Colts' Castonzo set to undergo season-ending ankle surgery

Indianapolis Colts head coach Frank Reich has announced left tackle Anthony Castonzo will have season-ending ankle surgery, according to NFL Network's Mike Garafolo.

Castonzo's absence will be a huge blow to a Colts squad fighting for a spot in the postseason.

Indianapolis is currently on the outside of the AFC playoff picture, needing a win over the Jacksonville Jaguars and additional help in Week 17 to secure a postseason appearance.

The veteran left tackle has been limited to just 12 games this season after battling both ankle and knee ailments throughout the year. Castonzo was one of a few linemen who missed last Sunday's contest against the Pittsburgh Steelers. The thin offensive unit gave up five sacks during the bout as a result.

Castonzo has been a mainstay in Indianapolis' offense for much of the last decade, starting 144 games since 2011.

The Colts are reportedly expected to sign tackle Jared Veldheer to compensate for Castonzo's injury, according to NFL Network's Tom Pelissero.