Arian Foster is helped off the field by center Ben Jones and an unidentified team member. (AP Photo/Wilfredo Lee)

The Texans added a major injury Sunday to the massive insult of a blowout loss to the Dolphins. Running back Arian Foster, a key offensive weapon, tore his right Achilles tendon and is out for the rest of the season.

Foster went down in the fourth quarter without contact, and he was carted off the field. After the game, in which Houston fell behind by 41-0 at halftime before losing to Miami, 44-26, several reporters offered confirmation of the severity of his injury.

The four-time Pro Bowler faces a lengthy rehabilitation, and it is reasonable to speculate that he may have played his last game for the Texans, if not in the NFL entirely. Foster will be 30, which is old for a running back, when next season begins, and he will be in the final year of his contract, one that will carry a cap hit of over $9 million if Houston keeps him without re-negotiating.

In addition, Foster has a lengthy history of soft tissue injuries, including a groin tear that forced him to miss this season’s first three games. Going back to his college career at Tennessee, the running back has suffered major injuries to his shoulder, ankle, knee, back, calf, hamstring, groin and now Achilles.

When on the field, Foster has proven to be one of the best in the NFL at his position. Despite entering the league as an undrafted free agent in 2009, he was a first-team All-Pro in 2010, when he led the NFL in rushing, and has rushed for at least 1,200 yards and eight touchdowns in each of the four seasons in which he played over half the games.

When Foster was out earlier this season, Houston turned to a pair of backups, Alfred Blue and Chris Polk, neither of whom looked particularly impressive. The injury adds to a season that has gotten off to a tough start for the 2-4 Texans, who next play the Titans and then will likely be very happy to have a bye.