Monday, March 25, 2019

Impact of Concussion on Single Limb Stability: Part III

Last week, we looked at a recent study Johnson et al Am J Sports Med 2018This study looked at dynamic balance following a sports related concussion to assess the movement of the COM during dynamic testing in those who have been previously concussed and those who have not.

As a review, this study looked at male rugby players who received a baseline test in dynamic balance while wearing an inertial measurement unit (IMU).  They then looked at those who had a previous concussion, those that suffered a concussion during the season and compared that to those who did not.  One of the things the investigators found was those players who went on to sustain a concussion had statistically significant difference in dynamic stability when compared to who did not sustain a concussion.

This is very interesting and confirms some of the trends we are seeing in our data.  For one, we see athletes who have had a concussion have a larger center of mass (COM) displacement, greater loss of pelvic control and higher magnitude and speed of motion in the frontal plane during single limb performance.  Ironically, we are also seeing that athletes who improve their performance on these measures are LESS likely to suffer a concussion.  In one of our most dramatic cases where we have seen this is in a project that we did with Division I football.  This has been submitted for publication but to give a preview, in this study we implemented the ViPerform AMI with all the athletes (109) and based on their results, we assigned them to the ACL Play It Safe Program (level I-IV).  We did this for 2 years and tracked the results over those two years.

What we saw was, not only an improvement in their baseline ViPerform AMI scores, but also a 44% reduction in concussions over the course of the two years we performed the study.  I think this leads us all to the same question, what is the mechanism behind this?  Frankly, we do not know what that answer is.  However, we are seeing this trend repeat itself over and over again in all the studies we are performing.  Keep in mind what it is we are doing.  We are tracking core stability and frontal plane stability in single limb performance.  We are then putting them on a program to specifically addresses the biomechanical flaws that we see.  Keeping in mind there is a large emphasis on single limb performance and core stability.

What we know, from previous studies and our experience, is that when you improve these factors (core stability and single limb performance) this has a direct impact on athletic performance.  Specific measures we look at are vertical jump and sprint speed.  So we know that power output improves and we would suspect that agility also improves.  So, if we are having an impact on an athlete's agility, are we impacting their ability to avoid a concussive event?  We don't know that answer but it does make sense considering all the other evidence that we have.

No matter what the case, if we look at the current evidence, we know athletes are at greater risk of knee injury post concussion (up to 2 years post concussion - Gilbert et al Am J Sport Med 2016).  If you also consider some of the trends we see (increase COM displacement, increase frontal plane motion and loss of balance), it would make sense that we should include this type of training as a part of our post concussion rehabilitation.  This is one reason we have included the ACL Play It Safe as a part of our post concussion protocol.  If this is used as a part of the post concussive protocol, then should we not use this as a part of our approach to reducing the risk for concussion?

If we look at the trend in injury prevention (ACL specific), what we see is trend to take some of the late phase rehab protocols and carry those through as a part of the in season injury prevention protocols.  If that is the case with our throwing shoulder prevention programs, our ACL prevention programs or our low back pain prevention programs, why would we not want to do that with our concussion prevention programs.  Considering, what we may find, if we take this approach, is that we not only see a reduction in ACL injuries, we not only see a positive impact on athletic performance, but we also see an impact on concussion rates.

I realize this is a big leap for a lot of us but I hope, based on all the evidence presented, we can all begin to see this is a logical progression of where the research is leading us.  More importantly, it is along the same trends we are seeing in our data.  At a minimum, we help athlete's reduce risk for lower kinetic chain and improve their athletic performance.  If we reduce some concussions along the way, then all the better!

Next week, we will start our discussion on RTPlay.  Hot topic in sports medicine and where is the research leading us?  If you enjoy this blog, please share with your colleagues and follow us on instagram @ bjjpt_acl_guy and twitter at @acl_prevention.  #ViPerformAMI #ACLPlayItSafe

Dr. Nessler is a practicing physical therapist with over 20 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment and ACL injury prevention.  He is the founder | developer of the ViPerform AMI, the ACL Play It Safe Program, Run Safe Program and author of a college textbook on this subject.  Trent has performed >5000 athletic movement assessments in the US and abroad.  He serves as the National Director of Sports Medicine Innovation for Select Medical, is Vice Chairman of Medical Services for USA Obstacle Racing and movement consultant for numerous colleges and professional teams.  Trent has also been training and a competitive athlete in Brazilian Jiu Jitsu for 5 years. 

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