Trunk and Hip Biomechanics Influence Anterior Cruciate Loading Mechanisms in Physically Active Participants

In the coming August issue of the American Journal of Sports Medicine, there is a great research study published called Trunk and Hip Biomechanics Influence Anterior Cruciate Loading Mechanisms in Physically Active Participants.  This study should be read by anyone who works with athletes, treats athletes or is an athlete.  This is often one of the most misunderstood and areas of the body that receives the least amount of attention and research.  We know from previous studies that improvement in proprioception of the core leads to improved athletic performance and decreases in athletic injury.  We know that fatigue greatly impacts proprioception and yet, forget about the contribution this has to the core.  So often, we become so centered or focused on the limb itself that is involved in the injury that we forget the foundational base that the limb is attached to.  That without this base, the limb has nothing solid to pull or contract from.  Considering, the authors of this study should be applauded for bringing this to light.

For years, the Dynamic Movement Assessment™ has aggressively assessed both single limb stability at the lumbopelvic region and core stability.  Yet so many times the Dynamic Movement Assessment™ has been questioned on the validity of and how that correlates to injury prevention and performance enhancement.  In our current and on-going research, we have shown that the most significant area impacted when comparing pre and post fatigue status has been on both of these areas, the core and lumbopelvic region.  With an abundance of research out there indicating the impact that fatigue has on injury rates and performance, with the Dynamic Movement Assessment™, we wanted to see exactly where that impact was originating from.  This research further highlights the importance of.

Research has indicated that excessive trunk motion (rotation or side bending) and deficits of the lumbopelvic region complex are risk factors for ACL injury.  However, the relationship between these three has not been examined or determined during side step cutting tasks.  So the authors of this study analyzed the hip and knee biomechanics and trunk motion of 30 participants during side step cutting tasks.  Ground reaction forces were also determined during the first 50% of the stance time during cutting tasks. 

What the authors found was there greater knee varus moment associated with decrease in transverse plane trunk rotation away from the stance limb and greater internal rotation.  There was also found greater internal knee external rotation moment associated with greater trunk flexion and greater hip internal rotation.  So, what does that mean?  This means having trunk rotation toward the new direction of travel with decreased truck flexion results in decreased internal rotation and valgus stress (mechanism of ACL rupture) than if you have greater truck flexion and rotation or side bending.  This is vitally important because it highlights the importance of not just the strength, but also the proprioception of the lumbar spine, lumbopelvic region as well as the hip.  If those foundational components (strength and proprioception) are not present in those areas, then the athlete is a greater risk.  We also know that endurance plays a crucial role in both these foundational components which also must be considered in assessment.  Yet, how do we assess that?

This is an article about research and we don’t want to make it about the Dynamic Movement Assessment™.  That said, articles like this further validate the methodology behind such a movement assessment.  One that is physically challenging, which assesses both core and the lumbopelvic region in single limb stance and which has a fatigue component to assess true performance during athletic activities and not just during an isolated movement.  Whether you use an assessment tool like this or not, articles such as this should give us pause to consider all aspects of what we should assess when assessing athletes.

About the author:  Trent Nessler, PT, DPT, MPT.  Trent is a practicing physical therapist with 14 years in sports medicine and orthopedics.  He has a bachelors in exercise physiology, masters in physical therapy and doctorate in physical therapy with focus in biomechanics and motor learning.  He author of a textbook “Dynamic Movement Assessment™: Prevent Injury and Enhance Performance”, is associate editor of the International Journal of Athletic Therapy and Training, Member of the USA Cheer Safety Council and founder/developer of the Dynamic Movement Assessment™.

Reference:

1.      Frank B, Bell D, Norcross M, Blackburn J, Goerger B, Padua D.  Trunk and Hip Biomechanics Influence Anterior Cruciate Loading Mechanisms in Physically Active Participants.  Am J Sports Med.  July 2013 Preview.

2.      Brophy R, Schmitz L, Wright R, Dunn W, Parker R, Andrish J, McCarty E, Spindler K.  Return to Play and Future ACL Injury Risk After ACL Reconstruction in Soccer Athletes From a Multicenter Orthopaedic Outcomes Network (MOON) Group.  Am j sports med.  40:2517-2522, 2012.

3.      Holm I, Oiestad B, Risberg M, Gunderson R, Aune A.  No Difference in Prevalence of Osteoarthritis or Function After Open Versus Endoscopic Technique for Anterior Cruciate Ligament Reconstruction: 12 Year Follow-up Report of Randomized Controlled Trial.  Am j sports med.  40:2492-2498, 2012

4.      McCullough K, Phelps K, Spindler K, Matava M, Dunn W, Parker R, Reinke E.  Return to High School – and College-Level Football After Anterior Cruciate Ligament Reconstruction: A Multicenter Orthopaedic Outcomes Network (MOON) Cohort Study.  Am j sports med.  40:2523-2529, 2012