On October 7, 1975, Ysidore M. Martinez received U.S. Patent No, 3,909,854 on a Knee Implant Prosthesis:

Ysidore, an amputee, revolutionized the prosthetic field by creating a prosthesis that was better at giving the wearer control of acceleration and deceleration, while simultaneously reducing pressure and friction for the wearer. This concept, a departure from trying to make prosthetics that faithfully mimicked the limb being replaced, is still used in prosthesis’ today.