Garrard was slated to start Friday night's game against Tampa Bay, but instead was getting ready for surgery on his left knee.
The issue apparently deals with wear and tear. Garrard looked fine at practice Wednesday night, the last time the Dolphins practiced in front of the media.
Garrard missed all of last season after being released by Jacksonville and then undergoing back surgery.
With Garrard sidelined, Matt Moore started against Tampa Bay and now appears the leader for the starting job for the Houston opener on Sept. 9 unless first-round pick Ryan Tannehill develops quickly and convinces the coaching staff he's ready to start right away.