<p>
Houston Texans star linebacker Brian Cushing will start training camp on the physically unable to perform list.</p> <p>
Cushing is coming off a knee injury. He's expected to be ready before the start of the season.</p> <p>
Rookie nose tackle Louis Nix and outside linebacker Trevardo Williams are on the physically unable to perform list.</p> <p>
Meanwhile, the Texans cut offensive tackle Brennan Williams with a failed physical designation.</p> <p>
Follow me on Twitter: <a href="http://www.twitter.com/RavensInsider">@RavensInsider</a></p> <p>
Aaron Wilson covers the Ravens for The Baltimore Sun</p>