Monday, November 12, 2018

Limb Symmetry Index - What is it and Is it important - part III


Last week, as we continued our discussion on Limb Symmetry Index (LSI), we looked at the Wellsandt et al 2017 study which provided some insight as to how we might assess LSI in Anterior Cruciate Ligament Reconstructed (ACLR) athletes.  Traditionally this was done by comparison of the involved limb to the uninvolved limb at the same time (same time post op ACLR).  However, this study indicates that a more sensitive measure may be comparing the involved side post operatively to the non-involved side pre-operatively.  Measuring in this fashion would prevent any of the degradation that might occur to the uninvolved side as the result of lower level of activity due to surgery on the involved side.  In other words, it would prevent the detraining effects on the uninvolved side from influencing the LSI measure.

For the purposes of this study as well as in most instances, LSI is a common measure used to determine whether an athlete is ready for return to play.  However, there appears to be a lot of inconsistency in what is measured for return to play, specifically following ACLR.  So what types of measures should be used to determine LSI? So Melick et al Br J Sports Med 2016 performed a systematic review of the literature to determine what we should be assessing, according to the literature, when we are looking to return an athlete to play following an ACLR. 


Methods:
The authors of this study did a systematic review of studies published from 1990 to 2015.  Ninety studies were included that addressed 1 of 9 predetermined clinical topics.

1.     Preoperative predictors for postoperative outcomes
2.     Effectiveness of physical therapy
3.     Open and closed kinetic chain quadriceps exercises
4.     Strength and neuromuscular training
5.     Electrostimulation and electromyographic feedback
6.     Cryotherapy
7.     Measures of functional performance
8.     Return to play
9.     Risk for reinjury

Results: Rehabilitation after ACLR should include a prehabilitation phase and 3 criterion based posteroperative phases:

1.     Impairment based
2.     Sport specific training
3.     Return to play

A battery of strength and hop tests, quality of movement and psychological tests should be used to guide progression from one stage to the next.  Post-operative rehabilitation should continue 9-12 months.  To assess readiness to return to play and the risk of reinjury, a test battery including strength tests, hop tests, and measurement of quality should be used.

Discussion: This study brings up a lot of good information but also brings to the forefront some important questions.  First, as a sports physical therapist, the blaring question is around the 9-12 months of rehabilitation.  Although I could not agree more and studies are pretty clear that athletes should not return to play for 12 months, how do we get insurance to pay for this?  With changes in health care and insurance reimbursement, the majority of insurance companies limit your care to 4-5 months post operatively.  None will pay for rehabilitation that includes return to play.  This despite the fact that reinjury rates are so high, osteoarthritis rates are so high and the majority of athletes who have will return to play whether or not they get the appropriate course of care.  Considering, I think we must be more creative in our plan of care and more inclusive of collaborative partners in the entire continuum of care for our athletes.  By early inclusion of our athletic trainers and strength coaches in the process not only allows us to have a more well-rounded approach to the athlete, it is also in the best interest of the athlete’s long term joint health and overall health to have this approach.  At the same time, we must include innovative ways to continue the athlete’s progression without our immediate and constant direction.  Programs like the ACL Play It Safe program provide us structured ways to progress an athlete through the process in addition to what our athletic training and strength coach counterparts would do. 

 Another point this brings up is what tests should we use to return an athlete to play?  When reviewing the literature, there does not appear to be a lot of consistency in how this is assessed.  Some studies look at variance in quadriceps strength, some in single leg hop distance, single leg triple hop distance, LESS test, timed hop, agility drills, the list is endless.  So what is right?  

 Next week, we will start to look at this question in a little more depth.  So make sure to stay tuned.  If you enjoy this blog, please share and follow us on instagram @ bjjpt_acl_guy and on twitter @ 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 is also a competitive athlete in Brazilian Jiu Jitsu. 



Monday, November 5, 2018

Limb Symmetry Index - What is it and Is it important - Part II

Last week we started our discussion about limb symmetry index (LSI) and specifically related to the lower kinetic chain.  We also know this is a measure that is commonly used by physicians and in sports medicine when making return to play decisions.  Based on some of the information provided last week, we have questioned on whether this is truly providing us a measure of risk, especially when looking at return to play.  Last week, we discussed a study by Rohman et al that looked at changes in LSI with ACLR rehabilitation but then also discussed the Adams et al study which showed that 93% of normal uninjured athletes LSI index was below or at the standard currently being used to determine return to play. 

This week, we will look at another study by Wellsandt et al J Ortho Sports Phys Ther 2017 which dives into this subject a little deeper.  The objective of this particular study was to evaluate LSI in return to sport testing and its relation to reinjury rates after ACLR.

