As we saw in the previous blog last week,
anything that alters the mechanics of the foot or the movements that occur at
the foot can result in abnormal force attenuation and in a closed kinetic chain,
where the feet are in contact with the ground we can see breakdown in any of
the tissues and structures above the foot and ankle as well, including those in
the lower leg. We also discussed that
many of the pathokinematics that we typically see at the foot and ankle are related
to pronation, which we noted can result in abnormal force attenuation on not
only the tissues of the foot and ankle, but also on those of the lower
leg. These effects, just as the effects
on the foot and ankle, are also significantly increased during high impact
sports due to the increased force required to participate in these types of
activities. Potential problems include,
but are not limited to:
1.
Shin
splints/stress fractures – shin splints or medial tibial stress syndrome refers
to pain along or just behind the tibia.
This is a very common injury in runners and female athletes and occurs
when there are repetitive high load activities that outpace the body’s ability
to repair the tissues or the loads are simply too high for the body to
resist. Abnormalities in lower extremity
biomechanics have been associated with increased incidence of shin splints. If shin splints persist and the underlying
mechanics are not addressed, this can lead to:
a.
Tibial stress
fractures – If the inflammation/pain is not resolved, the underlying mechanics
or causative factors are not addressed and the activity continues, it can result
in micro fractures of the tibia. This
can require prolonged care, casting and in extreme cases surgery.
b.
Anterior
compartment syndrome - in cases of shin
splints and tibial stress fractures, it is important to monitor the
athlete/patient for anterior compartment syndrome. The anterior lateral portion of the lower leg
is enclosed in a thick fibrous tissue called fascia. This fascia encloses the anterior tibialis,
extensor hallicus longus, extensor digitorum longus and the peroneus tertius
muscles. Along with this musculature, it
also includes the deep peroneal nerve and the deep tibial artery. Since the anterior compartment is an enclosed
system, swelling in this area is of major concern due to the fact that it can
compress the nerve and arterial flow to the lower leg and foot. If sufficient enough and of long enough
duration, it can cause permanent paralysis.
2.
Pulled calf muscle— the calf is composed of the
gastrocnemius and the soleus muscles. A
With
pathokinematics this is a common injury that can occur in runners and jumpers
due to excessive foot pronation or limited flexibility of the calves. Excessive pronation or decrease in
dorsiflexion with running (from tight calves), can result in abnormal force
attenuation at the calf or overwork.
Over time, this can lead to a tear or pull in the calf. pulled calf muscle can occur in either the gastronemius (more superficial) or in the soleus (more deep).
Pathokinematics Impact on the Knee:
As we move up the kinetic chain, we
see that the pathokinematics can also have as dramatic an impact on the knee as
they do the foot and ankle. As described
previously, we typically see pathokinematics in one or a combination of the
following movements at the knee:
1. Valgus
stress at the knee (as a result of hip adduction).
2. Internal
rotation of the femur on the tibia
3. Genu
recurvatum (hyperextension of the knee)
Occurrence of these in high loading
situations or with high impact sports, can alter the articulations that occur
between the bones or result in abnormal force attenuation on the tissues of the
knee. This can lead to several problems such
as:
1. Patellofemoral
issues – the articulation between the patella and femur is the patellofemoral
joint. The patella rides in a groove in
the femur from flexion to extension in a very predictable manner. For this to occur in this predictable manner,
the femur must remain in relatively “normal” alignment during closed kinetic
chain activities. When the femur falls
into valgus, internally rotated or a hyperextended position, this changes the
articulation between the two joints, potentially resulting in:
a.
Patellar tendonitis – the patellar tendon is a
continuation of the quadriceps tendon and attaches the quadriceps to the tibia
via the tibial tubercle. When the knee
moves into a valgus, internally rotated or hyperextended position, this places
excessive tensile stress on the patellar tendon. When this occurs over time and with high
impact loads, the tendon can become inflamed (patellar tendonitis).
b.
