It's hard to believe that it is 2014.  The spring semester is now in full swing, as we are completing our second week of classes.  I am teaching anatomical kinesiology, sport biomechanics, and motor learning this semester.  So far things are going well, and I am looking forward to a good semester.  I am taking a group of students to the Southeastern Chapter of the American College of Sports Medicine annual meeting and symposium in February, and I will do a blog post about the trip.

The winter Olympics start in about 2 weeks, and I am definitely looking forward to that.  I am planning on doing a series of blog posts about the biomechanics of selected winter Olympic sports, similar to what I did with the 2012 London Olympics.  I do not know as much about winter sports, so it will definitely be more of a challenge, but one I am looking forward too.

It is also hard to believe that Cameron will be 3 years old in March.  He has grown up so fast, and is so much fun.  He is really smart and loves to read books and do puzzles.  He is also becoming pretty proficient in his anatomy knowledge, as he can say and identify his clavicle, patella, femur, tibia, scapula, and calcaneus.  It is never too early to start learning anatomy.  I also enjoy teaching the motor learning class as I watch Cameron learn how to perform new motor skills.  It has definitely given me a new perspective on that class.

More on the ALL ligament

Last week, I wrote about the discovery of a new ligament in the knee, the Anterolateral ligament (ALL).  This week I'm going to share my opinion on the ligament.  The first thing I thought when I read this, was "how did they just now discover this ligament?"  Doctors and scientists have been examining the human body, especially cadavers, for hundreds of years.  How could they just now discover a new ligament in the knee?  I'm not sure exactly what the answer to this question is.  Back in the late 1800s there was mention of this ligament, but nothing else came about until recently.  It could be that the location of the ligament made it difficult to find when examining the knee, or maybe it was mistaken for another structure.

Another important question is what is the clinical implication of this ligament?  Since it is on the anterior and lateral part of the knee, it would play a role in stabilizing the knee against anterior shear force.  An excessive amount of anterior shear force is a main mechanism for an ACL tear.  The ALL ligament might also be torn by this mechanism of injury, and since doctor's weren't aware of it's existence, it was not being repaired along with the ACL.  Thus, a person who sustained a tear of both the ACL and the ALL was only having one of the ligaments repaired, and therefore their knee was still somewhat unstable after surgery.  This is just a hypothesis, and much research and testing needs to be conducted to determine the exact clinical significance of the ALL ligament.

New Knee Ligament Discovery

Last month, surgeons in Belgium announced the discovery of a new knee ligament.  They are calling it the anterolateral ligament (ALL), and it is located on the anterior (front) and lateral (outside) part of the knee.  A French doctor in 1879 was the first to propose that there might be an additional ligament in the knee.  As you can see in the picture above, the ALL ligament starts in the same place as the LCL (lateral collateral ligament) on the lateral side of the femur, but it then runs more anteriorly and attaches to the tibia, where the LCL attaches to the fibula.  There are some questions surrounding the discovery, mainly, why did it take so long for this ligament to be found, and what does the ligament do?  Some people are even skeptical of the existence of the ligament.  I'll write again next week about my opinion of the ligament and what function it might serve.  This is a potentially big finding that may have implications for the future of knee surgery.

Fractured Clavicle

If you watched Monday Night Football, then you saw Green Bay Packers quarterback Aaron Rodgers leave the game after being hit and landing on his left elbow and shoulder (below).  The force from the ground (ground reaction force) caused Rodgers' clavicle (collarbone) to break.  With this mechanism of injury, the athlete will typically sustain either a clavicular fracture or a sprain of the acromioclavicular (where the clavicle articulates with the scapula) joint.  When Sam Bradford was playing college football at Oklahoma, he sustained two acromioclavicular joint sprains of his left shoulder with a similar mechanism as the one that injured Rodgers.  A fractured clavicle "normally" takes about 4-6 weeks to heal, but it could be faster or slower depending on the athlete and the type of fracture.  The athlete still has to be able to perform all the necessary movements before he or she is required to play.  The good news for Rodgers is that he broke the clavicle of his non-throwing shoulder, but this will still restrict his ability to throw a football while the injury heals.  He will likely miss at least 4 weeks of action, although it could be up to twice as long.

Unloading Reaction

We have been discussing in neural control the role of reflexes in the control of voluntary movement.  Yesterday we discussed a hypothesis that believes that reflexes play a very minor role in movement, and the central, voluntary commands sent from the brain control almost all aspects of voluntary movement.  There is a pretty cool reflex known as the unloading reaction that disproves this theory.

Imagine that you are holding a dumbbell in your right hand, and you are attempting to keep your elbow flexed (bent) at about 90 degrees.  You are instructed to continuously try and contract the elbow flexors (think biceps brachii, brachialis) in order to maintain this position, and you are instructed to continue to try and activate the muscles no matter what happens.  As you are holding the dumbbell, it is quickly removed from your hand.  What happens to the activity of the elbow flexors?

When the dumbbell is removed from your hand, there is a period of almost complete silence (no activity) in the elbow flexors.  Why does this occur even when you are trying to activate the elbow flexors?  When the dumbbell is in your hand, it activates the muscle spindles in the biceps (the dumbbell is trying to lengthen the biceps, which activates the muscle spindles), which causes a reflexive contraction of the biceps.  When the dumbbell is removed from your hand, muscle spindles are no longer activated, so there is no reflexive contraction of the elbow flexors.  This demonstrates that reflexes play more than a minor role in the control of voluntary movement.

Disturbing, but not surprising news

A recent report in the Chronicle of Higher Education talks about the difficulty that many athletic trainers face in dealing with injuries, particularly concussions, because they either report directly to the head coach or feel pressure from the coaching staff to return an athlete to play before he is ready.  I'm not going to comment extensively on this, but you can read another opinion here, and this link contains a good animation of the problem.  For full disclosure, I worked for one of the athletic trainers quoted in the first article when I was at Auburn.  There is definitely a clear conflict of interest between an athletic trainer and a head coach, especially in the ultra competitive world of NCAA football.  Most coaches have the best interest of the athletes in mind, but during the middle of a game, they cannot objectively decide if a player is able to return to a game, nor  are they trained to make this decision.  A head coach should also not evaluate the the skills of a medical professional.  Except for a few high schools games I covered, I never had to make the ultimate decision about rather or not a player can return to a game (that responsibility ultimately should rest with the team physician), but I can attest that the times I had to tell an assistant coach that one of their position players could not return to a game was not enjoyable.  Hopefully this report will open some eyes and lead to positive changes. 

New rules are going to lead to more injuries?

I blogged last week about the new rules in the NFL and NCAA that are targeted at preventing football players from hitting their opponent in the head or leading with their head when making a tackle.  The purpose of these rules is to cut down on the number of head and neck injuries.  I've heard some commentary recently on ESPN from former players saying that these rules will cause an increase in the number of knee injuries.  They think because defenders cannot tackle offensive players by hitting them in the head, they will now target their knees, because they don't have any other option.  Now, I didn't play football, or coach football, but it seems to me like there are a lot of other options besides hitting a player in the knees or the head.  I know when I was working as an athletic trainer with the football teams at Southern Miss and Auburn the players were not taught to tackle by hitting in the head or knees.  They were taught to hit a player in the chest or middle of the body and then wrap them up.  I think there are other options for tackling besides the head and the knees.  It may take some adjustments, but I don't think these new rules should cause a huge spike in the number of knee injuries.