Among other knee injuries, the Anterior Cruciate Ligament (ACL)
injury is one of the most common, particularly among athletes of
high demand sports like soccer, football, basketball, gymnastics,
skiing, hockey, wrestling, lacrosse and rugby.
The knee depends on four ligaments to keep it stable:
Median Collateral Ligament - found along the inner part of the
knee, preventing the knees from bending inward
Lateral Collateral Ligament - found along the outer part of the
knee, preventing the kneeds from bending outward
Anterior Cruciate Ligament - located in the middle of the
knees, preventing the tibia (shin bone) from sliding out in front
of the femur (thigh bone).
Posterior Cruciate Ligament - also in the middle of the knees,
this ligament functions in tandem with the ACL in stabilizing the
knees. The PCL prevents the shin bone from sliding backwards
under the thigh bone.
The Anterior and Posterior Cruciate Ligaments forms a cross
inside the knees, hence the name cruciate, which means
'cross-like.? They provide support to the knees, especially
during movements that included angulation and rotation at the
The ACL is injured by twisting the knees or through an impact to
the side of the knees. In an ACL injury, the knees becomes less
stable, making sudden, pivoting movements difficult. It may also
make the knee more prone to developing arthritis and cartilage
How do you know if you have injured your Anterior Cruciate
Ligament? Four of the most common signs are: sudden giving away
of the knee, hearing a 'pop' at the time of injury, sudden
swelling of the knee joint, and pain in the knee when walking.
First aid treatment of an ACL injury is to apply RICE: Rest, Ice,
Compression and Elevation. It is recommended to have the knee
checked by a doctor to determine the extent of the injury.
Surgery is generally recommended for an athlete, which will
involve ligament reconstruction. Older and less active people may
not need to undergo surgery.
Studies has shown that there are more women who injure their
Anterior Cruciate Ligament than men. To this date, there has been
no definite answers yet, but some theories are:
Hormones - the ligaments are affected by the hormones level of
the body. According to the studies, women in pre-ovulatory phase
are more prone to ACL injuries. Women on oral contraceptives are
thought to have lower risks.
Difference in ACL shape - because females have smaller frames
than males, they have slighty smaller ACL (on the average), and
the place where the ACL passes through the knee joint (the
intercondylar notch) is also smaller. This may account for
greater ACL injury susceptibility.
Upright position in sports - Studies has shown that ACL is
usually injured when the athlete is in more of an upright
position, like volleyball. Men are figured to participate more in
sports wherein they are in a crouching position, like soccer or
Wider pelvis - the female body has a wider pelvis than men.
This anatomic difference has been studied as a cause of gender
discrepancies in injury rate. This increases the quadriceps angle
(angle formed by the intersection of a line from the anterior
superior iliac spine to the center of the patella and a line from
the center of the patella to the tibial tubercle), which has long
been linked to anterior knee pain.
Muscle structure - the imbalance between hamstring and
quadriceps muscle strength is another factor for increased ACL
injuries among women. Men tend to have more developed thigh
musculature than women. Stability of the knee is through to be
more muscle-dominant in men, ligament-dominant in women. Female
athletes' dominant muscle group are the quadriceps, which is an
ACL antagonist. Male athletes, on the other hand, is hamstring
Exercises to strengthen the knees to help prevent ACL injuries
Six-way lunge with arm drop
The six-way lunge stretches and strengthens the hamstring muscles
at the back of the thigh in all three planes of motion. Strong
and flexible hamstring muscles assists the ACL in its job of
controlling the knee joint and preventing the tibia from moving
excessively during knee flexion.
Stand with your feet parallel and hip-width apart. Bend your
arms at the elbows so that your hads are directly in front of
Take a long step forward with your right foot, as if you were
doing a lunge. Lean your upper body forward, approximately 45
degrees at the waist as you do so. Drop your hands on either side
of your right knee as your right foot makes contact with the
Quickly extend your right knee by straightening your right leg,
and bring your body back to the starting position. Repeat with
Again, from the starting position, step directly to your right
with your right foot into a lateral-lunge position. Your upper
body whould also face to the right, and it should lean forward
over your right leg at approximately 45 degrees from the vertical
position. Again, drop your hands on either side of your right
knee as your right foot touches the ground. Your left foot must
remain pointing straight ahead.
Extend your right knee and return your body to the starting
position. Repeat with the left leg moving to the left.
Lastly, from the starting position, twist your body around at
the hips and step diagonally and to the rear with your right foot
in a backward-lateral-lunge position. Your upper body should face
to the right-rear at about 'four o'clock.' It should also be
inclined over your right leg at approximately 45 degrees from the
vertical. Drop your hands on either side of your right knee as
your right foot touches the ground. Your left foot must remain
pointing straight ahead. Quickly extend your right knee and
return your body to the starting position. Repeat the overall
motion with your left leg, moving it to the left-rear (eigth
Repeat entire sequence three times for a total of 18
repetitions of stepping. Rest for 30 to 60 seconds, carry out 18
repetitions again. Rest for 30 to 60 seconds, and perform the
last 18 repetitions for a total of 3 sets. Progressively toughen
the exercise over a period of four to six weeks by increasing the
resistance held in your hands (small dumbbells) and the speed of
Zig-zag runs help develop the balance and body control required
to move in multiple directions at various speeds. These runs
require the knee joints to move through a number of different
angles and directions, thus mimicking movements which can lead to
an ACL injury in unprepared athletes.
Begin by running at half-speed straight ahead for about five
At the five-meter mark, cut quickly to your left for several
strides by pushing off your right foot and moving in a
left-forward (diagonal) direction.
Then cut back toward the right for several strides by pushing
off your left foot and moving in a right-forward direction.
Repeat this sequence for a total of eight to ten cuts (four to
five to the right, four to five to the left). Perform three to
five sets of this exercise with a break of 30 to 45 seconds
between each run.
Gradually increase the intensity of your zig-zag runs over a
period of four to six weeks by running faster and also by
changing the number of strides between direction changes. Vary
the number of numbers strides between one and five. You can also
complete some of these sets in a backward direction.