After watching replays, the league determined not to fine Ward, who was also not penalized by officials for the hit. Rivers was placed on injured reserve Tuesday, a day after having season-ending surgery to set his jaw.
Rivers was injured when Ward hit him from the side during Pittsburgh's 38-10 victory on Sunday. The first-round draft pick was second on the team in tackles and had one interception.
"I'm not doing anything illegal. It was a clean hit," Ward said after the game. "I didn't stand over the guy or anything ... I'm not going to change my ways. If they're going to keep fining me for that, then I'm going to get fined all year."
Ward was fined a total of $15,000 for two infractions by the league last week, although the Steelers publicly disagreed with the decision.
It's the second time in the past three years that a first-round Bengals draft pick has suffered a season-ending injury. Linebacker David Pollack, chosen in 2005, cracked a bone in his neck during his second season, ending his career.
Also Tuesday, the Bengals waived kicker Dave Rayner, who played the past two games while Shayne Graham recovered from a strained groin, and signed guard Andrew Crummey from Washington's practice squad.
Rayner kicked a 26-yard field goal against the Steelers, his only attempt in his two games, and made three extra points. Graham is expected to be ready to play in Houston on Sunday.
Crummey was signed by the Redskins as an undrafted free agent from Maryland. He played in all four preseason games before joining the practice squad.
Information from ESPN.com's James Walker and The Associated Press was used in this report.