PORT JEFFERSON - For the first time in the United States, a robot assisted in a total knee replacement surgery on Long Island.

Mather Hospital has been using robot-assisted equipment for about a year, but now it has started using it for total knee replacements.

Laurie Mullens, 63, says she suffered for more than a decade with arthritis in her knees.  

"Before my surgery, I wasn't even really able to walk and I had a bad limp," says Mullens.

The Farmingdale woman decided it was time to do something. She had her left knee replaced in March. It went so well that she agreed to have doctors do her right one, with the aid of a robot.

The technology involves sensors, cameras and a computer to allow the surgeon to map out the patient's knee in 3-D. Then, the doctors decide on a course of action and input that plan into the computer.

"It won't let me go more than one millimeter off of where I want to put it," says Dr. Brian McGinley.

Mullens says she is in physical therapy and on the path toward recovery.

"I'm doing all kinds of exercises. It feels just as good as the other one," says Mullens.

Dr. McGinley says the robot-assisted procedure is appropriate for any patient who needs partial or total knee replacement surgery. Doctors at Mather have several more surgeries already scheduled for the next few weeks.