Medical historian Thomas Schlich wrote a fascinating essay for CNN about the history of prosthetic body parts and the "Bionic Men of World War I." From his article:
In all nations involved in the war an emerging generation of so-called "war cripples," as they were referred to in Germany, loomed ominously over the pension and welfare system, and many government bureaucrats, military leaders and civilians worried about their long-term fate.
One solution was returning mutilated soldiers to the workforce. Various prostheses were designed to make that possible, pushing prosthesis manufacturing in many countries from a cottage industry towards modern mass production.
In the United States the Artificial Limb Laboratory was established in 1917 at the Walter Reed General Hospital, in conjunction with the Army Medical School, with the goal to give every amputee soldier a "modern limb," enabling them to pass as able-bodied citizens in the workplace. While the United States remained the largest producer of artificial limbs worldwide, Germany's prosthetic developments incorporated a particular quest for efficiency.
German orthopedists, engineers and scientists invented more than 300 new kinds of arms and legs and other prosthetic devices to help. Artificial legs made of wood or metal, sometimes relatively rudimentary, and often recreating the knee-joint in some way, enabled leg-amputees to stand and move around unaided.