The Olympic aspirations of Oscar Pistorius, a double-amputee sprinter from South Africa, may end soon. Track and field’s world governing body is expected to announce that he is ineligible to race against able-bodied athletes because his state-of-the-art prosthetics give him an unfair advantage.

Pistorius was born without the fibula in his lower legs and with other defects in his feet. He had both legs amputated below the knee when he was 11 months old but has gone on to set Paralympic world records in the 100, 200, and 400 meters. He has defeated some able-bodied runners in his pursuit of attaining an Olympic qualifying time, touching off international debate over...