Astros' Escalona to undergo Tommy John surgery

Houston Astros pitcher Sergio Escalona needs Tommy John surgery and will miss the entire 2012 season.

Escalona underwent an MRI exam on Friday, revealing the torn ulnar collateral ligament in the left-hander's elbow. The procedure will be performed next week in Houston.

The 27-year-old southpaw was 2-1 with a 2.93 earned run average in 49 relief appearances for the Astros last season.