Throughout this series we have seen the impact that pathokinematics has on the lower kinetic chain As
described previously, we typically see pathokinematics in one or a combination
of the following movements at the hip:from the foot to the knee. As we continuing to move up the kinetic chain, we see that pathokinematics impact the hip as they do the knee, foot and ankle and the structures inbetween.
1. Hip
adduction
2. Hip
internal rotation
3. Trendelenburg
(dropping of the pelvis on the contralateral side during weight bearing on the
ipsilateral side).
If these occur in high loading
situations or during high impact sports, the angles of the articulating
surfaces can be altered, and the length tension relationships of the musculature
supporting the hip/pelvis can change and/or we can see abnormal force
attenuation on the tissues of the hip.
This can lead to several problems:
1. Posterior
and lateral hip issues – the hip (in general terms) is the articulation between
the head of the femur and the acetabulum.
The bony architecture of this ball and socket joint allows for a
tremendous amount of stability, while also allowing for some considerable range
of motion in multiple planes. There is
also a significant amount of musculature that provides additional stability to
the joint and which also provides motion.
The hip, like most joints in the body, is designed to be loaded in a
particular fashion. Moving outside of
this “ideal” position, repetitively and under high loads, can result in tissue
breakdown and degenerative changes in the joint. With pathokinematics, we tend to see the
femur in an adducted and internally rotated position along with trendelenburg
at the hip. One of these motions alone
can add to increased stress to the tissues and musculature which is designed to
resist these motions. When in
combination with each other and under high loads, this can cause lateral hip pain
and conditions such as:
a.
Trochanteric Bursitis – the trochanteric bursa is a
bursal sac located between the greater trochanter of the femur and the tensor
fascia lata (TFL). This is designed to
reduce the wear and tear on the TFL from the bony prominence underneath
(greater trochanter). When there is
increased tensile and compressive loads to this tissue (with hip adduction,
trendelenburg and internal rotation) then the tissue will respond with
inflammation. Inflammation of this
tissue is referred to as trochanteric bursitis and will present itself as
lateral (or slightly posterior lateral) hip pain.
b.
Hamstring strains – the hamstrings cross two joints,
the hip and the knee and are composed of three heads, the biceps femoris
(lateral aspect), semimembranosus and semitendinosus (medial hamstring). The hamstrings function to flex the knee and
to aid in hip extension in a closed kinetic chain. With excessive pathokinematics, the hamstrings
are compromised in two primary ways:
i. Increased
work - with trendelenburg gait, hip adduction and internal rotation, there is
often accompanying gluteus maximus (GM) weakness. If the GM is weak, especially in athletes
whose sports require rapid acceleration (sprinters, soccer players, football
players, basketball players) then the hamstrings will become over active in an
attempt to assist with rapid hip extension.
Since the hamstrings are picking up part of the load traditionally
provided by the GM, then the hamstrings can easily become overworked resulting
in hamstring pulls, tears and ruptures.
ii. Increased
load – with the same mechanisms above (trendelenburg, hip adduction, internal
rotation) combined with increased force attenuation (since less force is
absorbed at the foot/ankle and knee), the hamstring is put under an even higher
tensile load and this can result in irritation.
If this irritation outpaces the body’s ability to repair it before the
next work/loading session, this can again lead to an increased potential for
hamstring pulls, tears and ruptures.
c.
Piriformis syndrome – the piriformis is a muscle deep
in the hip that originates at the anterior This muscle serves to
provide some component of external rotation to the femur on the acetabulum and
some component of hip abduction. In a
closed kinetic chain, this muscle is put under a tremendous tensile load when
there is hip adduction, trendelenburg and internal rotation. If these motions occur in the presence of
weakness of the gluteus medius (which is a much larger muscle much more
equipped to resist these motions) then the piriformis continues to attempt to
resist some component of these motions without the support of the larger and
more powerful muscle. This results in
the smaller piriformis muscle becoming overworked and strained. When this muscle becomes strained, it will typically present in one of the following ways:
sacrum and superior margin of the greater sciatic notch and inserts at the superior medial portion of the greater trochanter.
i. Deep
posterior gluteal pain – with deep posterior gluteal pain, the piriformis will
often develop a trigger point along with pain which radiates inferior or
superior from that trigger point. This
most often will result in posterior gluteal pain which is increased in
sitting. If this is in fact the cause of
posterior gluteal pain, it is easily diagnosed with a piriformis stretch in a sitting
position. Pain is elicited with the
stretch and upon release of the position relief is provided. We often tell patients, if this stretch is
done correctly, you will experience slight pain during the stretch (we do not
want to stretch to the point of significant pain) and relief from this pain
upon release.
ii. Sciatica
– the sciatic nerve is a nerve that originates from L4-S3 and runs the entire
length of the upper and lower leg Sciatica is a term that is often over used in
sports medicine and is often a catch all term for any pain which radiates down
from the gluteal region to the lower leg.
