The second-team All-Mountain West Conference selection injured his shoulder last week during a spring practice. While he finished that workout session, he has not practiced since. The junior-to-be found out Thursday that he'll need surgery.
"We're getting ready to lose maybe one of our best players for maybe the early part of the season," Patterson said. "He'll have surgery tomorrow morning."
Patterson said the severity of the injury won't fully be known until doctors get a look inside Carder's shoulder. Patterson declined to elaborate for fear of giving season-opening opponent Oregon State a target, should Carder return.
"If I tell you what the nature of the injury is," Patterson said, "then they go after him."
If Carder misses the Sept. 4 opener against the Beavers at Cowboys Stadium, TCU will start two new linebackers in Patterson's 4-2-5 scheme that employs two linebackers. Daryl Washington, who led TCU in tackles last season, is projected as an early round NFL draft pick.
Carder finished second in tackles last season with 89, 19 more stops than the next-closest Horned Frog. Sophomore-to-be Tanner Brock is projected to start alongside Carder. Linebacker Kris Gardner, who will be a junior, is also out of spring workouts with a shoulder/arm injury.
TCU is coming off a breakthrough season, going 12-0 before losing to Boise State in the Fiesta Bowl, the Horned Frogs' first appearance in a BCS bowl game. TCU finished No. 6 in both major polls.
The Horned Frogs will hold their spring game on Saturday and follow it up with three more practices before wrapping things up until fall camp in August.
Jeff Caplan covers colleges for ESPN Dallas. You can follow him on Twitter or leave a question for his weekly mailbag.