It was an all-too-familiar scene for Willis McGahee.
NFL.com's Dan Hanzus, citing a report from Fox Sports' Jay Glazer, later reported that McGahee suffered a torn right MCL and right lower leg fracture on the play.
According to ESPN's Adam Schefter and Chris Mortensen, the injury is expected to sideline McGahee for 6-8 weeks. McGahee should also avoid placing weight on the injured leg and will require crutches for some time.
The injury represents a terrible blow to the Broncos' offense, an offense that is arguably among the best in the league.
There is some good news, however.
Schefter also reports that McGahee is not expected to require surgery. Additionally, this injury is not to the same knee that McGahee injured in 2003.
During the 2002-2003 Fiesta Bowl as a member of the Miami Hurricanes, McGahee famously tore three ligaments in his left knee: the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) and medial collateral ligament (MCL).
It almost makes a mere torn MCL seem like a walk in the park.
Unfortunately, it isn't.
The MCL, like all ligaments, is a band of tissue vital for coordinating and stabilizing the motion of the two bones it connects. In this case, the bones in question are the femur (thigh bone) and the tibia (shin bone).
The MCL connects the inside portion of the bottom part of the femur to the inside portion of the top part of the tibia. To do so, it must run across the knee joint itself. That is what leaves the MCL so vulnerable to injury in contact sports such as football.
When an athlete is tackled in the manner that McGahee was tackled, the knee is forced inwards by a hit from the outside. This force causes an abnormal bend to the knee, creating an inward angle and thus lengthening the distance the MCL is required to cover in order to connect the femur and tibia.
To do so, the MCL stretches.
However, if the inward force is strong enough, it overloads the MCL's ability to accommodate and a tear results.
Without an intact MCL, there is no safeguard against the inward bending of the knee. Any inward force can therefore cause the knee to buckle and suffer further damage, meaning the knee is severely unstable.
That also means that McGahee's ability to cut, change directions, and balance are severely compromised until the injury fully heals.
If that is not enough, McGahee also fractured either his tibia or fibula, the two bones that make up the lower leg. While exact details are scarce, one can speculate that the hit to the outside of his knee fractured the top of his fibula, the small bone that runs on the outside of the lower leg alongside the tibia.
As mentioned, neither injury requires surgery.
In fact, most MCL injuries do not require surgery and heal well with immobilization, rest and physical therapy, whether they are grade 1 (over-stretched but no tear), grade 2 (partial tear) or grade 3 (complete tear) injuries. One can assume that McGahee's fracture is not displaced sufficiently enough to require surgical realignment and will thus heal properly on its own.
As one can see, it could be worse.
When an athlete is tackled in a way that his or her MCL is torn, two other tears often accompany the MCL injury.
One is the dreaded ACL tear.
The ACL runs from the mid-lower to outer-upper corners of the inside of the knee joint. For that reason, inward force to the knee can similarly stretch or tear the ACL along with the medial meniscus, or the cushion between the inner portions of the femur and tibia.
McGahee did not suffer such additional injuries that would require surgery and rehabilitation for possibly up to an entire year.
Makes 6-8 weeks seem not so long, doesn't it?
The Broncos think so, too. They will not place McGahee on injured reserve, according to the Associated Press.
UPDATE: Wednesday, Nov. 21 at 1:37 p.m. ET
Gregg Rosenthal of NFL.com, citing a report by Fox Sports' Jay Glazer, reports that the Broncos will, after all, be placing Willis McGahee on injured reserve, effectively ending his regular season.
However, according to ESPN's Adam Schefter, this move was made so that McGahee would be eligible to return to play by the week of the AFC Championship game:
IR for Willis McGahee expected as @jayglazer reported. But it would be with designation to return so he could play in AFC Championship game.
— Adam Schefter (@AdamSchefter) November 21, 2012
However, the Broncos are fully expected to make the playoffs this season and perhaps as far as the AFC Championship or Superbowl.
If he is healthy, they want to make sure McGahee accompanies them.
---End of Update---
The author of this article is a soon-to-be Family Medicine resident physician with plans to specialize in Primary Care (non-operative) Sports Medicine. The injury information discussed above is based on the author's own anatomical and clinical knowledge. Additional information can be found in Dr. Jonathan Cluett's article on MCL tears here.