Methods: Seventy athletes completed quadriceps strength and 4 single leg hop tests before ACLR and 6 months after ACLR.  LSI for each test compared to the involved limb measures at 6 months to uninvolved measures at 6 months.  Estimated preinjury capacity (EPIC) levels for each test compared the involved limb measures at 6 months to uninvolved limb measures before ACLR.  Reinjury rates were tracked for a minimum of 2 years post ACLR.

Results: Forty (57%) of patients achieved 90% LSI for quadriceps strength and on all hop tests.  20 patients (28.6%) met 90% EPIC levels for quadriceps strength and all hop tests.  Twenty four patients (34%) who achieved 90% LSI for all measures at 6 months after ACLR did not achieve 90% EPIC levels.  11 patients (27%) sustained a 2nd ACL injury at 78 weeks (median time).  8 of the 11 patients (73%) with the 2nd ACL injury passed with 90% LSI at 6 months.  But 6 of these 8 (75%) did not achieve 90% EPIC levels.  EPIC levels was superior at predicting 2nd ACL injury.

Despite previous studies stating there is little to no degradation of the noninvolved limb post ACLR, EPIC levels might indicate the contrary.  In this study, the most sensitive measure appears to be comparing the involved limb post ACLR numbers to pre-operative uninvolved numbers.  From a rehabilitation standpoint, if we can get pre-operative numbers, it would make sense to use EPIC levels when trying to determine return to play. 

That being said, it also leads us to the question, wouldn't it be even better if we had baseline movement data to compare to.  What if we had pre-participation movement data taken in physicals, would this be even more sensitive data to compare to.  For those of us that treat athletes who have had an ACLR, we know right after the injury the athlete is definitely going to be hesitant with movement.  Especially with hopping types of motions for the fear of landing on the involved injured limb.  So, would it be better to compare this to movement where there is not that hesitation at all?

All that said, are these LSI measures (whether done in traditional LSI measurement calculation or EPIC calculations) really providing information about "movement quality".  If the athlete had horrible movement prior to surgery on both legs, are we truly measuring risk?  When looking at the athlete depicted here, if this is the preoperative test on the uninvolved side, does his LSI or even his EPIC levels truly depict his risk for reinjury?  Are we missing something here or are we not using enough measures to measure this correctly?

Next week, we will look at some of the common battery of tests used for testing LSI and what they are telling us.  So make sure to stay tuned.  If you enjoy this blog, please share and follow us on instagram @ bjjpt_acl_guy and on twitter @ 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 is also a competitive athlete in Brazilian Jiu Jitsu. 

Monday, October 29, 2018

Limb Symmetry Index - What is it and Is It Important

Over the course of the last 5-10 years, there has been a lot of discussion in the literature about limb symmetry index or LSI.  So, what is LSI and what does it mean?  LSI or limb symmetry index is simply the variance between one limb (typically the involved or injured limb) and the other (uninvolved) limb.  This is usually represented as a % of the involved to the uninvolved (LSI = score involved/score uninvolved x 100).  LSI can be used to describe the variance between upper extremities or lower extremities.  However, most of the research done in this area is in relation to the lower extremity.  LSI is often used by physicians as one of the factors that is considered when determining an athletes ability to return to play. 

When looking at LSI for return to play, most physicians will tend to default to the conservative and shoot for an LSI of 90% to 95%.  The thought process here is that if there is greater than a 5-10% variance then this will put the athlete at greater risk.  Limb symmetry IS very important but, is this an accurate assumption?  And whether it is or not, how are we measuring LSI and is this truly an accurate measure of risk?  Let's first look at what does the research tell us about normative values for LSI.

In a study by Rohman et al Am J Sports Med 2015, the authors did a retrospective case series looking at LSI. 

Methods: Retrospective case series of 122 patients who underwent ACL reconstruction and rehabilitation.  Each subject received standard functional testing at 4 and 6 months post operatively.  The standard functional test (SFT) consisted of 12 exercises performed in the following order:

