A lot of what the Bears’ offensive line looks like in 2018 depends on what they decide to do with four-time Pro Bowl OG Josh Sitton.

If the Bears pick up his $8 million option by March 9, Sitton is still an above-average starter, but he will be 32 in June and is no longer a Pro Bowl-caliber player. Injuries kept him out of three games last year and limited him in a couple others. Sitton’s last Pro Bowl season was 2016, when he went as an alternate.

Injuries could also determine what kind of performance the Bears get at the other OG spot, where Kyle Long missed the first two games in 2016 after offseason right ankle surgery and the final four with multiple injuries. He had neck surgery in December and indicated on social media that he was only one-third through his anticipated medical procedures. The three-time Pro Bowl pick played the 2016 season with a torn labrum in his left shoulder, and he suffered tendon and ligament damage to his left hand in a midseason game. Long’s last Pro Bowl season was in 2015, when he went as a right tackle.

Cody Whitehair has started all 32 games since the Bears drafted him in the second round in 2016, including 28 at center, the only O-line position he didn’t play at Kansas State. Whitehair has the versatility to play any of the interior line positions, but given the uncertainty with Sitton and Long, some insurance/depth is needed. Their top OG backup, Eric Kush, could be that guy if he’s completely recovered from last year’s torn hamstring that ended his season in August. He started four games for the Bears at left guard in 2016.

Backups Tom Compton and Bradley Sowell started five and two games, respectively, last year when injuries mounted, but both are unrestricted free agents. Jordan Morgan, last year’s fifth-round pick, redshirted on injured reserve and remains a project.

Outside, LT Charles Leno was locked up last offseason with a four-year, $37-million extension through 2021. He’s a player you can win with but not because of. RT Bobby Massie is serviceable, especially as a road grader in the run game, but he sometimes struggles with speed in pass pro.

Depth is thin outside, although most of Sowell’s playing time has been at tackle, where he started nine games for the Seahawks in 2016, including six on the left side. He started one game at left guard and one at right tackle last year.

Given the financial commitment to Leno, the Bears would be more inclined to upgrade on the right side, where Massie is in the final year of his contract. The Dolphins’ Ja’Wuan James is about the only available right tackle who would be a clear upgrade, especially in pass protection, and he’s just 25. Even though James missed the last half of the 2017 season with a groin injury, the former first-round pick could be out of the Bears’ price range, unless they part ways with Sitton.

The Panthers’ Andrew Norwell is the best of the interior linemen available, but the Bears don’t figure to be the team that makes him the highest-paid guard in the NFL. Interestingly, there are three guards ready to hit the market who were selected within the first 12 picks of the 2013 draft. None of the three — Luke Joeckel (second overall), Jonathan Cooper (seventh) and D.J. Fluker (11th) — are very good.

The Bears might be more inclined to add offensive linemen through the draft, and they could use their eighth overall pick to get Notre Dame guard Quenton Nelson, who is considered as close to a sure thing as there is. He’s a plug-and-play starter from Day One who some analysts believe can be a Pro Bowler as a rookie. Nelson was mentored in college by new Bears O-line coach Harry Hiestand.

Another Hiestand protégé, tackle Mike McGlinchey, isn’t as highly regarded as Nelson, but he would be a steal for the Bears in Round Two.

Three other potential first-round tackles -- Texas’ Connor Williams, Oklahoma’s Orlando Brown and perhaps Oregon’s Tyrell Crosby -- aren’t considered top-10 picks. But, like McGlinchey, if they fell to the Bears’ 40th overall spot, they’d be tough to pass up.

Brandon Parker paved the way for Tarik Cohen for three years at North Carolina A&T, and he could be worth a late pick as a developmental project.

If the Bears pass on Nelson with their first pick, they can still address the OG position early with Georgia’s Isaiah Wynn in Round Two if he's still available. The 42-game starter doesn’t have the dominant size Nelson possesses, but he may have better movement skills and still plays a physical game.

Iowa’s James Daniels is the top-rated center if the Bears decide to go that way, which would allow Whitehair to move back to guard, if Sitton is gone. Daniels is a third-year junior who is still growing and maturing. He could also project to guard, giving his pro team some position flexibility.