In the second inning against the Pittsburgh Pirates, Montero was attempting to run out a grounder to the pitcher. It appeared that he landed awkwardly while trying to avoid the tag, resulting in the injury to his knee.
According to Associated Press reports, Montero described the feeling as "at that moment I just felt something pop." A look at the video replay of the incident seems to show Montero pulling up ever so slightly, with his right leg landing such that the knee rotates inward. Montero then hobbled off the bag, grabbed hold of his knee and bent over at the waist, clearly uncomfortable. Although he was able to walk off the field under his own power, the injury signaled the end of Montero's evening.
An MRI taken after the game Saturday indicated a meniscus tear, which will require surgery. The team will not yet speculate on a timetable for a return, as Montero is undergoing further evaluative tests Monday.
An arthroscopic procedure to address a meniscus tear would typically require anywhere from 3-6 weeks before returning to play. The timetable depends to some degree on the nature of the surgery. In the case where a small flap of torn meniscus is removed (meniscectomy), the recovery is somewhat quicker. If the injured meniscus is repaired, the knee has to be protected longer (meaning activity has to be controlled for a more extended time) to allow the repair to heal.
Either way, Montero's case is made more complicated by one thing in particular: his position.
As a catcher, he has to spend a significant amount of time in a deep squat, a position that requires not only full range of motion of the knee but also the ability to bear the weight of the body while fully flexed. Catchers also have to explode quickly out of their stance to make defensive plays. That action demands strong contraction of the quadriceps, the muscle on the front of the thigh.
Following any knee surgery, both range of motion and quadriceps strength are impaired. It takes time to eliminate swelling and restore full function around the knee. While a player at another position might be able to get away with returning from this procedure at less than 100 percent, it's just not possible as a catcher due to the unique demands of the position. Beyond his position-specific demands, Montero will also need to be able to turn on the knee to swing the bat as well as run the bases without hesitation before he can return.
Even if Montero's injury turns out to be "just" a meniscus tear, plan on his being sidelined for at least six weeks. Chris Snyder will serve as the starting catcher while Montero is out.