At the precise moment when physical activity finally becomes more possible, people who have recently undergone knee replacement surgery often do just the opposite. They hold back, retaining their past inactive behaviors, and in the process, they gain weight.

These findings recently appeared in Osteoarthritis and Cartilage, the official journal of the Osteoarthritis Research Society International. The results raise strong concerns, as experts say that gaining weight after one knee replacement can easily jeopardize the health and stability of the patient’s other knee… sometimes leading to more surgery.

The study looked at one hundred and six individuals who had undergone knee replacement surgery and compared them to an age-matched, control group of thirty-one people who did not have surgery. Each person was measured for height, weight and quadriceps strength at an initial exam, and then two years later.

In the first few weeks after total knee replacement surgery, researchers found that patients had reported a significant drop in their weight. Shortly thereafter, however, those individuals began to gain weight. Almost sixty-five percent put on an average of fourteen pounds over the two-year study.

The researchers noted that old practices are difficult to overcome. And because patients had restricted mobility in the years prior to surgery, they often don’t take advantage of the functional gain once they got a new knee. To maximize the benefits of the surgery, they recommend doctors treat the weight gain as a separate and unique issue after surgery, and incorporate nutritional counseling and specific therapy to retrain the patients with new knees to walk normally.