Obesity Driving Knee Replacements Over Hips

More knees are being replaced in the U.S. than are hips and Peter B. Derman, M.D., MBA, an orthopedic surgery resident at the Hospital for Special Surgery in New York, wondered why. So he conducted a study and found that the increase in the number of overweight and obese people in the United States accounted for 95% of the higher demand for knee replacements.

Derman and his colleagues reviewed ten years of data on knee and hip replacements including the patients’ length of hospital stay, hospital mortality and workforce trends.

According to Jaleesa Baulkman, writing for University Herald, they found that patients ages 18 to 64 experienced a more rapid rise in overweight and obesity, when compared to patients older than age 65. From 1997 to 2009, the share of patients ages 18 to 64 undergoing knee replacement rose 56%, compared with only 35% for hip replacement.

“We found that this differential growth rate in total knee replacement procedures could not be attributed to changes in physician or hospital payments, length of hospital stays, in-hospital death rates, or surgical work force characteristics, ” Derman said. “Because excess body weight appears to be more damaging to the knee than to the hip, the increasing prevalence of overweight and obesity may explain the growing demand for knee replacements over hip replacements.” Derman published his findings in the Journal of Bone and Joint Surgery.