Patellofemoral syndrome/Chondromalacia – the patella
rides in the femoral groove between the medial femoral condyle (MFC) and the
lateral femoral condyle (LFC) as the knee moves from flexed This groove is higher
on the medial aspect (inside) than the lateral aspect (outside). In order to maintain alignment of the patella
in this groove with movement and to prevent abnormal wear between the groove
and the underside of the patella, the knee must move in a somewhat predictable
pattern. Any variation in alignment of
the femur on the tibia or change in the movement pattern in closed kinetic
chain activities (valgus, internal rotation, hyperextension), can dramatically
alter or change the contact area between the underside of the patella and the
femoral groove. If this occurs over time,
this can result in wearing away of the articular cartilage between the two
surfaces (chondromalacia) and ultimately result in pain (patellofemoral
syndrome). position to an extended position.
2.
Meniscal issues – the knee has two menisci (medial
meniscus and lateral meniscus) that serve as These menisci are designed to
absorb compressive forces between the femur and the tibia and aid in preserving
the articular cartilage of the femur and tibia.
The meniscuses, on the other hand, are weak when they are subjected to shearing
forces and under these conditions they are more likely to tear. Shearing force between the femur and the
meniscus occurs when there is a valgus stress or rotational (internal rotation)
stress imparted to the knee. It is
shearing forces that result in medial or lateral meniscal tears. Over time and with increased severity of the
tears, this can cause degenerative changes of the articular surfaces between
the femur and the tibia (often referred to as degenerative joint disease).cushions or shock absorbers of the knee.
3. Ligamentous
issues – the knee is composed of 4 ligaments.
The anterior cruciate ligament, the
Each one of these ligaments has a different function and force that they
resist. The two that are most commonly
impacted with the pathokinematics described here are the medial collateral
ligament and the anterior cruciate ligament.
posterior cruciate ligament, and the
medial and lateral collateral ligaments.
a.
Anterior cruciate ligament (ACL) – the ACL originates
at the medial border of the lateral femoral condyle and inserts on the tibia at
the intercondylar area. The ACL
functions as a secondary static restraint to anterior translation of the tibia
on the femur and hence aids in not only stabilizing the joint but also in protecting
the meniscus from shearing forces caused by this kind of movement. An ACL injury is a common injury in sports
and in most cases will require surgical repair in order to facilitate full
return to sport. By design, the ACL is a
good restraint to anterior translation however it is severely compromised when
rotational (internal rotation) stresses are imparted to the knee. Rotational stress creates a shearing force on
the ACL. In cases where there is a
combination of internal rotation and valgus stress to the knee, creating both
shearing force and tensile load, the ACL is compromised to an even greater
degree. This can result in either an
avulsion of the ACL where part of the bone is torn away, (seen typically only
in younger athletes), an ACL tear or an ACL rupture.
b.
Medial collateral ligament (MCL) – the MCL originates
at the medial border of the medial femoral condyle and inserts at the periorsteum
of proximal tibia, deep to the pes anserinus.
The MCL functions as a secondary static restraint to valgus stresses
imparted to the knee. By design, this
ligament is stronger in tensile load situations but weak when subjected to shear
loads. With pathokinematics, this
ligament is compromised in two ways. When
subjected to repetitive valgus stresses under high loading conditions, like
those associated with sport, increased laxity in the ligament can occur over
time. This compromises its ability to
resist subsequent high loads while simultaneously allowing increased gapping of
the joint which increases the magnitude of the load imparted to the
ligament. When there is a combination of
shearing stress (internal rotation) combined with tensile load, there is an increase
in the potential for injury to this ligament.
This can lead to MCL pain, tears or ruptures.
4. Unhappy
Triad – the “unhappy triad” terminology is used commonly in the sports medicine
literature and community in reference to a common injury involving the ACL, MCL
and the medial meniscus. This injury typically occurs in sports from
either a contact injury (where the knee is struck) or non-contact injury
(usually during a planting and twisting motion). It results from a combination of valgus
stress in combination with internal rotation (shearing stress). The typical course of treatment, depending on
the severity of the injury, is ACL reconstruction along with repair of the
meniscus tear.
5. Iliotibial
Band (ITB) Friction Syndrome – the IT band is a very thick and fibrous tissue
that originates at the tensor facia lata (TFL) at the hip and runs along the
lateral border of the femur to insert at the lateral aspect of the fibular
head. As the ITB transverses along the
lateral tibial plateau, there is bursal sac that lies between the tibial
plateau and the ITB. ITB Friction
Syndrome has often been correlated to tightness along the facial band and the TFL
and is often associated with lateral knee pain.
This syndrome is commonly seen in runners.
Next week we will look at the impact these movements have on the hip. 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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