Weight and Age Drive Knee Replacements

What factors are driving the joint replacement business? The annual market for knee implants is roughly $4 billion in the U.S., according to Bloomberg analyst Jason McGorman. John Tozzi, a Bloomberg writer, notes that Americans are getting older and heavier—which means trouble for the knees of the country.

Tozzi writes that the rate of total knee replacements doubled from 2000 to 2010 for Americans over age 45. At the same time the average age of patients increased by more than two years to 66.2. Surgeons performed about 700, 000 knee replacement surgeries in 2010 making it the most common patient hospital procedure for people over age 45.

Tozzi points out the two big demographic shifts that help explain the knee replacement boom. One is that people are living longer: He claims that life expectancy for 65-year-olds increased by a year-and-a-half from 2000 to 2010.

The fact that more and more Americans are overweight and obese compounds the problem. David Ayers, M.D., chairman of orthopedics and physical rehabilitation at the University of Massachusetts Medical School has analyzed data on 35, 000 joint surgery patients. He said that people who have joint replacements before age 60 are more likely to be obese and to have other health problems. “It’s not that these are young, healthy, fit people, ” said Ayers.

Tozzi quotes David Teuscher, M.D., president of the American Academy of Orthopaedic Surgeons, who notes that the force on the knee when going up stairs can be three to five times body weight. “Not everyone who suffers from obesity gets knee pain, but the extra weight can aggravate arthritic knees, ” he said.