MVK (Most Valuable Knee)
With a distinct lack of position battles, contract holdouts, camp fights, idiotic arrests, and/or verbal gaffes, the media have locked onto the day-to-day status of Brian Urlacher's left knee as the newest source of daytime Bears drama. Up until the moment Urlacher actually participates in the first game against the Colts, there will be a whole bunch of Bears fans filled with anxiety. It's a situation that fans across the NFL face every year in that training camp calm before the regular season storm. How long will we have to live with the fear? The Bears have yet to play a preseason game--we may be in for a long month.
What's the best way to combat that fear? Knowledge, of course, broken down so that anyone can understand the issues at hand with confidence, and promptly ignore all those useless stories counting the days Urlacher doesn't practice. If you simply want an educated guess at Urlacher's prognosis, skip to the bottom of this post. If you want to really understand what going on (so that the next knee injury doesn't freak you out), read on.
Editor: Promoted to the front page from our Fanpost section. Better late than never...
(Nota Bene #1: As I've stated before, I'm not an expert, and I'm working off of limited information stated in public reports. I have no specific or personal knowledge of any Bear's medical status. Everything I write can be culled from medical texts and articles, and applies in general to generic diagnoses. Apologies in advance for sounding too pedantic or too technical--I'm trying to explain this stuff to the layperson as best I can, and it's a fine needle to thread.)
(N.B. #2: I've linked to several sources for those that are curious and want to read further. However, many of the facts and figures I write about come from articles in medical journals available to me only through institutional licenses. Normally, I would cite these articles in a bibliography at the end, but this is a FanPost, and most of the people reading this would be hard-pressed to gain access to these articles. Plus, I'm a bit lazy. Therefore, I've left these citations out, but if anyone is interested, ask me the comments and I'll gladly provide the references.)
Just the Facts:
Here's the sum total of facts specific to Urlacher's situation that I'm working from:
1) From the Bears website:
The Bears received some good news Monday as Brian Urlacher’s MRI exam confirmed a sprained MCL and partially sprained PCL but showed no damage to his ACL, menisci or articulating cartilage.
2) From the Trib:
Urlacher, who attended former teammate Desmond Clark's charity bowling event Tuesday evening, continues to rehab his knee after spraining the medial collateral and posterior cruciate ligaments during the Jan. 1 season finale against the Vikings in Minnesota. He initially was told it would take 10 weeks to stabilize the knee, but there was no need for him to rush back into action.
3) Photos and video of the injury itself:
via Brian Cassella
4) From an ESPN1000 interview: Urlacher stated that he'll be wearing a 14 ounce knee brace throughout the season.
5) From multiple sources: Urlacher has skipped several practices due to soreness. This is obviously what we're all worried about.
6) Finally, there are some facts from what hasn't been reported: a) He never had his knee scoped and there are no plans to in the future; b) other than at initial diagnosis, no further need for MRI has been reported.
When diagnosing and treating sprains, the manner in which the injury occurred is very important. Urlacher's sprain was caught by national television, so that takes a lot of the guessing out of it. As highlighted by the photos, Urlacher's left foot gets caught in an awkward position while essentially doing the splits. Major Wright then gives a nice helping hand by coming down hard on Urlacher and pressing him even further into that awkward split. Because of the weird way Urlacher's left foot/ankle planted on the turf and the way Wright doubled him over, there was no give or slide to that leg (no spray of rubber pieces). The end result is a massive valgus stress (bending the lower leg out laterally in relation to the upper leg) on Urlacher's left knee. This is the source and mechanism of his sprain.
By the way, Urlacher is very fortunate that both his knees were not sprained. If you look at the first picture, you can see that his right foot was planted, but failed to dig into the turf, instead sliding out underneath him (spray of rubber pieces). His weight (and Wright's weight) then transferred harmlessly to Urlacher's butt. Had his right foot stuck, all that force would put similar stress on his right knee.
