Ankle joint and ligament anatomy

My orthopaedics notes for ankle joint and ligament anatomy. Source from Orthobullets.

1.  Ankle Joint
o consists of
 tibial plafond
 medial malleolus
 lateral malleolus
 talus
o motion
 main motion
 plantar flexion
 dorsiflexion
 secondary motions
 inversion/eversion
 rotation
 Distal tibiofibular joint
o consists of
 distal fibula
 incisura fibularis
 concave surface of distal
lateral tibia
o motion
 fibular rotates within incisura
during gait
 mortise widens when ankle goes
from plantar to dorsiflexion
 syndesmosis screws limit
external rotation
Primary ligaments of ankle include
o medial
 Deltoid ligament
 Calcaneonavicular ligament (Spring
Ligament)
o lateral
 Syndesmosis (includes AITFL, PITFL,
TTFL, IOL, ITL)
 Anterior talofibular ligament (ATFL)
 Posterior talofibular ligament (PTFL)
 Calcaneal fibular ligament (CFL)
 Lateral talocalcaneal ligament (LTCL)
SYNDESMOSIS
 Function
o responsible for integrity of ankle
mortise
 Anatomy
o Syndesmosis components
 Anterior-inferior tibiofibular
ligament (AITFL)
 Posterior-inferior tibiofibular
ligament (PITFL)
 deep portion of this
ligament sometimes
reffered to as the inferior
transverse ligament
 Transverse tibiofibular
ligament (TTFL)
 Interosseous ligament (IOL

Physical Exam
o test to identify a syndesmosis injury include
 external rotation test

 squeeze test
Clinical conditions
 high ankle sprain & syndesmosis injury
 ankle fracture

2. ANTERIOR TALOFIBULAR LIGAMENT (ATFL)
 Function
o primary restraint to inversion in plantar
flexion
o resists anterolateral translation of talus
in the mortise
o weakest of the lateral ligaments
 Anatomy
o extends from the anteroinferior border
of the fibula to the neck of the talus
 origin is 10mm proximal to tip of
fibula
 inserts directly distal to articular
cartilage of the talus (18mm
distal to joint line)
 runs 45°-90° to longitudinal axis
of the tibia
 Physical exam
o anterior drawer in 20° of plantar flexion
 test competency by anterior
drawer in 20° of plantar flexion
and compare to uninjured side
 forward shift of more than 8 mm
on a lateral radiograph is
considered diagnostic for
an ATFL tear
 Imaging
o stress radiographs
 more accurate in chronic injuries
o MRI : can diagnose injury
o ultrasound: more accurate than
radiographs
 Clinical Conditions
o low ankle sprains






POSTERIOR TALOFIBULAR LIGAMENT (PTFL)
 Function
o strongest of the lateral ligaments
o plays only a supplementary role in ankle
stability when the lateral ligament
complex is intact
o under greatest strain in ankle
dorsiflexion and acts to limit posterior
talar displacement within the mortise as
well as talar external rotation
o if ATFL and CFL are incompetent, then
 short fibers of PTFL restrict
internal and external rotation,
talar tilt, and dorsiflexion;
 long fibres inhibit only external
rotation, talar tilt, and
dorsiflexion
 Anatomy
o origin is posterior border of fibula
o inserts on posterolateral tubercle of the
talus
o runs perpendicular to longitudinal axis
of the tibia
 Physical exam
o no specific clinical test for isolated
PTFL injury
 Imaging
o MRI can indicate structural injury, rarely
indicated
 Clinical Conditions
o rarely injured, except in association with
a complete dislocation of the talus

3. CALCANEAL FIBULAR LIGAMENT (CFL)
 Function
o primary restrain to inversion in neutral
or dorsiflexed position
o restrains subtalar inversion, thereby
limiting talar tilt within mortise
 Anatomy
o origin is anterior border of fibula, 9mm
proximal to distal tip

o inserts on calcaneus 13mm distal to
subtalar joint and deep to peroneal
tendon sheaths
 Physical exam
o inversion (supination) test
 perform with ankle in slight
dorsiflexion
o talar tilt test
 angle formed by tibial plafond &
talar dome is measured as
inversion force is applied to
hindfoot (<5 deg is normal for
most ankles)
 useful for evaluation of
combined injury of both ATFL
and CFL ligament
 Imaging : talar tilt radiographs
o ankle arthrograms
 CFL rupture can lead to extra-
articular dye leakage into the
peroneal tendon sheath
o MRI
 Clinical Conditions
o injury occurs with ankle inversion with
the foot in the neutral position
o low ankle sprain
LATERAL TALOCALCANEAL LIGAMENT
(LTCL)
 Function
o thought to stabilize the talocalcaneal
joint
 Anatomy
o short narrow ligamentous band that
connects the lateral process of the talus
to the lateral surface of the calcaneus
o located anterior and medial to
calcaneofibular ligament
 Physical Exam
o no specific test for this ligament
 Imaging
o LTCL ligament (red arrows) identified
distinctly from the calcaneofibular
ligament

o relationship of the calcaneofibular
ligament (green arrow) and the LTCL
(red arrow)
 Clinical conditions
o often injured in conjunction with ATFL
injuries
o low ankle sprain

4. DELTOID LIGAMENT
 Function
o primary restraint to valgus tilting of the
talus
o both the superficial and deep layers
individually resist eversion of the
hindfoot
o stabilizes ankle against plantar flexion,
external rotation and pronation
 Anatomy
o superficial layer
 crosses both ankle and subtalar
joints
 originates from anterior
colliculus and fans out to insert
into the navicular neck of the
talus, sustenaculum tali, and
posteromedial talar tubercle
 the tibiocalcaneal (sustenaculum
tali) portion is the strongest
component in the superficial
layer and resists calcaneal
eversion
o deep layer
 crosses only ankle joint
 functions as the primary
stabilizer of the medial ankle
 prevents lateral
displacement and
external rotation of the
talus
 originates from inferior &
posterior aspects of medial
malleolus and inserts on medial
and posteromedial aspects of the
talus








 Physical exam
o eversion test
 with ankle in neutral, evaluates
superficial layer
 external rotation stress test
evaluates syndesmosis and deep
layer
 Imaging
o radiographs
 mortise radiograph with medial
clear space widening can suggest
injury
 gravity stress view can identify
medial clear space widening
o MRI
 normal deltoid ligament
 ruptured deltoid ligament
 Clinical conditions
o ankle fracture
 injury occurs with pronation
(eversion) trauma leading to
forced external rotation and
abduction of ankle
 may occur with fracture of the
medial malleolus
o high ankle sprain & syndesmosis injury

5. CALCANEONAVICULAR LIGAMENT (SPRING
LIGAMENT)
 Function
o static stabilizer of the medial
longitudinal arch and head of the talus
 Anatomy
o attaches from the sustentaculum tali to
the inferior aspect of the navicular
 Physical Exam
o flattening of medial longitudinal arch
o suspect injury in associated posterior
tibial tendon pathology
 Imaging
o MRI
 can diagnose tear
 (green arrow, intact
ligament; red arrow,
disrupted ligament)
 Clinical conditions
o posterior tibial tendon dysfunction
 calcaneonavicular ligament is
the most likely ligament to be
attenuated in a patient with a type
II flatfoot deformity secondary
to posterior tibial tendon
dysfunction
o acute spring ligament tear
 acute trauma can occur with
forceful landing on flat foot
 the tibialis posterior tendon is
usually normal