Jordy Nelson's hamstring injury might just be the gift that keeps on giving.
Nelson missed significant time this season due to a hamstring strain that first held him out in Weeks 8 and 9, and then from Week 14 through 16 following a re-injury, according to the official NFL inactive list. He returned to the field Week 17.
Yet the story does not end there.
Though now on the Green Bay Packers (11-5, 3rd seed in NFC) injury report due to a knee injury, Nelson's current condition might be directly linked to the hamstring injury that has plagued him all season.
As I wrote a few weeks ago, hamstrings can be extremely sensitive to re-injury, and playing through a hamstring injury is risky. An aggravated hamstring is prone to further, more serious injury.
That might be what happened to Nelson in Week 13.
However, hamstring injuries can also affect the rest of the legs.
Though a player may not be aware of it, a hamstring injury can affect his gait—how he walks and runs. For example, his stride length can be made uneven by a weakened hamstring.
In other words, even though he may not have felt it, Nelson ran differently Week 17.
Will Carroll, injury expert for Sports Illustrated, noted Nelson's altered gait during a long catch he made at an all-out sprint:
Jordy Nelson isn’t 100 percent yet. On his long TD, he was taking shorter strides on the affected side. He was still fast enough to outrun the defenders. He had a minor knee injury during the game, but there was no information at this time on specifics.
While no reports surfaced about further hamstring injury, Nelson missed a few plays due to the knee injury that Carroll mentions.
That knee injury is almost certainly related to his hamstring.
When a player of Nelson's caliber sprints or cuts, he places incredible amounts of stress on his legs and knees. However, the muscles and ligaments being used adapt to this stress during years and years of strength training and conditioning.
This adaptation helps prevents the injuries that would otherwise occur to less-conditioned athletes.
Now, throw in a sudden, unexpected hamstring strain such as Nelson's into the equation.
When muscle strains occur, they weaken the injured muscle. They also produce pain. However, pain and weakness can resolve at different rates as an athlete heals.
It appears that despite no longer being painful, some of Nelson's hamstring weakness still remained on Sunday. As Carroll mentioned, it shortened the step length on his injured side compared to his healthy side.
His knee might have felt that change.
Though this represents pure speculation, as exact medical details are unavailable, the previously mentioned years and years of muscle and ligament adaptation cannot immediately change to accommodate a suddenly altered gait.
Nelson's slightly changed stride length placed a different set of stresses on his otherwise strong and sturdy knee ligaments during Week 17, stretching the ligaments in a way that varied subtly from what they are used to.
Fortunately, that difference appears to be extremely small.
According to the Packers official Twitter account, Nelson practiced fully on Thursday:
McCarthy-Full participation in practice today by WRs Jordy Nelson and Randall Cobb, both looked good. #Packers— Green Bay Packers (@packers) January 3, 2013
That said, doctors will certainly evaluate his knee following practice as well as later this week. They will perform a number of motion tests on his knee, tests that produce pain if a ligament is truly injured.
Swelling later in the day following practice would also imply ligament damage rather than merely discomfort stemming from a slight gait variation.
Nevertheless, for now, all signs point to Nelson being active this week.
That is great news for the Packers, who are getting healthy at just the right time.
It is also terrible news for the NFC, as a great offense is getting even greater.
...As if Aaron Rodgers needed yet another fully healthy, elite offensive weapon at his disposal.
Dave Siebert is a medical/injury Featured Columnist for Bleacher Report who will graduate from medical school in June. He plans to specialize in both Family Medicine and Primary Care (non-operative) Sports Medicine, and injury information discussed above is based on his own knowledge.