In some sense, all athletes use prosthetics. Humans aren't born with spikes, and definitely not with asymmetrical ones optimized for making left turns (especially important in the 200m, where one accelerates throughout the curve of the track)

Amputees can take this to a new level. They can optimize the length of their legs on the distance to run and their fitness. For now, we see that as something that enables people, but I think this guy would not have been allowed to take part in a 'regular' event if he had a real chance to win (the wheelchair marathon is a separate event from the regular marathon for the same reason)