  • Single leg anterolateral reach - Patient balances upright on the tested leg only, and reaches with the contralateral hand as far as possible along the floor, at a 45 degree angle anterolaterally. (I.e., standing on the right leg, the patient reaches with the left hand forward and to their right). The patient is not allowed to bear weight on the reaching arm.
  • Single leg anteromedial reach -  Patient balances upright on the tested leg only, and reaches with the contralateral hand as far as possible along the floor, at a 45 degree angle anteromedially. (I.e., standing on the right leg, the patient reaches with the left hand forward and to their left). The patient is not allowed to bear weight on the reaching arm
  • Stork stance with eyes open - Patient stands on the tested leg with arms crossed over chest, and must maintain their balance without using arms for balance or touching down with the opposite leg. The trial ends at 60 seconds unless the patient loses balance sooner.
  • Stork stance with eyes closed - If patient is able to complete 60 seconds with eyes open, the test is repeated with eyes closed.
  • Retro step up - The patient steps backwards with the tested leg onto a raised platform, and straightens to an upright position without pushing off with the front (untested) leg. The patient then must then reverse this motion, performing a controlled descent bringing the untested leg back down to the floor. This is repeated with platforms of increasing size until the patient cannot complete the step up. 3 trials allowed at each height.
  • Single leg squat - Patient is standing on the tested leg without any support, and squats as deep as possible. Arms can be extended for balance. The opposite leg is not allowed to touch the floor or brace against the tested leg.
  • Single leg hop - Patient begins standing on the tested leg only, and hops forward as far as possible. Patient must demonstrate a balanced and controlled landing, without touching the untested leg to the ground for support.
  • Single leg triple hop - Patient starts balanced on the tested leg, and takes 3 consecutive hops forward on the tested leg only. Patient must demonstrate balanced and controlled landings, without touching the untested leg to the ground for support.
  • Cross over triple hop - Patient starts standing on the tested leg only. The patient then takes 3 consecutive hops forward parallel to a line of tape placed on the floor. Each hop must land only on the tested leg, and must land on alternating sides of the line of tape. Patient must demonstrate balanced and controlled landings, without touching the untested leg to the ground for support.
  • Timed hop - The patient starts balanced on the tested leg, and hops forward on that leg only as quickly as possible, over a distance of 6 meters. Patient must demonstrate balanced and controlled landings, without touching the untested leg to the ground for support.
  • Core plank - Patient is positioned prone on their elbows and toes, with a neutral spine. They must then hold this position for 60 seconds. The test ends if patient gives up, or displays excessive arching/sagging through the lumbar spine.
  • Single leg bridge - Patient is positioned supine with knees bent. They then straighten and elevate the untested leg, and with the tested leg extend through the hip, pushing down and lifting their core off of the ground until the hips are neutral. The patient is not allowed to touch the ground with the untested leg or brace against the tested leg.
The SFTs were performed at 4 and 6 months post operatively for both the involved and uninvolved leg.  Ten of the twelve SFTs were analyzed and compared for changes in LSI and absolute function in each limb.  

Results: In all patients with multiple SFTs, the involved limb performance increased in all tests with the exception of the stork stance with eyes closed.  Univolved limb performance increased in 5 SFTs and decreased in none.  5 tests showed initial LSI below 90% (single leg squat, retro-step up, single leg hop, cross over triple hop and timed hop.   

Conclusion:  During ACLR rehabilitation, the improvements seen in LSI indicated absolute increases and were not attributed to univolved limb deterioration.  The single leg squat, retro step up, single leg hop, crossover triple hop and timed hop are suggested as highly useful tests since showed initial LSI below 90% and had significant improvement with rehabilitation.  


So this study shows us that there are some good measures of LSI, but are they really telling us you are at risk and are we being too stringent on the thresholds?  Meaning is this 90%-95% LSI too restrictive and more importantly, does 95% or 100% LSI mean you are not at risk? 

In a study by Adams et al J Ortho Sports Phys Ther 2012 the authors showed that 93% of normal individuals (those without injury) had an LSI of 85% or greater.  So I ask again, is the current threshold of 90-95% too restrictive and if you don't meet that threshold, are you really at risk?

As we have seen over and over again, you can have 100% LSI of really bad movement.  I think we could all look at this athlete and despite having 100% LSI, we would agree she is at risk.  So, are we relying too much on LSI and what is it really telling us?  We will continue to dive into this question again next week. 




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 is also a competitive athlete in Brazilian Jiu Jitsu. 


Monday, October 22, 2018

How Does Human Movement Occur - Kinetic Chain in Action - Part III


Last week we ended our discussion looking at how poor posturing loads various portions of the body.  We will continue to see how this posturing impacts thoracic spine on down to the foot.


Thoracic scoliosisKeener JD, Brophy RH. Superior labral tears of the shoulder: pathogenesis, evaluation, and treatment. J Am Acad Orthop Surg. Oct 2009;17(10):627-37.

·       Causative factors – because baseball and especially pitching is an asymmetrical sport, pitchers tend to over develop on one side and under develop on the other side as noted earlier.  In the thoracic spine, this results in increased muscle tension on one side of the spine and decreased muscle tension on the contralateral side.  Since the spine is a mobile structure, this can result in the bending toward the stronger side or the side with increased tension.  This will present as scoliosis.  It should also be mentioned that baseball, especially professional baseball, tends to attract demographics and recruit internationally from regions which tend to have higher incidences of scoliosis.  So, although scoliosis in the example may be associated with the factors mentioned above, this can also be associated with genetic factors as well.


·       Potential injuries – with thoracic scoliosis, because of the abnormal position of the spine there is also abnormal loading of the spine.  The human spine is meant to be loaded in an 80/20 relationship where 80% of the weight is absorbed through the bone disc bone interface and 20% of the weight is absorbed through the facet joints.  Abnormal spine positioning of the spine alters this loading relationship.  This can add to accelerated breakdown of tissues and pain in the joints, ligaments or muscles of the thoracic spine.  Curvature in the frontal plane also adds to distraction of the costalvetebral joints on the concave side and compression on the convex side.  This can add to costalvetebral pain as well as increase the potential for costalvetebral subluxations.