The Importance of the MCL/PCL
Ligaments (bone-to-bone connectors) provide stability to joints, preventing them from slipping or twisting when stressed. Suffice it to say, the MCL and the PCL are jointly responsible for stability against valgus stress (among other things), hence the reason those two ligaments were injured. Specifically, the MCL has primary responsibility, and the PCL secondary responsibility (the load is split 80/20 to 60/40, depending on how flexed the knee is). This is why the MCL was sprained worse than the PCL.
There is one other important point to get across, however. There are two main sources of joint stability: static (passive) stability provided by ligaments, and dynamic (active) stability provided by the muscles and their associated tendons (muscle-to-bone connectors) pulling over the joints. Obviously, dynamic stability is incredibly important to football players who cut and change speeds at enormous rates. The primary dynamic stabilizer associated with the MCL/PCL and the knee in general are the quads. Remember this when we discuss rehab.
What's the Damage?
Diagnosis dictates treatment and rehab. All sprains involve tearing of fibers in a ligament. They are classified based on the extent of this tearing and the associated amount of laxity (looseness or give) as a result of this tearing:
Grade I) Minimal tearing at the microscopic level, no associated laxity.
Grade II) Partial gross tearing, associated with up to 1cm of laxity (the joint can move up to 1cm more than normal because of this loose ligament)
Grade III) Complete tear, associated with >1cm of laxity
The gold standard for diagnosis involves surgically scoping the knee. However, almost every sprain can be diagnosed with a combination of MRI imaging (determines if there is structurally a full tear or not) and clinical exam (test if there is any laxity at all). With those two pieces of information, you can classify a sprain without surgery. Let me drive that point home, because it will be important later on: for knee sprains, MRI imaging is only required to look at structural issues.
I couldn't find any media reports that give the specific grades to Urlacher's sprains, but my guess is that he suffered a grade III (complete) sprain of his MCL and a grade I or II (partial) sprain of his PCL. The reason I assume a complete tear of his MCL is because he was initially told it would take 10 weeks to stabilize his knee, which is consistent with a grade III sprain.
Again, Urlacher should consider himself lucky. If he had taken more stress and his PCL completely tore as well, then he would have what orthopods like to call a medial column injury, or a grade IV sprain. He would have no residual stability against valgus stress (his knee would essentially swing free laterally--an enormous amount of laxity), and it would likely require graft surgery with a year's worth of rehab to get back to full function.
The Road to Recovery
The first step to healing is the infiltration of fibroblasts (cells that produce scar tissue). These cells constantly produce and remodel scar tissue to mend the broken ligament. The closer the torn ends are to each other, the faster this process happens. Depending on the nature of the tear, this may take a few days to a month. The goal of this passive phase of rehab is to optimize this healing process in order to return full static/passive stability.
The most important thing is to avoid all valgus stress, so a drop-locking knee brace is used to immobilize the knee, along with crutches for the first week or so. Additionally, it is very important to guide the remodeling of scar tissue through gradually increasing passive range-of-motion (ROM) exercises. If this is neglected, and ROM isn't optimized, the healed ligament will be "tight" and can easily tear again. The amount of weight that can be put on the knee is dictated by pain tolerance.
After remodeling, the scar tissue matures, a process that takes 6 weeks to a year. However, by this time, the failure load is the same as normal ligament tissue, so it is okay to begin the active phase of rehab.
After immobilization, the muscles that normally work with and dynamically stabilize the knee (mainly the quads) have atrophied a bit from non-use. While continuing to improve ROM, active rehab now focuses on returning that strength, and the activities that you can do are dictated by how strong the quads are. Stationary biking can be used as soon as ROM reaches 100 degrees. Running can begin once the quads have returned to 60% strength (compared to the other leg). Agility drills are added once the quads have 80% strength. And so on. Urlacher has another whole month to get back to 100% strength, and I have no doubt he'll get there.