With radicular symptoms, it is important to determine if this is coming
from the lumbar spine, nerve root irritation or entrapment or compression of
the sciatic nerve at the bifurcation of the piriformis. For our purposes, we will use the term
sciatica to describe conditions just related to the sciatic nerve. With pathokinematics, the nerve is put under
a tremendous amount of tensile load with excessive hip adduction, especially
when combined with a trendelenburg. If
this occurs with high loading activities or occurs repetitively, then there is
an increased potential for the nerve to become inflamed or compressed by the
piriformis. Since nerves are vascular
tissues, this tensile load and/or compression will result in an inflammatory
response by the nerve. This will result
in radiating pain. When this is the
result of entrapment or compression of the nerve from the piriformis, it
typically starts as deep posterior gluteal pain (piriformis syndrome), then
progresses to radiating pain that can radiate down to the lateral calf. Whether
it starts as radiating pain or deep gluteal pain that radiates down the leg,
identification and early intervention is critical to a quick recovery.
iii. Deep
posterior gluteal pain with sciatica – worst case scenario is the combination
of both of the above conditions. You
will typically see this in the athlete who has been attempting to work through
piriformis syndrome allowing it to progress to sciatica. In extreme cases, this can involve lengthy
rehabilitation which is easily exacerbated with some of the typical
interventions we use. Therefore, early
identification and intervention is key to a quick and speedy recovery and
return to sport in this case.
2. Anterior
hip issues – in discussion of the anterior hip, in particular the hip flexor, we
will also briefly discuss deeper internal structures of the hip that are
impacted with pathokinematics.
a.
Deeper internal structures – the most common deep
structures that are impacted with pathokinematics are the labrum of the
acetabullum and the articulating surfaces between the femur and the
acetabullum. Although these are impacted
with pathokinematics, they appear to be more impacted with repetitive high
loading situations, especially when seen in combination with an increased
magnitude and peak amplitude with each step imparted to the tissues.
i. Labral
Tears – the acetabular labrum is a thick cartilage that runs the circumference
of the acetabulum. This structure
increases the contact area and deepens the acetabulum which provides some increased
stability to the joint. The labrum of
the hip, much like the labrum in the shoulder, is designed to mitigate
compressive forces and will wear more quickly when combined with shear
stresses. The acetabular labrum is put
under increased compression and shearing stress when there is the combination
of hip adduction and internal rotation or trendelenburg. In closed kinetic chain situations and with
repetitively high loads, the labrum can tear.
This most commonly occurs on the anterior superior aspect of the labrum
and will usually result in anterior groin pain.
Labral tears are often hard to diagnose and usually have to be done via magnetic
resonance imaging.
ii. Early
onset of degenerative joint disease (DJD) – the articular Much like the articular cartilage of the
knee, the articular cartilage of the hip is strongest under compressive forces
and weakest when subjected to shearing forces.
Shearing forces imparted to the cartilage causes it to break down
faster, crack and fissure and ultimately can lead to it being worn away completely,
resulting in bone on bone articulation. According
to recent studies abnormal movement patterns may be the number one predictor of
arthritic changes in the joint and can lead to total joint replacements later
in life. Wearing of the articular
cartilage and early onset of DJD can result in anterior groin pain and crepitus
(audible or palpatable grinding) in the hip. surfaces of the femur and the acetabulum are covered with articular cartilage which essentially allows for smooth and pain free range of motion of the hip.
b.
Hip flexor tendonitis – with the stresses that are
associated with pathokinematics as well as some commonly seen tightness (lack
of hip extension) and weaknesses (decreased hip extension strength), there is
an increased amount of stress that is imparted to the hip flexors. With pathokinematic movement patterns in
particular, we also tend to see significant tightness of the anterior hip
(specifically the rectus femoris and iliopsoas). Increased tightness and associated decrease
in hip extension, during sport related activities can increase the potential
for a rapid over stretch of these muscles resulting in an inflammatory
response.
Let’s take a look at an
example. Here we are looking at a black
belt in karate complaining of hip pain and decreased ability to kick with
significant force with the right leg.
This has been going on for some time and she is experiencing more and
more difficulty participating in her sport as time goes on. When looking at this athlete’s mechanics, she
demonstrates a significant amount of adduction at the hip with a single leg
squat as well as during other functional movements.
Looking closely at the amount of
adduction at the hip and the force vector represented in this picture, you can
see that in this case, with single leg kicking activities, there would
naturally be an increase in the amount of shear stress at the hip and particularly,
increased tension to the structures of the lateral aspect of the hip. This athlete is at risk for hip bursitis, hip
arthritis, hip labral tears, groin strains and increased stress to the
sacroiliac (SI) joint of the lower back.
In addition to risk of these types
of injuries, this athlete’s kicking performance as measured by power output,
force and torque, is compromised as she reports. Pain and injury can be causative factors
here, but also once again we see that the normal kinetic chain is interrupted
and power is diverted away from the lower extremity (foot and ankle in this
case) and instead is lost at the knee instead.
In this athlete’s sport, karate, it is critical to channel as much core
strength through the entire chain and out at the point of contact with the
opponent.
Next week we will look at the impact these movements have on the lumbar spine and sacrum. If you like what you read the biggest compliment you can give to us is to share the passion. Follow us on Twitter @ACL_prevention or on Facebook at Athletic Therapy Services. Remember #MoveRight, last longer and perform better!
Dr. Nessler is a practicing physical therapist with over 17 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment. He is the developer of an athletic biomechanical analysis and author of a college textbook on this subject. He serves as the National Director of Sports Medicine for Physiotherapy Associates, is a Safety Council Member for USA Cheer National Safety Council and associate editor of the International Journal of Athletic Therapy and Training.
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