Bush, one of Oakland's two fourth-round selections, was considered one of the top running backs in the country before breaking his leg in Louisville's opener against Kentucky last September. He was coming off a junior season in which he ran for 1,143 yards and an NCAA-leading 23 touchdowns.
Bush did not take part in any team drills during offseason workouts with the Raiders after having a new rod inserted into his leg after the bone didn't heal quickly enough from the initial surgery.
The Raiders are hoping Bush will be healthy enough to compete with LaMont Jordan, Dominic Rhodes and Justin Fargas for playing time when training camp starts Friday. Jordan and Fargas got the bulk of Oakland's carries last season and Rhodes was one of the team's key offseason additions.
But Rhodes will miss the first four regular-season games after being suspended for violating the league's substance abuse policy.
The Raiders also cut safeties Jarrod Cooper and Darnell Bing. Cooper was suspended last week for the first four regular-season games for violating the NFL's policy on steroids.
Bing, a fourth-round pick in 2006, missed all of last season with a neck injury. He was moved from linebacker back to his college position of safety during offseason workouts but was still cut loose.
The Raiders have signed six of their 11 draft picks. Oakland previously signed third-round offensive lineman Marion Henderson, fourth-round cornerback John Bowie, fifth-round defensive end Jay Richardson, fifth-round safety Eric Frampton, sixth-round fullback Oren O'Neal and seventh-round receiver Johnathan Holland.
Four players remain unsigned, including No. 1 overall selection quarterback JaMarcus Russell.