Matthews was taken from ANZ Stadium on a medi-cab after being caught in an awkward tackle seven minutes from half-time.
It's a cruel blow for Matthews who was coming off his best season since making his NRL debut in 2008.
The injury is the latest setback for the Dragons who are also dealing with a casualty ward that includes Drew Hutchison (knee) and Yaw Kiti Glymin (shoulder) who are both expected to be out long term.
"He's got a dislocated hip, unfortunately. It's something that's come out of the game that's terrible," McGregor said after the game.