Late Tuesday night, Indianapolis Colts general manager Chris Ballard conducted a news teleconference in hopes of clearing up the mystery surrounding star quarterback Andrew Luck's long lingering left leg injury.

Ballard admitted that while Luck's medical team once believed the quarterback was solely dealing with a calf injury, they recently discovered he was also dealing with an ankle injury as well.

They thought at first that the injury might have something to do with the os trigonum, a small, back-of-the-ankle bone that most humans don't even have. While Luck indeed has the rare and useless bone, a recent test has led them to believe it is not the source of Luck's issues.

Instead, they believe Luck is dealing with an issue at the front of his ankle, high in the joint, that has been causing pain in his calf and lower leg, above the Achilles tendon.

Armed with the latest information the Colts have provided, IndyStar spoke with a pair of doctors -- Dr. Jonathan Shook, an orthopedic physician specializing in sports medicine at OrthoIndy and Dr. Jan Szatkowski, an Indiana University School of Medicine assistant professor of clinical orthopedics with an expertise in foot and ankle trauma surgery -- to get their opinion on what Luck is facing and how the Colts move forward.

Neither Shook nor Szatkowski have treated or examined Luck.

Question: If the Colts are correct about the problem area being in the front of Luck's ankle, what might the injury be?

Shook: I think the thing about the front of the ankle is actually above the ankle, not directly where your ankle bends but above that where the tibia and fibula come together. That’s where there are these set of ligaments and a thing that’s called a syndesmosis -- that’s a membrane as well as ligaments that hold the tibula and fibula together so they don’t spread apart.

Szatkowski: High ankle spraining (has to do with) syndesmosis ligaments around the ankle. ... Football players and other athletes, soccer players, tend to injure these ligaments around the ankle. They take a long time to rehab and if you go back to (your) sport too soon, you risk this becoming a chronic injury.

Q: This is what you believe the Colts think the injury is now?

Shook: I think so, yes. That makes sense for the type of things they’ve been discussing.

Q: Can you explain how the calf or the back of the ankle is affected by this issue in the front?

Szatkowski: I think the calf strain could have been a distracting injury. When someone has an injury to the calf, their muscles are weaker and they are more predisposed to having an ankle injury.

Shook: I would look at it more like this: It’s not in the front. It’s not in the back. Syndesmosis are actually between these two bones, so it could present, ‘Oh it’s in the front, no it’s actually in the back,’ because that ligament is in the middle. It’s between the two bones. The calf is in the back, so you’ve actually got musculature in the ankle in the front, so it could present pain on both sides, front and back.

More on Luck's injury:

Q: Have you dealt with this type of injury before?

Shook: I mean, if you’d call it a high ankle sprain, I’d say definitely yes.

Q: Would you call what they’re describing a high ankle sprain?

Shook: I would.

Q: OK, so now what?

Shook: So when you think of ankle sprains, there’s the classic low ankle sprain, that’s when someone rolls their ankle and they sprain the ligaments that are on the outside, generally. That’s something you can brace or tape and play through it pretty easily. A high ankle sprain, there’s really no brace that works well to hold that stable, because you’d have to compress the bones side to side toward the middle, so that they’re not splitting apart. Think of the foot kind of trying to drive itself like a wedge between these two bones and they’re splitting apart every time you put weight on it. And then you add a twisting to it, then you’re stressing the ligaments and that tissue even more.

Q: What can be done about that?

Shook: Generally, when there’s weight-bearing, like he’s been doing, it’s about avoidance of activities like hard push-offs, the hard landings, things like that. These are situations where sometimes if they have a complete tear of these ligaments and the tissue between, this is where they actually put screws or devices between the two bones to hold them together while the ligament and the tissue heals. Now I don’t think his is torn all the way. That’s why they haven’t gone to that. It’s the straining and stretching of those ligaments but not a complete tear.

I would say they’re pretty committed to rehab, and again, if he didn’t have a definitive tear that needed to be fixed, then I don’t see why you’d commit to any sort of surgical option at this point.

Q: How could you tell if there was a complete tear or just straining and stressing?

Shook: They probably did an MRI and saw some swelling or edema in that area of the ligaments, and they probably have been doing some functional tests. What would happen is you would hold or stabilize the lower leg bones and you’d take the ankle and twist it in and out, left and right, to see if that’s causing pain by separating those two bones.

Q: Is it common for this type of injury to linger for as long as it has? And is it common for it to appear as only a calf injury and for it to develop into a high ankle sprain?

Shook: They certainly last a lot longer than your typical low ankle sprain. Some of these, it’s not uncommon for an athlete to battle these throughout an entire season, because they kind of keep aggravating it. I’d say some people could go six months with this being a problem. I’d tell you the fact that this course has taken longer than people thought it should, it does kind of play into the narrative of, yes, it’s getting more into this high ankle sprain, this thing we expect to take longer.

I don’t know if there was one injury that beget the other, but I wouldn’t say he had the calf injury and now all of a sudden he has a high ankle sprain. I don’t see a correlation between that. I think it was probably a common injury that kind of resulted in both things being aggravated. … I’m not sure if I’ve ever seen someone rehab from a calf injury all of a sudden get a high ankle sprain. It’s generally not the way it works.

Q: So do you believe this is wear and tear, cumulative type of injury? Or is this the type of injury that happens after a specific incident?

Shook: There’s actually two different ways that this could happen. If he’s had recurrent ankle sprains, then this could be both more of attritional or wear and tear of these ligaments, and the syndesmosis that’s between there could have been stretched out over time. I would think that for him, the ligament is constantly getting cut and rolled on and making him have those problems recurrently. Maybe it’s the way he’s been tackled or sacked, he’s gotten his ankle rolled up underneath him, that’s been where he’s had those prior injuries. It takes a little bit more to tip that balance from being able to play through it to you can’t (play through it), and that’s what shut him down potentially.

Q: So what would an MRI show on an ankle like Andrew’s? Would the straining and stressing or tearing be pretty clear?

Shook: No. Not in the way you’d say for someone who gets an MRI for an ACL tear. That’s a pretty cut and dry reading. It’s either torn or it’s not most of the time. For this, because this syndesmosis or this set of tissue extends over a long distance between the two bones, you could have areas that might be fine and areas that are not fine. So you’d be looking throughout that to see if there’s a little bit of tearing here whereas in the other 90 percent of it, it looks fine. Or maybe it 50 percent looks bad and the other half looks good. It’s not an all or nothing proposition like it is for ACLs.

Q: Can he or he play on it? Or could he do more damage to it?

Shook: I think he could certainly prolong the healing of this or prolong the recovery by going before he was ready. Just remember, this is not something that’s really brace-able like a low ankle sprain or any other joint that you can put something on to stabilize it. There’s not good way to do that. He either has to be confident and ready and painless or it’s just going to be how it is throughout the game.

Szatkowski: You don’t want an athlete to come back too soon, and I think that’s one of the most common errors made, coming back before he’s ready and there's a lot of pressure. Everyone has to be making a team decision for him. ... If you go back to sport too soon, you risk this becoming a chronic injury.

Follow IndyStar Colts Insider Jim Ayello on Twitter, Facebook and Instagram: @jimayello.

Contact IndyStar reporter Shari Rudavsky at 317-444-6354 or shari.rudavsky@indystar.com. Follow her on Facebook and on Twitter: @srudavsky.