Remember, however, that those weak quads are working overtime to maintain dynamic stability in the knee. This leads to soreness, the kind I believe Urlacher is still experiencing. Imagine a single isolated muscle that has to work 2-3 times as hard as every other muscle in your body. You would feel pretty sore as well. That's no reason to be worried, because this kind of soreness is functional, meaning it will go away as the muscle regains strength. The neurons recruiting Urlacher's left quad have to remember how they fired before the injury.
In order to mitigate some of this weakness, a functional hinged knee brace is typically used during rehab (like this one, which also weighs 14oz like Urlacher's). These kinds of braces typically reduce the stress on relevant ligaments and muscles by 20%-30%. Studies on the use of knee braces in rehab are not conclusive, but there's no evidence they increase the risk of injury so they are usually used. There are, however, some commonly reported side effects. The braces change the dynamics of the knee, a situation that the muscles are not familiar with. This may lead to increased muscle fatigue, and therefore soreness. This type of soreness is again functional, and should eventually go away as the quads get used to the brace.
Studies vary widely on recovery times for grade III sprains, with a range from 8 weeks to a full year, but typically center around 10 weeks (hence my assumption that Urlacher suffered a grade III MCL sprain). It's been nearly 7 months since Urlacher first hurt his knee, and many are worried that his continued soreness represents some kind of complication. But we have to be careful about jumping to conclusions. Remember, Urlacher has already demonstrated the ability to cut hard, to accelerate and decelerate, to play at an NFL level. This is clear evidence that structurally his knee has fully healed. With no media reports that another MRI or scope is needed, I have no reason to believe there are any lingering structural issues.
The Long View
There is one small concern that does linger in my mind. Currently, I'm completely convinced that Urlacher's knee soreness is functional, as I've shown above. However, there is another kind of soreness that almost every athlete experiences during and after his/her career: arthritis. The chronic inflammation caused by the overuse of joints eats away at the cushion of cartilage, eventually leading to pain from a bone-against-bone situation. Retired NFL players have a much higher prevalence of arthritis than the general population (41%-62% of players vs 9%-32% of US men). There are ways to determine if soreness is functional vs arthritic, but no media reports have provided any info to help me make a guess, so I'm unwilling to commit. If Urlacher continues to complain about soreness throughout this season and into the next, I would be more willing to consider arthritis as an underlying cause. That would mean the beginning of the end of his career, as the changes introduced by arthritis are irreversible, and Urlacher's continued play would be solely dictated by his pain tolerance.
There isn't much evidence of increased risk of arthritis after a knee sprain, especially since it was treated nonsurgically. Instead, arthritis is typically associated with fractures. There are some studies that show a higher risk if proper rehab isn't done and the joint remains unstable because the muscles aren't brought back to original strength. If there's anyone who takes his rehab seriously, however, it's Urlacher. I have no worries about this particular injury shortening his career.
This FanPost is long enough, so for those of you who are thinking tl;dr, here's a quick summary of my best guess at what's going on with Urlacher:
1) Urlacher likely suffered a grade III sprain (complete tear) of his MCL and a grade I or II sprain (partial tear) of his PCL from a large valgus stress on his left knee. He was lucky to have avoided worse.
2) Initial immobilization after injury caused his quad to weaken. He is still working on recovering and improving full strength in his quad. Until his quad reaches full strength, he is losing some dynamic stability of his knee, leading to functional soreness.
3) He is using a hinged, functional knee brace, the first brace he's ever used in his life. This alters the dynamics of his knee, which takes time for his muscles to get used to, leading to functional soreness.
4) There are no reports of scoping or needing a new MRI, both of which are used to probe structural issues, like reinjury or excessive scarring. Therefore, his soreness is not likely to be structural.
5) Soreness may also indicate inflammation. Over the next few years, if he cannot control this inflammation, arthritic degenerative changes will affect his knee and lead to impaired function.
Urlacher has a passion for the game and a passion for our Bears. He's a vet who gains little from practicing in a defensive scheme he's mastered years ago. All of you should now have a better idea of his injury and his rehab, and hopefully that provides a little relief. I believe that we're in for a monster season, and that Urlacher is ready for a monster season himself.