·       Performance issues – with a change in position of the spine, there is also a significant change in the length tension relationships of the musculature that attaches at various portions of the spine.  With curvature in the frontal plane, muscles are lengthened and shortened on the convex and concave side.  These altered length tension relationships add to imbalances in strength along the spine and the lower extremities.  This not only impacts transfer of kinetic energy but also then power output.  In instances where there is pain, this results in even further weakness of the spinal extensors, which if not addressed can lead to loss of up to 25% of the cross sectional area of the muscle (Hides et al, Spine, 1996).[i]   In the pitcher example, this can cause increased fatigue in the thoracic spine earlier in the game which puts increased demands on the shoulder and scapula stabilizers.  If they are also weakened, this accentuates the impact on overall performance, pitching velocity and pitching tolerance or endurance.

Pelvic asymmetry

·       Causative factors – in a closed kinetic chain situation, positioning of one end of the chain impacts positioning on the other end.  In the spine and pelvis, this is especially true since the two are connected via the sacroiliac joint (SI).  Therefore, one cause of pelvic asymmetry can be scoliosis.  However, if there is a pelvic asymmetry, this will also cause curvature of the lumbar and thoracic spine in the frontal plane.  So, does pelvic asymmetry cause curvature of the spine in the frontal plane or does curvature in the frontal plane cause the pelvic asymmetry?  This is an important question to answer during a differential diagnosis.  Another factor that can lead to a pelvic asymmetry is a leg length discrepancy.  Although a “true” leg length discrepancy is rare and usually the result of genetic factors (hemihypertrophy), tumors (hemangioma - blood vessel tumor or Wilm’s tumor – tumor of kidney causing hypertrophy of the limb) or epiphyseal issues (injuries or infections in the growth plate), these are typically not diagnosed during a visual examination alone and require further testing to uncover.  An “apparent” leg length discrepancy, though, can be assessed during visual and musculoskeletal evaluation.  There can be a plethora of causative factors, including lumbar spine and core weakness or tightness, pelvic weakness or excessive flexibility (common in women who carry a child on a single hip predominantly) or excessive foot pronation.


·       Potential injuries – with pelvic asymmetry, many tissues and structures are abnormally loaded.  In reviewing just the most proximal and distal structures, one could expect to see abnormal loading of the lumbar spine, the sacroiliac (SI) joint, the hip joint, trochanteric bursa and the iliotibial band.  The lumbar spine is placed in a more side bending position with pelvic asymmetry, and therefore there is increased potential for low back pain.  There is increased shear stress in the SI joint which can contribute to pain.  At the hip, there is increased compression of the femoral head in the acetabulum which may contribute to hip labral tears, wearing of articular cartilage and pain.  On the side of the hip, where the ilium appears to be elevated, there is increased tension on the iliotibial band.  This can add to increased incidence of trochanteric bursitis and IT band friction syndrome.    

·       Performance issues – besides the indirect impact the asymmetry would have on performance as a result of potential pain issues, pelvic asymmetry also can have a more direct impact on performance as well.  As a result of the frontal plane motion that occurs during gait and sport related activities, when there is pelvic asymmetry there can be marked decrease in endurance of the hip, core and lower extremity.  Endurance and overall power output are also affected because of the change in the length tension relationships of the musculature of the lower extremity, hip and core.  In the example of the pitcher, pelvic asymmetry can result in increased fatigue in the lumbar spine, hips and lower extremity which places increased demands on the upper body to maintain velocity or power output.  The impact on overall performance, pitching velocity and pitching tolerance or endurance is compounded if there are weaknesses and poor postural alignments higher up the kinetic chain.


Foot Asymmetry


·       Causative factors – because the foot is the first portion of the kinetic chain to impact or be in
contact with the ground, misalignment of the foot will have a dramatic impact on the alignment and loading of all of the proximal joints, including the ankle, knee, hip and lumbar spine.  Two common alignment issues that we see in a postural assessment are supination (in relation to position of the calcaneous) resulting in pes cavus (in relation to the position of the medial arch) of the foot and pronation resulting in pes plantus of the foot.   The position we most often observe in athletics however is calcaneal pronation resulting in pes plantus.  This may present bilaterally but in many cases will present with an asymmetrical pattern, meaning that it will be much more pronounced on one side versus the other or be present on one side and not present at all on the other.  In cases that present asymmetrically, we often see much greater dysfunction during sports performance and/or increased injury potential on the side with the most pronounced pronation.  This can result in the athlete being plagued with injuries along the kinetic chain on the side with the greatest magnitude of pronation.  When the calcaneous falls into excessive pronation in a closed kinetic chain the result is genu valgum at the knee, adduction at the hip and pelvic asymmetry.  Although many believe this is the “main cause” of pathokinematics, research has shown us that proximal weakness in the hip and core can also result in pronation and pes plantus at the foot and ankle.  In fact, pronation and pes plantus can be caused by a multitude of factors including weakness of the posterior tibialis, intrinsics of the foot on the plantar aspect, hypermobility of the plantar fascia or calcaneous, or proximal weakness in the hips and core.   


