On Saturday night, a nightmarish scene unfolded for St. Louis Rams fans when quarterback Sam Bradford went to the turf with an apparent knee injury, one that eventually received the dreaded torn ACL diagnosis. The tear represents his second such injury—to the same knee, no less—in under 12 months.
Nevertheless, optimism reigned supreme during the initial hours following the injury. According to ESPN's Adam Schefter, initial tests "did not show damage" to his ACL:
Throughout the morning and early afternoon on Sunday, however, that optimism began to slowly erode away. First came a second report from Schefter stating Bradford's ACL remained a concern:
Not long after, the bad news officially hit—this time, from Schefter's colleague Chris Mortensen:
The sequence of events leading up to the eventual diagnosis surely left many confused, serving as a reminder that NFL injuries can remain a bit of a mystery all the way up until an official team announcement. Making an accurate diagnosis always requires time, precise evaluation and re-evaluation.
To make sense of what happened, let's take a closer look at the anatomy, mechanism of injury and events that followed, starting with the injury itself.
The Anatomy and the Injury
Normally, the ACL runs through the center of the knee and prevents the tibia—the shin bone—from moving forward or over-rotating with respect to the thigh. When the joint moves in such a way that the ACL's connection points on the femur—the thigh bone—and tibia move further away from each other, the ligament can tear.
A classic mechanism of injury leading to an ACL tear involves a direct blow to the front or outside of the knee, forcing it to hyperextend or twist inward.
As seen, Cleveland Browns lineman Armonty Bryant likely falls into the outside portion of the front of Bradford's knee. The quarterback's knee hyperextends as a result of the hit, likely causing the tear.
In Bradford's case, the injury represents a tear of a ligament graft, not his native ACL. He went down with his first left ACL tear in October 2013 and underwent surgery thereafter.
During the operation, doctors likely used a piece of his patellar tendon—the part of the knee a doctor hits with a reflex hammer—to replace his injured ligament.
Initial Evaluations and Apparent Optimism
Following an injury concerning an ACL tear, an athletic trainer or doctor can employ a few simple physical exam techniques that can strongly hint at or against an ACL tear.
More than likely, Schefter's initial tweet suggested those physical exam maneuvers seemed negative—or reassuring against a tear—following the injury. Two such tests include:
- Anterior drawer test: With the athlete lying on his or her back, the examiner bends the knee, plants the foot on the ground and attempts to pull the tibia forward.
- Lachman test: With the athlete lying on his or her back, the examiner lifts the injured leg up, grasps above and below the knee and attempts to pull the tibia forward.
If the examiner is able to pull the tibia significantly forward with either the anterior drawer or Lachman tests, an ACL tear becomes a strong possibility. On the other hand, no motion at all suggests an intact ligament.
Both maneuvers do their job very well—especially the Lachman. In fact, positive tests can all but make the ACL tear diagnosis, even without an MRI.
That said, neither test is perfect—even in the best hands practicing the best medicine, as is most definitely the case with the Rams. Sometimes, the MRI simply tells another tale.
Sunday's Follow-up Reports
As mentioned, Rams fans likely went to bed with a bit of reassurance on Saturday. After all, head coach Jeff Fisher mentioned—via NFL Network's Ian Rapoport—Bradford was "walking around fine" following the injury, adding that he would undergo more testing the next day.
Regrettably, the ability to walk in a straight line does not necessarily imply an intact ACL. Pivoting and changing directions becomes quite difficult, but an athlete walking away from a tear is not an uncommon scenario.
When the concern for Bradford's ACL resurfaced, it likely did so as a result of one of two possible developments:
- Re-examination by the Lachman or anterior drawer tests demonstrated the development of laxity—or looseness—in the knee, and an MRI confirmed the tear.
- MRI findings suggested the tear despite reassuring tests.
The exact sequence of events remains a bit unclear.
Whatever actually transpired, the bottom line is simple: Bradford will miss the entirety of the 2014 season and likely go under the knife fairly soon. The injury represents a brutal and devastating—almost unfair—blow to both the quarterback himself and the up-and-coming Rams, who looked to remain competitive in the otherwise strong NFC West.
The entire NFL and its fans surely send the former Oklahoma Sooner their best wishes as he starts down the road to recovery once again.
Dr. Dave Siebert is a second-year resident physician at the University of Washington and a member of the Professional Football Writers of America. He plans to pursue fellowship training in Primary Care (non-operative) Sports Medicine.