Big Step Forward
By Bridget Finn

(Business 2.0) – Ossur's new Rheo Knee is the most sophisticated prosthetic joint on the market today. It adjusts to even minor differences in terrain and is self-learning: The longer a user wears it, the more data its microprocessor absorbs, rendering its action ever more lifelike. -- BRIDGET FINN

With each step, the actuator adjusts the knee's resistance as needed. A current charges the carbyl-iron-based fluid inside the actuator, making it thinner or thicker to provide less or more resistance.

The knee can be programmed via a Hewlett-Packard iPaq loaded with special software. Adjustments to knee swing or stance are downloaded to the Rheo by cable.

The microprocessor acts like a brain, interpreting data retrieved from the sensors and translating it into commands for the actuator.

Sensors in the knee soak up data on the angle and force on the knee from the environment at a rate of 1,000 times per second. The microprocessor can then calculate the walker's speed and the angle of the terrain.