The American Academy of Orthopaedic Surgeons projects that by 2030, 3.48 million total knee replacements and 572,000 total hip replacements will be performed annually in the United States. In 2004, the last year for which the academy has released data, U.S. hospitals performed 478,000 total knee replacements and 234,000 total hip replacements.
The demand is driven by baby boomers who want to maintain active lifestyles. Advances in materials that make for longer-lasting implants mean more people are getting new joints at younger ages.
Older implants had a life expectancy of 10 to 15 years; newer ones are expected to last years longer.
In the 1970s, when doctors first started performing joint replacements, they generally wouldn’t perform them on patients younger than 60, said Dr. Douglas Dennis, an orthopedic surgeon in Denver and spokesman for the national association.
Nowadays, because materials are more advanced, patients in the 40s and 50s are getting new hips and knees.
Widner adds a third reason the numbers are growing: the increasing prevalence of obesity, which puts more stress on joints.