In results that surprised even orthopedic surgeons, a new study finds that most people return to work after a total knee replacement – even those with physically demanding jobs.

"We were very surprised by the results," said study author and orthopedic surgeon Dr. Adolph Lombardi, president of Joint Implant Surgeons, an orthopedic surgery practice in Columbus, Ohio which specializes in knee and hip replacements. "We're doing an operation that is helping patients to stay in their work environment."

The research, presented at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) in Chicago, shows that 98 percent of people who undergo total knee replacements are able to go back to work afterward – 89 percent to the same type of work they performed prior to the surgery. Approximately 700 patients from 18 to 60 years old who had knee replacements at one of five different health care facilities were questioned for the survey. Their work ranged from sedentary (desk-type work) to highly physical labor.

Ninety-seven percent were able to return to very heavy work, and 98 percent went back to heavy work. Ninety-five percent headed back to sedentary jobs, 91 percent returned to light jobs and 100 percent returned to medium-intensity work. Men were significantly more likely than women to return to work, the study found.

The need for total knee replacement can be caused by arthritis, age, sports injuries or other conditions. More than 650,000 people in the U.S. undergo knee replacement each year.

"These studies show there is a cost savings to society," said Dr. John Tongue, president of the AAOS. "People are getting back to work. They can pay taxes instead of being on disability."