Bush played in three games for Denver earlier this season, including the opener when Ward served a one-game suspension, before being cut to make room for offensive tackle Tyler Polumbus.
He spent a week with the Bills after his release from the Broncos.
Ward was hurt in Denver's win over New England on Sunday night on the same play that run-stuffer Sylvester Williams sprained his right ankle.
Both are expected to miss Sunday's game at San Diego and could be sidelined much longer.
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