·       Potential injuries – with calcaneal pronation, many structures are loaded in an abnormal fashion.  In reviewing proximal and distal structures, one could expect to see abnormal loading of the medial arch of the foot, the retrocalcaneal bursa and Achilles tendon, the anterior tibialis, tibia (shins) and knee.  With the decreased arch, the foot becomes flat footed in full weight bearing (pes plantus) which increases potential for pain in the arch of the foot as well as the heel, and posterior heel.  With the loss of shock absorption with the fallen arch, this can place more work and strain on the anterior tibialis and the shins adding to anterior shin pain.  At the knee, there is a resultant genu valgum which increases the potential for strain on the cruciate ligaments and meniscal injuries.  Along with this positioning of the knee, there is alteration of the “normal” articulating pattern of the patella in the femoral groove which can lead to patellar tendonitis or patellofemoral syndrome. 


·       Performance issues -- besides the indirect impact the asymmetry would have on performance as a result of potential pain issues, pronation can also have a more direct impact on performance as well.  As a result of the large degree of motion that occurs during gait and sport related activities, when there is excessive calcaneal pronation there can be a marked decrease in endurance of the foot, ankle, lower leg, knee and hip.  Endurance and overall power output are also affected as a result of the abnormal positioning and alignment of the joints in the closed kinetic chain.  In an example of a basket ball player, vertical height may be compromised when attempting to achieve a jump shot.  With excessive pronation of the foot and accompanying genu valgum, the force the athlete is able to generate through the quads and hamstrings is affected and the transfer of that energy to the foot/ankle and ground is also compromised.  Therefore there is not only a decrease in the force that is generated but also a decrease in the energy transfer as it is crossing a less efficient system.    


So, we can tell a lot about an athlete’s potential for certain types of injury as well as potential performance issues and limitations he or she might face by looking at posture as seen in these examples.  Addressing deviations like these can reduce the potential for injury, improve efficiency of the entire system and lead to higher athletic performance.


As basic as it sounds, to truly change movement, we must change the way that we think.  And although it is not 100% data driven, it is 150% science driven.  And that is, assess it better.  Move better, feel better, perform better and last longer.  That simple!   

 If you are enjoying our blog, please share it and follow us on twitter @ACL_prevention and on Instagram at @Bjjpt_acl_guy 


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 is also a competitive athlete in Brazilian Jiu Jitsu. 

[i] Hides, Julie A. PhD; Richardson, Carolyn A. PhD; Jull, Gwendolen A. MPhty. Multifidus Muscle Recovery Is Not Automatic After Resolution of Acute, First-Episode Low Back Pain. Spine. 21(23):2763-2769,1996

Monday, October 15, 2018

How Does Human Movement Occur - Kinetic Chain in Action - Part II

Posture

Posture is an intentional or habitual assumed position.  The definition includes physical carriage, or the way one holds his or her body and body position, which refers to the various position(s) the body can assume.  Another way to look at posture is to think of the “arrangement of body parts,” or in other words, the way that the components of the body are aligned in relation to each other.

What does posture tell us that is important in our discussion of the kinetic chain and movement, specifically pathokinematic movement?  Posture can tell us a tremendous amount about symmetry, strength, tightness and the potential for injury in the body.  For our purposes here, we will define human posture, or the arrangement of the body and limbs, in terms of a static (fixed) position.  It is a motionless position or stance of natural comfort.  According to Kendall et al “in standard posture, the spine presents the normal curves and the bones of the lower extremities are in ideal alignment for weight bearing. The neutral position of the pelvis is conducive to good alignment of the abdomen and trunk, and that of the extremities below.  This aids in the optimal performance of the core as well as the lower extremities.”  Kendall et al, (1993) further state that “the chest and upper back are in a position that favors optimal function of the respiratory organs. The head is erect in a well balanced position that minimizes stress on the neck musculature.”[i]

In this “optimal position” the cartilage, joints, ligaments, muscles and tendons are loaded in the “optimal fashion” or placed in “correct” length tension relationships (the relationship between the length of the muscle and the force it can exert) and the overall efficiency of the system is maximized.  We will discuss this more in Chapter 5 when we look at pathokinematics and performance.

