Stop us if you've heard this one before: The health of a quarterback has put the Minnesota Vikings' present and future plans on hold.

For the past two weeks, Sam Bradford has struggled to get on the practice field due to swelling and pain in his left knee. The issue first arose on the Tuesday following Minnesota's season opener, though the team gave little indication as to the severity at the time. An MRI revealed no structural damage but failed to identify the exact cause of the discomfort. The coaching staff limited his practice to give him the best opportunity to recover while preparing him for Week 2 tilt with the Pittsburgh Steelers. All the while, the Vikings expressed optimism that Bradford would suit up on game day.

However, Bradford's knee did not respond as the medical staff hoped during the pre-game workouts, forcing the Vikings to turn over the offense to journeyman signal-caller Case Keenum. Just one week after scoring 29 points, the Bradford-less offense fell apart in a difficult 29-9 defeat.

The Vikings went into information-lockdown mode in the aftermath of Bradford's surprising appearance on the inactive list. Head coach Mike Zimmer gave a puzzling assessment of his quarterback's recovery, characterizing Bradford's health as "fine" while suggesting he might not return until "six weeks from now." Zimmer's cryptic evaluation became more confusing still after reports indicated that Bradford has sought out a second opinion from Dr. James Andrews, the sports orthopedist most closely associated with major knee reconstruction.

If Bradford's injury proves significant, it would mark the second time the Vikings lost their starting quarterback to knee surgery since the start of 2016. Just over a year ago, Teddy Bridgewater suffered a grisly non-contact injury during practice that nearly cost him his leg. The incident knocked Bridgewater out for the entire season and continues to keep him sidelined. It also prompted Minnesota to trade a first- and fourth-round pick to acquire Bradford from the Philadelphia Eagles.

The increasingly discouraging developments regarding Bradford's injury has put damper on his Week 1 breakout, perhaps the best game of his NFL career. In front of a national audience, Bradford torched the New Orleans Saints defense for 346 yards and three touchdowns while completing over 84 percent of his passes en route to a 29-19 victory. He flashed the elite arm talent that made him the No. 1 overall pick in the 2010 NFL Draft, fitting passes through tight windows with ease. The dazzling performance earned him NFC Offensive Player of the Week honors and announced the Vikings as contenders. Of course, that status hinges on whether Bradford can return to the field.

Major knee concerns have cropped up numerous times during Bradford's eight years in the NFL. He tore his ACL seven games into the 2013 season, sidelining him for the duration of the year. He rehabbed quickly enough to return for the following preseason only to re-tear the ligament. Bradford's latest injury involves the same balky joint as well, underscoring fears that his knee problems will only worsen with time.

All of which could alter the already difficult-to-project market for Bradford. Due to questions about Bradford's inability to stay on the field and the lack of clarity surrounding Bridgewater, the Vikings emerged from the offseason without a quarterback under contract past the current year. That put Bradford in a predicament similar to Joe Flacco's entering the 2012 season: carry the team to the playoffs and cash in majorly; fail and fight for scraps in another city.

Bradford's performance in the season opener suggested that the Vikings had erred in their judgment, leaving them with little leverage for extension talks with the suddenly red-hot signal-caller. However, after Bradford's knee ruled him out of the two subsequent games and has sidelined him indefinitely, the present and future of the quarterback position looks uncertain in Minnesota.

Those issues under center could derail a team otherwise ready to compete in the NFC. The roster appears flush with field-tilting defenders, particularly among the front four where Everson Griffen and Danielle Hunter can rack up double-digit sacks individually. The front office also invested along the offensive line, a group that features a new starter at each spot. Stefon Diggs has produced like a superstar wideout when paired with a quality passer, and secondary weapons Adam Thielen and Kyle Rudolph gives the air game balance. In the backfield, Dalvin Cook looks like a more-than-capable heir to Adrian Peterson's throne. That supporting cast looks ready to peak now, not in a few years when the Vikings might finally have stability at QB.

If Bradford's knee continues to cost him games or even require surgery, it leaves the Vikings have many options to ponder but no obvious choice. Do they tie themselves to Bradford long term knowing his persistent injury issues? Do they pivot back to Bridgewater, a Pro Bowl quarterback who hasn't taken a live snap since the 2015 season? Should they look for a new starter outside the organization, whether from a reputedly loaded 2018 QB rookie class or a free-agent pool that could include Drew Brees and Kirk Cousins? The right call could put the Vikings on a path to annual title contention. The wrong bet could sink the franchise's best chance at a Super Bowl since Brett Favre's Twin City renaissance ended in the NFC Championship nearly a decade ago.

But those decisions remain months away. Right now, Bradford's health and the Vikings' season hang in the balance.