Over the course of the last
year, we have made several inferences about the impact that movement has on
tissue stress and bony alignment at the hip and suggested the impact this may
have on pathology in the athletic hip. All
to often in the medical sciences, we seek a peer reviewed research paper to guide
our critical thinking and clinical thought process. However, should we or could we use some of
the basics we were taught in anatomy and biomechanics to guide us? If we can, could this guide some of our
thought process in relation to hip pathology and movement assessment.
If we simply look at bony
anatomy of the hip alone (pictured here), we have the head of the femur and the
acetabulum of the pelvis. In an ideal
situation, the femur is centered at the intersection of the X in this
picture. With the femur positioned here,
we can see that a movement of pure adduction of the hip will bring the
intertrochanteric line in closer proximation to the anterior labrum. If adduction is combined with internal
rotation, then you bring the greater trochanter in closer proximation to the
anterior superior labrum. If you combine
these two motions with hip flexion, then this places these structures in even
closer proximation to the labrum.
It is the combination of
these motions that can result in femoral acetabular impingement (FAI) or hip
pain in the athlete. It is becoming fairly
well accepted that the combination of these motions is one of the driving
factors that leads to FAI, cam impingement, labral tears and anterior hip pain
in athletes. There is an increased number of papers as well
as orthopedic textbooks that describe these motions and the association with
this type of pathology. Due to the
higher loads associated with athletics, it is also one reason that we tend to
see this more commonly in the athletic individual. Despite the fact that these motions are being
more widely accepted as a cause and risk factor for developing FAI, rarely do
we assess this during movement for these types of pathologies. Typically, this is assessed during supine
examination and MRI. However, this begs
the question, can we assess this with movement?
Can we objectively quantify this during human movement in a meaningful
way for both preventative techniques and rehabilitation? More importantly, does supine testing
represent the true relationship between the acetabulum and femur in weight
bearing positions?
To answer that question, lets
look at a recent study published by Pullen et al in
the American Journal of Sports Medicine in 2014. In this study, the authors wanted to look at the
variability in acetabular coverage between supine and weightbearing.
Methods: 50 subjects 18 years or older who were referred for symptomatic
hips were evaluated for femoral acetabular impingement. Each of the subjects were evaluated using standardized supine and weightbearing anterioposterior pelvic radiographs. Measurements were obtained in each position
for acetabular coverage by two blinded reviewers for each of the 50 hips and
compared.
Results: Statistically significant differences between supine and
weightbearing radiographs were observed for all measurements of acetabular
coverage. Measurements of acetabular
coverage decreased between supine and weightbearing along with a considerable
increase in pelvic tilt noted with weightbearing position in 45% of the
subjects.
Discussion: Based on the above results, we see that acetabular
coverage is decreased when moving from supine to weightbearing positions. A decrease in acetabular coverage equates to
increased risk for FAI. In 45% of the
subjects, there was also a notable increase in pelvic tilt associated with
change in position from supine to weightbearing. Knowing that core strength and endurance is
vital to stability of the pelvis, this would indicate an increase demand on the
core for stability of the pelvis in weightbearing positions. It also points out the importance the core
plays in preventing excessive pelvic tilt and hence altered acetabular
coverage.
So, in going back to the
previous question, does supine testing represent the true relationship between
the acetabulum and femur in weight bearing positions or during sport, we know, based
on this study that answer would be no. So,
if acetabular coverage is not the same, then there is an alteration of not only
bony alignment but also length tension relationships of the entire lumbopelvic
complex. That said, should we look at
the previously mentioned movements (adduction, internal rotation and flexion) that
occur in the lower kinetic chain during weightbearing motions so we may identify
those at increased risk for FAI?
Stay tuned next week and we
will look at that further. We hope that you found this blog insightful
and useful. As we stated previously, stay tuned and if you like what you
see, SHARE THE PASSION! It is the biggest compliment you can give.
Follow us on Twitter @ACL_prevention and tweet about it. #DMAOnTheMove
and help us spread the passion and #movementonmovement.
Build
Athletes to Perform…Build Athletes to Last!™
Trent Nessler, PT, MPT, DPT: CEO/Founder ACL, LLC | Author | Innovator in Movement Science and
Technology. Dr. Nessler is a physical therapist and CEO/Founder of
ACL, LLC. He is the researcher and developer the Dynamic Movement Assessment™, Fatigue Dynamic Movement
Assessment™, 3D-DMA™, author of the textbook Dynamic Movement
Assessment: Enhance Performance and Prevent Injury, and associate
editor for International Journal of Athletic Therapy & Training.
For more information, please see our website at www.aclprogram.com
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