ANKLE ANATOMY AND

BLOOD SUPPLY OF TALUS

 ANKLE ANATOMY
• Ankle is a synovial joint of hinge
variety.
• Ankle is a three bone joint composed
of the tibia, fibula and talus.
• Talus articulates with the tibial
plafond superiorly, posterior
malleolus of the tibia posteriorly and
medial malleolus medially.
• Lateral articulation is with malleolus
of fibula .
• The joint is considered saddle-shaped with
dome itself is wider anteriorly than posteriorly
and as the ankle dorsiflexes, the fibula rotates
externally through the tibio fibular syndesmosis
accommodate this widened anterior surface of
the talar dome.
• Inferior tibiofibular joint is the syndesmosis
joint.
TIBIA
• Lower end formed by five surfaces, inferior, anterior,
posterior, lateral& medial.
• Posterior border is lower than the lateral border.
• Lateral border is concave with two tubercles anterior
and posterior.
• Anterior tubercle over laps fibula - forms the basis for
radiological tibio-fibular syndesmotic assessment.
• Posterior tubercle remains intact -forms the basis for
indirect reduction of posterior malleolar fragment
 MEDIAL MALLEOLUS
• Extension of the distal tibia.
• Inner surface covered with articular
cartilage and articulates with the medial
facet of the talus.
• Distal, inner surface of the malleolus
divided by a longitudinal groove Into
• a) Anterior colliculus (larger) - provides
attachment to superficial deltoid ligament.
• b)Posterior colliculus (smaller) - provides
attachment to deep deltoid ligament
 LATERAL MALLEOLUS
• Extension of the fibula.
• Just above the ankle joint, the fibula sits in a groove over
distal tibia
• No articular surface between the distal tibia and fibula.
• Distal end is tapered and has a posterior groove for the
peroneal tendon
• Ligaments attachment at lateral malleolus
a) Anteriorly - anterior tibio-fibular ligament and Anterior
talo-fibular
b) Inferiorly - calcaneo-fibular ligament
c)posteriorly - posterior tibio-fibular ligament
DISTAL FIBULA
• Static buttress for the talus
• The fibula bears one sixth of the weight transmitted downward from
the knee during static weight bearing
• The distal fibula moves distally (average 2.4 mm) when moving from
non-weight bearing to weight bearing. (Pulled distally by the active
contraction of the flexors of the foot).
• This distal movement may increase ankle stability by deepening the
mortise and by tightening the interosseous membrane, thereby
pulling the fibula medially
ANKLE MORTISE

• The bony arch formed by the tibial plafond and two malleoli is
referred as the ankle "mortise“
• Tenon (talus) made to fit in arch.

• MORTISE JOINT:
A joint made by a mortise and tenon.
• 1. MORTISE - tibia and fibula
• 2. TENON - talus
ANKLE JOINT (Talocrural joint)
• Ankle is actually made up of two joints:
1. Sub talar joint
2. True ankle joint.

1) SUBTALAR JOINT
A. It consists of the talus on top and calcaneus on the bottom
B. The subtalar joint allows side to side motion of the foot.( inversion
and eversion)
2) TRUE ANKLE JOINT:
The true ankle joint is composed of 3 bones
Tibia which forms the inside, or medial, portion of
the ankle.
Fibula which forms the lateral, or outside portion
of the ankle
Talus underneath.
The true ankle joint is responsible for up and
down ( dorsiflexion and plantarflexion of foot)
 LIGAMENTS OF THE JOINT
CAPSULAR LIGAMENT WITH SYNOVIAL MEMBRANE
• Ankle joint has Fibrous capsule which surrounds the joint and
attached all around the articulate margin with two exceptions
1. Posterò-superiorly it is attached to inferior transverse tibio-fibular
ligament
2. Anterio inferiorly it is attached to dorsum of neck of talus at some
distance from trochlear surface
• Thin in front & behind.
• Thick on either side where it blends with collateral ligaments.
SYNDESMOTIC LIGAMENT COMPLEX
• Between distal tibia & fibula.
• Resist axial, rotational, & translational forces to maintain the
structural integrity of mortise.
LIGAMENTS
1) Anterio inferior tibio fibular ligament
2) Posterio inferior tibio fibular ligament
3) Inferior Transverse ligament
4) Interosseous ligament
(a) ANTERIOR TIBIOFIBULAR LIGAMENT
• Originates from anterior tubercle and anterolateral
surface of tibia. Runs obliquely to the anterior fibula.

(b)POSTERIOR TIBIOFIBULAR LIGAMENT

• Originates from posterolateral tubercle of tibia.
Inserts on posterior fibula. Stronger and thicker than
anterior.

(c)TRANSVERSE TIBIOFIBULAR LIGAMENT

• Considered part of the posterior tibiofibular ligament
complex.
• Deepens the posterior aspect of the ankle joint.

