Billy Sims
Billy Sims was another Lions player who retired at the height of his career. In his first four seasons, he earned three Pro Bowl selections but a terrible knee injury cut his career short and led to his subsequent retirement in 1986.
Terrell Davis
Terrell Davis brought the Broncos to consecutive Super Bowl wins in 1998 and 1999, and won the Super Bowl MVP Honors with the Packers. After being named the NFL MVP in 1998, he suffered a severe knee injury that led him to be on the sidelines for his final two seasons, and ultimately to his retirement.