During work, school, exercise or training activities individuals can develop poor posture, meaning posture that is outside of this “optimal position.”  If poor posture is not corrected or addressed otherwise with training protocols, this can lead to what Janda, et al (1996) refer to as “Crossed Pelvic Syndrome.”  Janda describes this as occurring when there is:


§  Weakness or inhibition of the lower abdominals (or transverse abdominus)


§  Tightness of the hip flexors (iliopsoas) and gluteus maximus/lower lumbar spine[ii]


This not only impacts the potential for low back pain but can also have a dramatic impact on force production, strength and endurance of the entire kinetic chain.  Visually, these postural anomalies can be observed both from anterior and lateral views, although they are easiest to see from the lateral view.  Some postural anomalies we can observe from the lateral aspect include but are not limited to:


·       Forward head – increased extension of upper cervical spine and forward flexion of lower cervical upper thoracic spine

·       Rounded shoulder – protraction of the scapula

·       Increased lumbar lordosis – anterior pelvic tilt with butt tucked in and hips slightly forward

·       Increased genu recurvatum – hyperextension at the knee


Some postural abnormalities that we observe from the anterior or posterior aspect include but are not limited to:

·       Cervical sidebending – head is tilted to one side or the other

·       Shoulder depression – one shoulder appears lower than the other

·       Scapular tipping or winging – where the inferior border (tipping) or medial border (winging) is more prominent

·       Scoliosis –curvature of the spine

·       Pelvic asymmetry – one ileum or iliac crest appears higher than the other

·       Hip adduction – where the hip or femur appears to be more toward the midline

·       Genu valgum - knees touch, but ankles do not (knock-knee); or varum - outward curvature of one or both legs at the knee (bowleg)

·       Foot pronation - foot turns outward, ankle rolls toward center; or supination - foot turns inward, ankle rolls outward.


 

Certain postures, and particularly abnormalities in posture like those described above, can provide invaluable information about muscle tightness, muscle imbalances and potential injury and performance issues as noted earlier.  For example, if we are performing a visual examination of a college baseball pitcher, we may notice some deviations commonly seen in pitchers.  This would include but is not limited to:  scapular protraction and depression, scapular winging, thoracic and lumbar scoliosis, pelvic asymmetry, hip adduction, genu valgum and foot pronation.  For the college pitcher, this can be the result of years and years of participation in a sport that requires an asymmetrical or one-sided position.  If this asymmetry is not addressed with training both during the season and after, tightness and weakness can result that can lead to injury and decrease performance.  Let’s look at a few postural deviations more closely, reviewing the likely causes, potential injuries that can occur, and a few of the performance issues that can arise:

Shoulder depression/winging:

·       Causative factors – throwing is predominately an asymmetrical activity resulting in over development of some of the shoulder muscles on the throwing arm as well as underdevelopment of some of the muscles of the same shoulder.  With over development, the non-throwing arm appears underdeveloped in relation to the throwing arm.  Throwing results in tightness of anterior structures on the throwing arm which then in turn results in the scapula resting in a more
protracted and depressed position on the thoracic spine.  This can be the result of tightness of the anterior structures (pectorals, etc.) and weakness of the posterior structures (rhomboids, etc). 

The rhomboids originate on the spinous processes of the thoracic spine and insert on the medial border of the scapula from the scapular spine to the inferior border.  Collectively, they act to retract and downwardly rotate the scapula during upper extremity movement.  Winging is highly associated with weakness of the serratus anterior muscle.  The serratus anterior originates on the upper eight ribs and inserts along the entire anterior medial border of the scapula.  When the serratus anterior contracts, it depresses the medial border of the scapula against the thoracic cage, thereby aiding in the stability of the scapula during upper extremity movements and when the arm is elevated.  If this muscle is weak, then the scapula will wing through shoulder motion, and most predominately in the range from 90 to 120 degrees of shoulder flexion.  These positions are common for the shoulder during throwing motions or participation in over head sports. 

·       Potential injuries – with the scapula sitting in a more depressed and protracted position, there are several tissues that are compromised.  In this posture, there is a significant reduction in the subacromial space (space between the head of the humerus and the acromion).  Since this is the space that the supraspinatus and portions of the infraspinatus tendons pass through to their attachment on the greater tuberosity, a reduction of this space increases the potential for irritation and tears of the tendons, especially during overhead activities like throwing.  This position also results in compression of the anterior structures of the shoulder, specifically the long head of the biceps and the anterior labrum.  Both the long head of the biceps and the labrum are further compromised by the cocking phase of throwing.

·       Performance issues – with the distorted position of the scapula on the thoracic cage, the length tension relationships of many of the muscles associated with stability of the scapula as well as the rotator cuff are significantly altered.  If the scapula stabilizers and the rotator cuff are weakened, then the transfer of kinetic energy across the system will not be as efficient and there will be decreased power output.  This can lead to (in this case) a decrease in pitching velocity or a decrease in the ability to sustain velocity from one inning to the next.

