Some people have joints that look like they are more than a decade older than they are, says a new UK survey.
The study found overweight as being a major factor and suggested that obese people add at least five years to their joint age, reports the Daily Express.
Yet one in five, 25 to 34-year-olds also have a joint age over 50.
Some under-35s have even older joints than their parents and in some cases their grandparents, according to the study of 13,000 people.
People who took the survey answered questions about their lifestyles, including their weight and how much exercise they do, which were then run through a joint age calculator on a site run by supplements company Seven Seas.
People were also asked to complete exercises, including touching their toes and crossing a leg.
"Joint problems aren't something that you can put off worrying about until you grow old," said Osteopath Torben Hersborg, who helped create the calculator.
And experts believe knee replacements could rise by 700 per cent by 2030.