TUESDAY, March 18, 2014 (HealthDay News) -- Losing or gaining weight after joint-replacement surgery affects the ultimate success of the operation, according to a new study.
Patients who lost weight after knee-replacement surgery had much better results in terms of pain, function and activity levels than those who maintained or gained weight, the researchers found.
But in both knee- and hip-replacement patients, weight gain was associated with poorer outcomes, according to the study, which was presented at this month's annual meeting of the American Academy of Orthopaedic Surgeons in New Orleans.
"Based on our findings, as physicians, we should convey to our patients the importance of maintaining good health and an appropriate weight, and we should help them in any way we can to achieve this goal," said Dr. Geoffrey Westrich, senior investigator and director of research in adult reconstruction and joint replacement at the Hospital for Special Surgery in New York City.
Researchers looked at body-mass index (BMI) changes in the two years after nearly 7,000 patients received hip or knee replacements. BMI is a measure of body fat based on height and weight.
No change in BMI was seen in 84 percent of hip patients and 74 percent of knee patients. People who were obese before joint-replacement surgery were more likely to lose weight than those who were overweight or normal weight.
The researchers also found that overweight or obese women were more likely to lose weight than normal-weight women or men. And people who were more active before their joint replacement were more likely to maintain their weight than to lose or gain weight.
"Our findings represent the first report to present evidence that weight loss is associated with improved clinical outcomes, while weight gain is associated with inferior outcomes, although these results are really not surprising," Westrich said in a hospital news release.
Each year in the United States, there are about 719,000 knee replacements and 332,000 hip replacements, according to the U.S. Centers for Disease Control and Prevention.
Data and conclusions presented at meetings typically are considered preliminary until published in a peer-reviewed medical journal.
The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has more about joint replacement.