Archive for the ‘Knee and Ankle’ Category

12 April

Ankle and Knee Workshop: What you may not have thought about.

ankle

 

 

 

 

 

 

 

 

 

 

Notice how the calcaneus, talus and tibia stack on top of each other

 To understand the ankle, it is important to go back to the
workings of the foot.  The main bone that is part of the ankle
and the foot  is the talus.  As you can see from the diagram
above, the talus lives between the calcaneus and talus.  The
origin of the word talus is varied: a slope formed by
accumulation of rock debris, slope indicating presence of gold
under the soil, or the top of a turtle’s head.  In any of these
cases, in your body, it is a bridge between the foot (calcaneus)
and the lower leg(tibia).

Talus
To effectively use your talus, your foot needs to be grounded
onto the floor.  Being grounded on the floor means that the front
of the leg is not over active.  It allows someone to feel the
bottoms of the feet connected to the floor.  Being grounded
resembles the sensation of sinking into wet sand next to the sea
shore.  If the front of the lower leg is too tense, the movement
of the talus is inhibited.  The muscles of the front of the leg
become overactive and pull the talus away from its resting spot
on the calcaneus.  Try standing and sinking into the ground and
notice the front of the leg.  Then try lifting up the toes and
notice what your foot feels like on the ground.

The way weight is distributed through the foot is important as it
allows the talus to move freely.   The weight should be evenly
distributed between three points; the base of the first and
second toes, the base of the third and fourth toes and the center
of the calcaneus.  See the diagram below.  When your foot is on
the floor in this way, and the front of the foot is relaxed,  the
talus can move freely.  The calcaneus, talus and tibia will be
perfectly stacked.  You can feel the talus move if while sitting
on a ball, place your hand on the top of your foot, roll the ball
forward into more dorsiflexion and the talus will move back, move
the ball back and the talus will move forward.

Tibia and Fibula
The tibia, fibula and talus make up what is called the ankle.
The tibia and fibula are on either side of the talus holding it
like tongs.  This is sometimes referred to as a mortise joint.
The tibia in the inside or medial bone and the fibula is the
delicate outer or lateral bone.  Another name for tibia is flute
or reed pipe, and the other name for fibula is clasp or broach
pin.  The tibia is meant to distribute the weight of the lower
leg.  In fact, if functioning correctly it distributes 90% of the
weight of the lower leg.  The fibula on the other hand is meant
to be the delicate discretionary mover that keeps the joint on
track.  To feel the difference of how these two move differently,
sit on a chair with one leg crossing over the other.  Feel the
inside ankle bone or medial malleoli while moving your foot in
many different ways.  Then feel the outside ankle bone or lateral
malleoli.  Is there a difference?  Does one move more than the
other?

Hopefully, you will notice that the lateral or outside bone moves
more than the inside.  If it doesn’t then you may be putting too
much weight on the outside of your leg rather than on your main
weight distributer, or tibia(Franklin p. 157).

We can check this by trying to spring your fibula.  One person is
seated on a lifted table with their legs dangling off the side of
the table.  The other person is on the floor with one hand on the
distal portion of the fibula(ankle), and one hand on the proximal
end of the fibula(knee).  Gently, press the lower portion of the
ankle toward the knee.  Does the bone move?  If not massage the
interosseus tissue in between the tibia and fibula and try again.
This should loosen the area up a bit.  Also, remember to put more
of your weight through the tibia rather than the fibula.  You can
chant to yourself, ‘free the fibula.’
 

 

The knee
 femur_tibia_fibula_foot

 

 

 

 

 

 

 

 

The knee is a precarious joint.  It needs to be strong enough to
distribute weight from above and deal with forces from below,
while at the same time having a great deal of flexibility.  Eric
Franklin describes the knee joint as two pencils with the eraser
sides together and the pointed parts facing away.  Place your
fingers nearer the pointed ends of the pencil and try to keep the
eraser sides together.  Not so easy huh?  That is what your knee
deals with everyday.  A joint between two long bones, or levers
that amplify the forces coming from above and below (Franklin, p.
157).

Femur
The knee is called a double condyloid joint because of the two
rounded condyles at the end of the femur.  These rounded surfaces
fit onto the slightly convex surfaces of the tibial plateau.
Unfortunately or fortunately, the tibia plateau surface does not
provide enough support or surface area for the condyles, so the
body invented the meniscus.  The meniscus creates a very strong
but flexible surface in which the knee can move, and still
support the bodies weight.

You can feel your menisci move by placing your fingers on either
side of the joint capsule.  As the knee bends, the menisci move
back and as you extend the knee, the menisci slide forward to
support the condyles.  If you are someone who has a tendency to
pinch their menisci, this might be an exercise for you.  See if
you can feel the menisci get out of the way when you bend and
slide back in to extend.

Another great image Eric Franklin uses to describe the knee is to
think of the femoral condyles as two tires.  So, stand with your
two tires on your menisci, on your tibial plateau.  Play with
pumping up and deflating your tires.  Which do you like better?

