The ankle is vulnerable to sprains
because of its location and limited movements. The ligaments support
the ankle by forming a strong attachment between the bones of the
leg and the bones within the ankle. An ankle sprain is the sudden
stretching or tearing of these ligaments supporting the ankle.
Ankle sprains occur when activity makes an unusual or sudden demand
on the ankle, such as excessive twisting and downward pressure placed
on the ankle at the same time. The affected ankle is forced beyond
its normal range of motion causing a stretching or tearing of ligaments
that support it. The seriousness of the ankle sprain and its
treatment will be determined by how fast or slow the ligaments were
The risk for an ankle sprain increases
with activities like skateboarding, and vigorous exercise programs.
Athletes who participate in sports like tennis, football, basketball,
volleyball, soccer, and skiing are at greatest risk for ankle sprains.
These activities put unusual demands on the ankle joint. Sudden
changes in foot direction with high-impact landings, place great
stress on the strength and physical limitations of the ankle.
The ankle joint provides the foot with very limited movement.
It is seen as two bony bumps at the lower end of each leg bone.
It is surrounded by three bones and held firmly together
by numerous ligaments connecting the leg to the foot. These
structures work together to give the foot the ability to move up
and down. The primary movements of the ankle are called:
- plantarflexion (pointing
the foot toward the floor)
(pointing the foot toward the ceiling)
inversion (facing the soles of the feet toward
(facing the soles of the feet away from each other).
Three bones come together to form the ankle joint:
tibia and fibula are two parallel
bones of the lower leg. These bones are attached firmly to the
ankle by strong tissues called ligaments. At the
ends of each bone, large bumps (each called a malleolus)
can be seen on the inner and outer side of the ankle joint.
talus is a smaller bone below the tibia and fibula
which supports the bones of the foot. Strong ligaments connect
each malleolus to the talus and other tarsal bones.
tarsals are the seven strong bones that support
and give structure to the foot. Their structure is similar to
that of the wrist bones.
Healthy ligaments are strong tissues that come together from different
locations and directions to provide strong support during normal
foot movement. They connect bones to each other and keep ankle movements
within normal limits. The ligaments in the ankle are named for their
location and their ability to prevent the ankle from twisting in
awkward directions. Ligaments prevent the ankle from turning inward
(inversion), outward (eversion), or
sliding forward excessively.
anterior talofibular ligament connects the fibula
to the talus. This ligament keeps the foot from turning inward
or shifting too far forward..with movement
calcaneofibular ligament connects the end of
the fibula to the heel bone. This ligament keeps the ankle from
twisting inward turning under with movement
deltoid ligament is the strongest ligament in
the foot. This ligament prevents the ankle from turning inward
beyond the normal range of motion.
Muscles and Tendons
The ankle and foot are further supported by many muscles and tendons
that work together to support the ankle joint during activity. They
also help balance the body when standing.
gastrocnemius muscle is better known as the "calf
muscle." This large muscle supports the foot and helps push
the foot into activity.
soleus muscle works with the gastrocnemius muscle
to provide support during movement while absorbing the impact
of the foot as it lands.
Achilles tendon is the largest tendon that connects
the muscles on the back of the lower leg to the heel. It helps
the ankle to move up and down during activity. The "tiptoe"
stance is accomplished by the calf muscles pulling on the heel
through the Achilles tendon.
peroneal tendons on the outside of the ankle
lie just behind the fibula. These tendons provide muscle power
to move the foot outward.
medial tendons lie behind the medial malleolus.
Their function is to support the arch while moving the foot
inward and/or bending the toes down.
What is an ankle sprain?
Ankle sprains are the stretching and/or tearing of the ligaments
that connect the tibia and fibula with the foot. The ligaments may
be slightly torn, completely torn apart, or torn away from the bones
(sometimes pulling away a small piece of bone where the ligament
The overwhelming majority of ankle sprains are inversion ankle
sprains. This type of sprain stretches or tears the ligaments
located on the outside of the ankle. An eversion ankle sprain stretches
and injures ligaments on the inside of the ankle. This occurs when
the foot turns outward from its normal position. The eversion ankle
sprain is quite rare and usually takes longer to heal.
types of sprains produce either a "high ankle sprain" or
a "low ankle sprain." The high ankle sprain damages the ligaments
that connect the lower leg bones (tibia and fibula) to each other.
The "low ankle sprain" damages the ligaments just below the ankle
near the talus.
the ankle sprain helps to insure proper treatment. There are three
grades of injury:
I- (Mild): involves a stretch of the involved ligament.
II- (Moderate): involves a partial tear of the ligament
with part of the ligament remaining intact. The joint suffers
III- (Severe): is
a complete tear of the involved ligament. The ligament may separate
completely from the bone and the joint will lose stability.
additional factor in grading ankle sprains is a "stable"
versus an "unstable" sprain. Unstable sprains require
some form of supportive treatment.