Thatcher Demko's injury has been revealed by NHL.com reporter

"There's a lot of uncertainty around this, around this injury, and as much as he believes he can get to 100% and seems to be in a really good place the past couple of weeks, after, as he said, a month off there remains a lot of uncertainty about the injury. The one thing I can clear up, one thing in terms of the uncertainty, there's no longer uncertainty about what it is. So you guys can get your Web MD out and look up Popliteus." Woodley said.

He added, "It is a thin triangle-shaped muscle behind the back of the knee. And that, evidently, is where the injury has occurred. Whether it's a tear, to what degree, we don't know, but this is basically a muscle deep behind under several layers of other muscles deep on the back of your knee. It doesn't do much. It sort of attaches to the top inside of the femur and then back to the tibia on the top of the other side. For runners, it's what unlocks the knee joint from straight, it's actually a pretty negligible effect on the flexion of the knee, but it pulls the lateral meniscus back and out of the way of flexion. It is a small but somewhat significant ligament, and I'm not sure the degree of the damage or whether he's pulled it off the bone at the ligament, or what, but it is super rare. I've talked to a couple of people that have been doing this at the NHL level for 30 years. They've never seen it. So everything they're telling us tracks, and despite it being small and somewhat insignificant, there's obviously uncertainty that comes when there's no sort of prescribed way to either improve it. Like, literally when you first look it up, one of the first things you'll see is the sort of healing time is anywhere from three to 16 weeks. So, nothing like nailing it down, right?"