FDA approves first implant system for adults who have above-the-knee amputations The U.S. Food and Drug Administration today approved the Osseoanchored Prostheses for the Rehabilitation of Amputees (OPRA) Implant System, the first implant system marketed in the U.S. for adults who have transfemoral—or above-the-knee—amputations and who have or are anticipated to have rehabilitation problems with, or cannot use, a conventional socket prosthesis. Today's approval of the OPRA Implant System expands options for prostheses for individuals who have had above-the-knee amputations and can help those who have had or may have problems with rehabilitation and have not been able to benefit from available socket prostheses. Prostheses can help people who have lost a leg due to trauma or cancer to regain mobility and to more easily participate in everyday activities."