Researchers at the Massachusetts Institute of Technology designed a low-cost prosthetic knee that mimics normal walking motion. The MIT team's prototype generates a torque profile similar to that of able-bodied knees, using only simple mechanical elements like springs and dampers. The team is testing the prosthetic knee in India, an area with approximately 230,000 above-knee amputees.

The engineers analyzed a full set of walking data, including gait, joint angle, the weight of each leg segment, and the ground reaction force during a single step.

The measurements were used to calculate a torque profile — the amount of torque generated by the knee during normal walking. As prostheses are generally one-third to one-half as heavy as human legs and feet, the researchers adjusted the torque profile to apply to lighter leg segments.

Currently, the prototype's spring and two dampers act as brake pads. The spring allows the knee to bend just before the foot pushes off the ground. Simultaneously, the first damper engages to prevent the leg from swinging back. The second damper engages as the leg swings forward, in order to slow it down just before the heel strikes the ground.