ON MARCH 14, 2000, National Basketball Association star Sean Elliott took to the floor of the Alamodome, the home court of his team, the San Antonio Spurs, and played basketball. As he headed for a dunk, Elliott slipped and fell to the floor. He quickly got up. Later in the quarter, he drove to the basket again, only to be stopped by opponent Dikembe Mutombo of the Atlanta Hawks, who sent Elliott down again, this time on his back. The hometown crowd was not amused.

Basketball is a physical sport, with its share of pratfalls and elbow jabs. Elliott's falls were not unusual, and Mutombo hadn't been playing unfairly. Spurs fans were aware, however, that the game marked Sean Elliott's first time on the court since receiving an organ transplant seven months earlier. The starting forward had been suffering from advanced kidney disease. Sean Elliott's older...