Allen suffered an MCL sprain in Saturday's preseason game against the Cardinals.

It's unclear how severe the sprain is, but if it were to carry into the regular season, the team would likely need to consider other options at right guard.

Allen will have surgery on his elbow, is out against the Broncos on Sunday and will likely miss the remainder of the season, Terez A. Paylor of the Kansas City Star reports.

Allen's injury will thin the offensive line out even more, with Donald Stephenson already missing the first four weeks due to a suspension. The injury could directly impact the production of the offense, with backups now opening holes for Jamaal Charles and protecting Alex Smith.

Allen (elbow) didn't practice Thursday and is questionable for Sunday's game against the Broncos.

Allen would be another big blow to the offensive line that is already thin. If he is out, the Chiefs will have an even tougher time opening holes for Jamaal Charles and protecting Alex Smith.

Chiefs LG Jeff Allen and RT Donald Stephenson worked with ex-NFL C LeCharles Bentley during the offseason.

Bentley's career was wrecked by a knee injury after six seasons, but he started all 57 games he appeared in and made two Pro Bowls. He now runs an offensive lineman performance academy and works with NFLers. Allen is coming off a down season, and Stephenson is stepping into the starting lineup after being the Chiefs' swing tackle in 2013. Kansas City's line is experiencing some turnover.

Chiefs LG Jeff Allen was forced from Thursday's game against the Eagles with a right groin injury, and is doubtful to return.

Allen departed in the fourth quarter, and is almost certainly done for the night. He's been replaced by Geoff Schwartz.

Chiefs LG Jeff Allen was carted off the practice field with a right shoulder injury Saturday.

Beat writer Adam Teicher hints that Allen could miss significant time. Last year's No. 44 overall pick out of Illinois, Allen started 13 games as a rookie and is competing with Geoff Schwartz for the starting job this summer.

Chiefs 2012 second-round pick Jeff Allen shuttled between tackle and guard at the team's pre-draft minicamp.

Allen was a left tackle at Illinois and started at left guard last season, grading as Pro Football Focus' No. 79 guard out of 81. He's only 6-foot-3, 307, so perhaps the new staff practiced Allen at tackle because they were short on bodies. Eric Winston has been released and Branden Albert was an expected no-show.

Chiefs LG Jeff Allen left Thursday night's game against the Chargers with a possible concussion.

Allen exited early in the second quarter. He was thrust into the starting lineup in Week 3 after Rodney Hudson was hurt and sent to injured reserve. Allen, a second-round rookie, was replaced in the lineup by veteran Russ Hochstein.

Chiefs second-round OG Jeff Allen (ankle) has resumed practicing.

Allen was believed to have a high-ankle sprain after sporting a walking boot in late May. It turns out the injury wasn't quite as serious after all. Expected to play an interior swing role, Allen should be 100 percent for training camp.

Chiefs second-round OG Jeff Allen is sporting a walking boot at OTAs.

A walking boot doesn't necessarily mean a high-ankle sprain, but that's often the case. The Chiefs' last offseason practice is June 15, so Allen may not be back until training camp. Allen is expected to come off the bench as a rookie.