Anatomy and Physiology
Structurally the ankle is best though of as a joint containg three bones
and a multitude of ligaments.
The three bones are:
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The tibia, which forms the medial malleolus
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The fibula, which forms the lateral malleolus
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The talus. This dome shaped bone forms the top of the foot.
These bones form a mortise joint. The mortise accounts for 1/3 of
the stability of ankle rotation and essentially all of the stability of
eversion and inversion ONCE THE JOINT IS LOADED.
Therefore, ligamentous injuries are due to the process of unloading and
loading of stress.
The important ligaments form joints between the bones:
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Joining the tibia and fibula:
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Interosseous membrane
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Posterior Inferior tibiofibular ligament
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Anterior Inferior tibiofibular ligament
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Joining the medial malleous to the foot
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A large fan shaped deltoid ligament stabilizes the medial aspect of the
joint. They form a continuous band from the medial malleoulus inserting
on the navicular and talus.
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Joining the lateral malleolus to the foot
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Anterior Talofibular Ligament: 2 to 5mm thick, joining to the
neck of the talus. When the ankle is relaxed, the ligament points
dierectly foreward, perpindicular to the fibula. In this position
it may be injured due to anterior shear of the foot. However, when
the ankle is plantarflexed, this ligament shifts and becomes oriented
parallel to the fibula. In this position, the ligament can be stressed
with foot inversion. This is the most commonly injured ligament during
ankle sprains. This is the most important structure serving to stabilize
the ankle during lateral strain.
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Calcaneofibular ligament: A Strong 6mm band originating on the posterior
aspect of the lateral malleolus and inserting on the calcaneous.
This ligament is rarely injured alone, but may be injured during inversion
of the foot in neutral position. It too shifts with ankle flexion:
During neutral position of the ankle it is oriented parallel to the fibula;
during plantar flexion it is perpendicular to the fibula, and serves only
to stabilize sub-talar motion.
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Posterior Talofibular Ligament: Attaches anteriorly to the digital
fossa of the fibula, then runs back to the tuburcle of the talus.
It is rarely injured except in severe forced ankle dorsiflexion.
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Lateral Talocalcaneal Ligament: Lies between the anterior talofibular
and calcaneofibular band.
TOP CAUSES OF PAIN / DISCOMFORT
SPORTS MOST LIKELY TO CAUSE INJURY
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