It's the second straight year Cushing has been lost for the season with a left knee injury. He tore the anterior cruciate ligament in the knee in Week 5 last season.
"I think he was playing at a defensive player of the year-type of level," coach Gary Kubiak said Monday. "Then here he goes again, he's got to go through this.
"So I know it's very difficult for him ... [and] I know Cush will do everything he can to get back. But you hate to see anybody go through that especially twice now."
On Sunday, Cushing vowed on Twitter that his latest injury setback won't keep him from coming back next season.
It's not how many times you fall down but how many times you get back up. Life is tough but I'm the toughest SOB it's ever seen. Ill be back
— Brian Cushing (@briancushing56) October 21, 2013
The Texans signed Cushing to a six-year contract worth $55.6 million before this season.
Information from The Associated Press was used in this report.