Next week we will continue with looking at the Thoracic spine.  As basic as it sounds, to truly change movement, we must change the way that we think.  And although it is not 100% data driven, it is 150% science driven.  Over the course of the next month, I will continue to provide blogs to help us all understand better the sciences behind movement and why we should do what we should do.  And that is, assess it better.  Move better, feel better, perform better and last longer.  That simple!   
Next week, we will start to dissect this a little more.  If you are enjoying our blog, please share it and follow us on twitter @ACL_prevention and on Instagram at @Bjjpt_acl_guy 


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 is also a competitive athlete in Brazilian Jiu Jitsu. 

Monday, October 8, 2018

How Does Human Movement Occur - Kinetic Chain in Action

I went broke believing that the simple should be hard.
Matt Nathanson

In order to develop strategies which will improve movement, and eliminate pathokinematics in our athletes and others we work with, we must first understand how human movement occurs in the first place.  Our understanding of the human body and the systems that make it work, as vast as it is, is still so limited when it comes to its full and integral complexities.  For our purposes and the purposes of this blog, we mostly focus on the musculoskeletal system (skeletal system, muscles, cartilage, ligaments, tendons and joints), the nervous system (neuromuscular system - sensory and motor nerves and central nervous system – higher centers and spinal cord) and the cardiovascular system (heart, lungs, veins and arteries), and how they work together so that the body can move.   

However, the human body is an extraordinarily complex interaction of these and many other systems that influence its action, health and wellness.  The human body relies on the “optimal performance” of all of these systems in order to provide optimal performance in life and in sports.  If there is a break in any of the systems or “links in the chain,” then optimal performance cannot be obtained, and over time, damage can occur. 

The Kinetic Chain

Human movement occurs thanks to the “kinetic chain.”  Kinetic means force, and chain is defined as a system that is linked together.  Throughout this book, when we refer to the kinetic chain, we are referring to the system of interconnected body segments that allows the body to move.  For our purposes, the kinetic chain includes the parts of the body which directly or indirectly impact the positioning, alignment, strength, endurance and performance of proximal or distal segments of the body.  The nervous system, the musculoskeletal system, as well as the cardiovascular system, all work together to transfer energy or force through the body to the extremities in order to cause movement.  The majority of this text is focused on the lower kinetic chain, which for our purposes refers to all of the muscles, bones, ligaments, tendons, joints and all associated neurological input systems that influence those structures from the chest (pectoral muscles) to the feet. 

A kinetic chain can be open or closed.  A closed kinetic chain is one in which the hand or foot, or other moving body part, is in a fixed position during movement.  In this type of movement, because one or more extremity is stationary, resistance from the stationary surface is felt throughout the entire body, including and especially in the trunk, and specifically in the core.  In closed kinetic chain situations, when movement occurs all of the connected segments of the body are involved simultaneously.  An open kinetic chain is one in which the extremity or extremities are not fixed to any stationary surface and are therefore simply free in space.  In an open kinetic chain only the part of the body that is free in space and those parts closest to it are directly involved in the movement.

Therefore, in a closed kinetic chain, the parts of the system act in dynamic unison and in an open kinetic chain, they act more in isolated segments.  Most sports and functional life activities are closed kinetic chain activities, since in most cases the body or one of its extremities is fixed against a stationary object or surface (the ground, a chair, etc.) and all parts of the body work together dynamically.  Consequently, closed kinetic chain exercises require and reinforce recruitment patterns of the neurological, muscular and skeletal systems in ways that most closely mimic those used in sports and the activities of daily life.  They are the most effective for improving movement, preventing injury and enhancing sports performance, since they are more like sporting and “real life activities.”  Examples of exercises that are closed kinetic chain are squats and push-ups.  In comparison, leg extensions and triceps push-downs are examples of open kinetic chain exercises. 

How can we see the kinetic chain in action so that we can ultimately understand how movement occurs?  One way is to look the arrangement of the parts of the body by looking closely at the musculoskeletal system.  When we refer to the musculoskeletal system, we are referring primarily to the skeletal system, (bones), and the muscles, ligaments, tendons, other connective tissue and joints that hold the skeletal system in place.  We can see this system at work both when the body is still (statically) and when the body is in motion (dynamically).  Let’s begin by looking at the posture of an individual in a standing and stationary position.

As basic as it sounds, to truly change movement, we must change the way that we think.  And although it is not 100% data driven, it is 150% science driven.  Over the course of the next month, I blogs to help us all understand better the sciences behind movement and why we should do what we should do.  And that is, assess it better.  Move better, feel better, perform better and last longer.  That simple!   

Next week, we will start to dissect this a little more.  If you are enjoying our blog, please share it and follow us on twitter @ACL_prevention and on Instagram at @Bjjpt_acl_guy 


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 is also a competitive athlete in Brazilian Jiu Jitsu. 

