Sit down, stand up, climb stairs&8212;Ossur's Power Knee is the first motorized prosthesis to give leg amputees fluid motion by simulating the movement of the real knee next to it. A series of sensors strapped to the healthy leg measure pressure and motion 1,350 times a second to determine where the leg is going and how fast. The data transmit wirelessly to an artificial-intelligence processor on the 10-pound, battery-operated Power Knee. The microchip controls a brushless motor that drives the device precisely in sync with its healthy neighbor.