NBA player Jason Kidd withdrew from the 2004 Olympics because he needed knee surgery. More specifically, he underwent microfracture surgery on his left knee in July 2004 to repair damaged articular cartilage. The injury had troubled him during the 2003–04 NBA season and required a recovery period that ruled him out of the Athens Games.
Microfracture surgery repairs cartilage by creating tiny holes in the underlying bone, allowing marrow cells to form new repair tissue. In 2004, it was a significant procedure for athletes with cartilage damage, although outcomes varied widely depending on the injury and rehabilitation.
Kidd had already won Olympic gold with the United States in Sydney in 2000. His absence was notable because he was an experienced point guard and one of the NBA's best floor leaders. He later returned to Olympic competition at Beijing in 2008, where he helped the U.S. win gold with the team later nicknamed the “Redeem Team.”