needs to be treated as a separate concern and integrated into post-operative care through a combination of approaches, including nutritional counselling to help patients with portion control, and more emphasis on retraining patients with new knees to walk normally.

“For physical therapists and surgeons, the common thinking is that after a patient's knee has been replaced, that patient will be more active,” says researcher Lynn Snyder-Mackler. “But the practices and habits these patients developed to get around in the years prior to surgery are hard to break, and often they do not take advantage of the functional gain once they get a new knee,” she notes.

“We need to re-train patients with new knees to walk more normally and more systematically. And we need to encourage community participation,” Snyder-Mackler adds. “We need people with new knees to get out there - with the help of their family, their friends, and the community at large.”; Source: University of Delaware