Packers quarterback Jordan Love has an MCL sprain. We asked a medical expert about MCL injuries, severity, treatment and timetables.

Is it common for a professional athlete to have the option of returning just 10 days after a medial collateral ligament sprain?

Green Bay Packers coach Matt LaFleur didn't close the door on Jordan Love being available for Week 2 against Indianapolis after the injury he suffered against the Philadelphia Eagles in Friday night's loss .

It seems unlikely that he'll suit up as soon as Sunday, and that it's far more likely that he misses a couple games, but by now everyone realizes the MCL injury is a far better outcome than an ACL tear. So what do the different ligaments do, what's the rehab process like, could he play with a brace and what else should we know about the injury?

Dr. Mark Wichman, an orthopedic and sports medicine specialist with Aurora Health Care, offered some insight, although he doesn't have firsthand knowledge of Love's specific injury and treatment.

What is the MCL and what does it do?

The medial collateral ligaments on the sides of the knee, connecting the femur and tibia, protect the knee from being stressed into knock-knee or bow-legged positioning. They essentially protect the outer sides of the knee and maintain ease of side-to-side movement, whereas the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) protect forward and backward movements. The MCL is injured more commonly than the ACL.

"In most of the instances where I've treated MCL (injuries) throughout my career, a week to 10 days (for return) is a possibility with a very low-grade sprain in a forward and backward player like a lineman," Wichman said. "But pivoting, twisting, cutting … it's position-dependent. A cornerback, a linebacker, a receiver, quarterback, those positions require unpredictable pivoting, twisting, cutting in different directions."

In other words, he'd forecast a couple weeks minimum to return from an MCL sprain at those positions on the field.

Most of the MCL fibers aren't inside the knee joint and that means, many times, athletes won't even have swelling in the knee.

"That's important here because, if you have a big, swollen knee, that almost always requires many weeks just for the swelling to come down and more weeks to rehab the knee and get the player back on the field," Wichman said. "With a low-grade, often there's little or any swelling in the joint. It is easy to recover from and less painful."

What are the degrees of MCL sprain and how badly was Jordan Love hurt?

We don't know the severity of Love's MCL sprain, but we can assume it's a lower-end strain, since the Packers aren't willing to put him on injured reserve and commit to him missing the next four games.

The sprain — which is synonymous with a tear — can be Grade 1 (least severe), Grade 2 or Grade 3, based on the severity or stretch and tearing of the ligament fibers.

"Grade 1, there is minimal swelling. There is minimal instability," Wichman said. "It feels sort of normal just painful when you stress it. … Grade 3 is a fairly dramatic, where the ligament itself has completely lost its continuity."

Social media reacts: NFL world grateful that Jordan Love's injury isn't worse

Could Jordan Love wear a brace on the knee?

Wichman said, "Most MCL braces are hinge braces that have a stay on the inner side and the outer side. They can give protection to the collateral ligaments while still allowing the knee to straighten and flex almost fully. It is possible to provide a brace for an MCL way more effectively than for an ACL. We have them but they're not nearly as effective (for the ACL)."

Didn't it look like Jordan Love's knee 'popped' during the injury?

Video began circulating after the Love injury that showed what appeared to be movement inside the knee, more or less a ligament "popping." Fans took that as a terrible sign.

But Wichman said that's not uncommon with an MCL, and that the observed buckling is called a "valgus."

"You can get a pretty good pop from an isolated MCL," Wichman said. "A player comes off the field and tells you, 'Doc, I felt a pop in my knee.' A pop is not unique to the ACL or MCL."

He said it wasn't unusual for players to believe they had torn an ACL, only to discover it was the MCL. The best Wichman could tell, based on the injury and the team's reaction to it, it's likely "a pretty straightforward low-grade MCL" that would be classified as either Grade 1 or Grade 2.

What's the rehab process for an MCL strain?

Wichman said the rehab focuses on minimizing the swelling, maintaining range of motion and staying in shape until it heals.

"They don't want it to rest so much that his quad or hamstrings start to shut down, so they'll need to keep his muscles in tone, so when the day comes that he's able to practice again, he's not de-conditioned," Wichman said. "Avoiding de-conditioning of the leg is what professional athletes get that we don't get (as normal people). We might go to PT a couple weeks, twice a week, and wouldn't be doing anything else (on the other days)."

This article originally appeared on Milwaukee Journal Sentinel: Packers quarterback Jordan Love has an MCL sprain. We asked a medical expert about MCL injuries, severity, treatment and timetables.