The Dolphins also signed cornerback Evan Oglesby and defensive end Ikaika Alma-Francis. Defensive tackle Jason Ferguson was placed on injured reserve with a season-ending leg injury, and safety Nate Ness was released.
Roth missed training camp and the season's first five games with a groin injury, then compiled four tackles in Miami's last four games. Still, Sparano said Roth was "really impressive" during a 25-23 victory over the Tampa Bay Buccaneers on Nov. 15.
Roth had his best season last year, moving from end to linebacker. He since lost his starting role to Jason Taylor.
Copyright 2009 by The Associated Press