Monday, October 1, 2018

How Will Your NFL Team Perform? - Know Their Injury Rates - Part III

Over the course of the last several weeks, we have discussed injury rates among NFL players and the impact this has on individual performance and overall team performance.  Obviously with such a high percentage of these being non-contact in orientation, prevention is the key.  You would think with the advent of technologies and advancements in movement, rehabilitation and performance sciences that we would have figured this out by now.  Apparently, we have not!

If you look at this list here, you can see we have a long way to go.  Pictured here are the players who have torn their ACL in the NFL as of 9.28.18.  Sadly, the number of ACLs that have occurred thus far are on trend to be representative of what has happened in the last 5 years.  If you look at this data, 29 of these occurred in preseason.  The remaining within the first couple of weeks of the season.  If you look at the mechanism of injury, you again see that >70% of these are non-contact in orientation.  The financial impact and the impact to individual and team performance has yet to be fully recognized.  Insanity - To do the same thing over and over and expect a different outcome!  Sadly, for the last 5 years, I have made this same statement.  How can we expect a different result if all we do is the same thing year over year. 

In our first section, we discussed what we should be assessing to determine risk.  Whether you are a NFL player, an elite athlete or a high school athlete, the literature is pretty clear that dynamic valgus is something we need to make sure to assess.  Yet, the majority of testing in the NFL uses assessments (movement screens) that have not been well validated in the research to be predictive of injury and which do not assess dynamic valgus.  In addition, many teams also use test which assess limb symmetry index.  Limb symmetry index (LSI) is the variance between your right leg and left leg during functional testing (single leg hop, single leg hop for distance, single leg triple hop).  Most of the research indicates if you have >15% variance then you are at greater risk for injury.  But, is that good enough?

It makes sense if you have a huge variance between the right side and the left side that you are at greater risk.  That would mean that you would always be putting more wear and tear on one side and the side that is weaker would be at greater risk because it is underdeveloped and may not be as resistance to the high forces associated with the sport when you are force to use it.  However, does an LSI of 100% mean you are at less risk?

Take the athlete depicted here.  In single limb testing, this athlete may present as 100% symmetrical.  But is that 100% of good movement?  I think we would all agree, this athlete is still at risk despite the fact that she is 100% symmetrical.  That is exactly what a study by Wellsandt et al in the 2017 Journal of Orthopedic & Sports Physical Therapy showed. 

Methods:
70 athletes completed quadriceps strength and 4 single leg hop tests before ACLR and 6 months after ACLR.  LSI for each test compared 6 month post op involved limb measures to involved 6 months post op measures.  Second ACL injuries were tracked for a minimum follow up of 2 years after ACLR.

Results:
57.1% (40) patients achieved 90% LSI for quadriceps strength and all single leg hop tests.  11 (15.7%) of patients sustained a 2nd ACL injury in the 2 year follow up period.  8 of the 11 patients with second ACL injury passed the 90% LSI return to sport criteria in quadriceps strength and single leg hop tests 6 months after the initial ACLR.

Discussion:
72.7% (8 of 11) of the patients who suffered a second ACL injury achieved 90% LSI.  Although that is only 20% (8 of the 40) of those who achieved 90% LSI, it begs the question on whether LSI should be the sole measure of return to play.  In many cases and as a standard of practice, this is often the case. 

So is the answer adding additional tests to capture true deficits?  Toole et al in the 2017 Journal of Orthopedic & Sport Physical Therapy looked at this in youth athletics.  What the authors found is when you add the recommended tests from the literature for RTPlay following ACLR reconstruction, you end up with:

  • IKDC - score 90 or better
  • 90% LSI on:
    • Quad/Ham strength
    • SL Hop
    • Triple Hop
    • Cross over hop
    • 6 meter timed test
In this study, the authors applied this criteria to 115 young athletes and found:
  • 13.9% met all the criteria
  • 43.5 to 78.3% met criteria on the individual tests

So, is it that our rehabilitation is not preparing people properly for functional testing and return to play or that we are not measuring the right things?  If we think back to part I of this discussion, we know we need to measure dynamic valgus and yet none of these tests are doing that.  So, do we continue to do the same thing and expect different results or do we try something different?

With the advent of wearable sensor technology we now have a way to accurately measure dynamic valgus.  Not only can we capture the magnitude of motion that occurs but also the speed at which it occurs.  Finally, we have a solution.  Once those at risk have been identified, we can now create programs to change those movements.  There are multiple programs out there that can efficiently impact these pathokinematics and improve the movements that put athletes at risk. 

Insanity - To do the same thing over and over and expect a different outcome.  Is it time for the insanity to be over or are we going to continue what we have always done and expect a different result?  I chose the former.  If you are enjoying our blog, please share it and follow us on twitter @ACL_prevention and on Instagram at @Bjjpt_acl_guy 


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 is also a competitive athlete in Brazilian Jiu Jitsu.