The New Orleans Saints placed three players on the physically unable to perform list, according to Ian Rapoport of NFL Network.
Harper's injury was not disclosed by the Saints, but he is joined on the PUP list to start camp by linebacker Victor Butler, who is coming off an ACL injury and cornerback Patrick Robinson, who also suffered a knee injury in mini-camp.
Harper is scheduled to start alongside first-round pick Kenny Vaccaro for the Saints at safety.
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Terry McCormick covers the Titans for TitanInsider.com