Because the surface area of the femoral condyles is more than the
surface area of the tibial plateau, something needs to change in
order for the knee to bend.   The body has two choices:

1).  Make the tibial plateau longer to support the condyles
        rolling all the way forward and back.  They would probably         
        need to become about 6 inches or more
2). Allow the condyles to move in a more flexible way.

 Thank your body that you don’t have outrageously large lower
 legs because your body went with the second option of allowing
 the femoral condyles to move in three different ways when you
 bend and extend the knee.

Knee Movement in Flexion
When your knee bends or flexes, it rolls forward, slides back and
spins in place.
Knee Movement in Extension
When your knee extends, it rolls back, slides forward and spins
in place.

 The idea of seeing the condyles is quite helpful in this
 exercise.  If the condyles do not move this way, there will be
 increased compression in the knee joint.  Other joints will
 compensate to aide the knee in flexion and extension causing
 more force put through the knee and an increase of potential
 injury.

Lastly, you can notice from the knee picture on the last page,
that the medial femoral condyle is at more of an angle and
slightly larger than the lateral condyle.  This makes the knee
move in a spiral, like a dixie cup rolling on the floor.  As the
knee bends, the femur will externally rotate.  As the knee
extends the femur will internally rotate on a tibia that is
externally rotating.  This is called the screw home mechanism.
It allows you to stand in long lines without too much effort.

Patella
The patella of the knee is called a sesimoid bone.  It is a
floating bone, like the two underneath the big toe we looked at
earlier.  The patella is enveloped by the quadriceps (rectus
femoris, vastis lateralis, vastis lateralis oblique, vastis
medialis) to make the patella tendon that attaches at the tibial
tuberosity below the knee.  As you bend the knee, the bottom
portion of the patella lifts up like a surfer in a wave.  It is a
lever for moving the lower leg on the femur.  As you extend the
knee, the patella lies flat in its own intercondylar groove, or
patellar surface of femur between the femoral condyles.
Hopefully it is kept in that groove.  If  you feel the patella
moving out of its groove, start thinking of the quadriceps
pulling more equally  on the patella.

Tibia
So we have established that the femur moves on the tibia plateau,
but the tibia plateau can also move around the femoral condyles.
In an open chain movement, the tibia can swing around the distal
end of the femur.  It will slightly internally rotate in flexion
and externally rotate in extension.  This is a great exercise to
release tension in the knee joint.

Q-Angle
The Q-angle is formed by a line drawn from the top of the pelvis
to the center of the patella, and then from the center of the
patella to the tibial tuberosity.  A normal angle will be about
18-22 degrees.  An angle more than that will be due to wider hips
and will increase the vulnerability of patellar tracking, low
back problems, as well as pelvis leg and foot problems.  This is
called genu valgum or knock knees.  An angle less than 18 degrees
is called genu varum or bowlegs. Both can be detrimental to the
knee joint if the person allows themselves to sit into their
joint systems.

Although it can sometimes feel good to sit into your hip, or back
into your knee.  What you are really doing is putting more
pressure on the joint system than it is able to withstand for
long periods of time.  Yes, some joints are designed in such a
way to help you maintain a position for a long time without
effort.  For example, the screw home design of the knee.  Yet to
move past the point of joint stability to the far end of the
joint range and place all your weight through it is like getting
drunk and staying too long at a party.  It is not appreciated by
the body.  What is appreciated by the body is to find the neutral
position of the joint and then surround it with the support of
all the soft tissue nearby.

Bursa
There are 16 bursa in the knee.   The 4 bursae that are usually
inflamed are the pre patellar, infrapatellar, suprapatellar and
pes anserinus.  The patella bursae are generally inflamed as a
result of trauma and the pes anserinus bursa is usually inflamed
by repetitive mechanical trauma. The bursa act as little shock
absorbers in the knee joint to minimize friction.  When  there is
trauma to the area, the bursa fill with liquid to help minimize
impact.  To differentiate whether it is a swelling of the bursa
or a swelling of the joint capsule,  extend the leg on a flat
surface and press down on the patella.  If the patella rebounds
when released it most likely is one of the patellar bursas that
has swelled.

Osteoarthritis
Osteoarthritis is a progressive irreversible condition with loss
of articular cartilage that leads to pain and sometimes
deformity.  It is the normal wear and tear on the joint system.
For the knee, it is associated with obesity, trauma and poor
biomechanics.  Stiffness and pain are common symptoms.  When the condition is advanced, bone spurs can appear and prevent range of
motion.  So, range of motion, loss of strength and slow reaction
time can be the characteristics that need to be addressed.  These
can be done through Pilates, GYROTONIC(R), GYROKINEISIS(R), and balance exercises.

References
Franklin, Eric.  Dynamic Alignment Through Imagery.  Human
Kinetics. 1996.
Luder, Donna and Spencer, Stephanie. Essential Anatomy and
Equipment. 2008.
Thieme Atlas of Anatomy. 2006.