(d)INTEROSSEOUS LIGAMENT
• Extension of the interosseous membrane
• Main transverse stabilizer of tibiofibulararticulation.
Triangular in shape.
LATERAL LIGAMENTS
1) Talofibular ligaments: from the
lateral malleolus of the fibula to
connects talus and support the lateral
side of the joint. Not as strong as the
medial ligaments, because lateral
support for the ankle is also provided
by fibula
Divided in:
• Anterior Talofibular Ligaments: It is
prevents anterior subluxation of
talus when ankle is in plantar flexion.
• Posterior Talofibular Ligament: It is
prevents posterior and rotatory
subluxation of the talus.
2) Calcaneo fibular ligament: connecting lateral malleolus to calcaneus.
• It acts primarily to stabilize sub-talar joint & limit inversion(prevents
inversion when ankle is in dorsiflexion)
•MEDIAL LIGAMENTS
a) Superficial deltoid ligament
b) Deep deltoid ligament
A. Superficial deltoid ligament-
1. Originates primarily from anterior
colliculus of medial malleolus.
2. Tibiotalar portion.
3. Tibionavicular portion suspends the
spring ligament and prevents inward
displacement of talus.
4. Tibiocalcaneal portion prevents valgus
displacement of calcaneous
• B. Deep deltoid ligament
(Deep portion of tibio talar ligament)(Intra-articular portion)
1. Originates from posterior border of the anterior colliculus,
intercollicular groove and posterior colliculus.
2. Inserts into medial surface of the talus.
3. Primary medial stabilizer of ankle, prevents lateral displacement of
talus.
TENDONS AND NEUROVASCULAR
STRUCTURES
Divided into four group
a) Posterior Group
b) Anterior Group
c) Medial Group (posterior to the medial malleolus)
d) Lateral Group (posterior to the lateral malleolus

(a) Posterior Group

1. Achilles.
2. Plantaris
(b)Anterior Group
• Superficial to Extensor Retinaculum
1. Superficial peroneal nerve (lateral to anterior
midline)
2. Saphenous nerve (medial to anterior midline)
3. Long saphenous vein (accompanying saphenous
nerve)
• Deep to Extensor Retinaculum (from medial to lateral)
1. Tibialis anterior
2. Extensor hallucis longus
3. Deep peroneal nerve
4. Anterior tibial vessels
5. Extensor digitorum longus
6. Peroneus tertius
(C) Medial Group (posterior to the medial
malleolus)
Deep to Flexor Retinaculum (from anterior to
posterior)
1. Tibialis posterior
2. Flexor digitorum longus
3. Posterior tibial vessels
4. Tibial nerve.
5. Flexor hallucis longus
(D) Lateral Group (posterior to the
lateral malleolus)
Superficial to Peroneal
Retinaculum.
1. Sural nerve (posterior to fibula)
2. Short saphenous vein
(accompanying sural nerve)

Deep to Peroneal Retinaculum.

3. Peroneus longus (more
external)
4. Peroneus brevis
 BLOOD SUPPLY OF ANKLE JOINT
1. Anterior tibial artery
a) Anterior medial malleolar artery- supplies
medial malleolus
b) Anterior lateral malleolar artery- supplies
lateral malleolus
2.Posterior tibial artery
a) Posterior medial malleolar- supplies medial
malleolus
3. Peroneal artery
a)Perforating artery- joins with anterior malleolar
artery and direct supply to posterior talus
b)Posterior lateral malleolar artery- Supplies
lateral malleolus
 NERVE SUPPLY

• Anterior aspect of joint – capsule

receives innervation from articular
branches from
saphenous,superficial and deep
fibular nerves
• Lateral- Sural and superficial
fibular nerve
• Medially and Posteriorly –
Saphenous and tibial nerves
ANKLE BIOMECHANICS
• Locking and unlocking of the ankle joint
1. During dorsiflexion, the wide anterior part of the trochlear surface of
the talus is lodged into the narrow posterior part of the superior
articular surface (socket).In this position; the ankle joint is locked as the
foot cannot be moved from side to side
2. During plantar flexion, the narrow posterior part of the trochlear
surface is lodged in the wide anterior part of the socket. In this
position, the ankle joint is unlocked as the foot can be moved slightly
from side to side.
 TALUS
• INTRODUCTION:
• TALUS – Astragalus in greek means "ball of the ankle joint“
• Talus was a gaint, bronze god with a singular large vein coursing
through his body.
• Talus is the second most commonly fractured tarsal bone.
• No muscular attachments
• Incidence of fracture - 0.14%- 0.9% of all fractures- 5 to 7% of foot
fractures
HISTORY
• Roman Times- The heel bone of horse was used as dice and was called
Taxillus. This Word evolved into Talus.
• Year 1500-Talus Fracture was first described by Egyptians.
• Year 1608-Fabricius Von Hilden -Reported fracture dislocation resulting
in Talectomy.
• Year 1882- SHEPARD- Described fracture of lateral tubercle in English
literature. Fracture often referred to as "Shepard fracture“
• Year 1919- Anderson(Royal flying corps) reported the first series of talar
neck fractures in World War I coined the term Aviators Astragalus.
• YEAR 1943-BLAIR described talectomy of the Talus body with tibial slide
fusion to the head and neck of talus.
• Year 1970- Hawkins- presented classification of neck of talus fracture
based on pattern of injury and disruption of blood supply. He also
determined the risk of osteonecrosis to talar dome.
• YEAR 1972- Canale and Kelly Expanded theHAWKINS classification
system and introduced type 4-pioneered specific radiographic
techniques for talus
• • Year 1974-Cedell's- Described fracture of medial tubercle of the
posterior process. Referred as "Cedell'sfracture"
ANATOMY
• Second largest tarsal bone.
• Ossification - from one primary centre which
appear in“6 th month of intrauterine life. The
posterolateral process sometimes fuses with an
accessory bone called Ostrigonum.
• No muscular or tendinous attachments.
• Curved head, intermediate neck portion, large
trapezoidal body.
• Articulates with the navicular, calcaneus, tibia
and fibula.
• Body entirely covered by articular
cartilage (70%).
• Superior surface is convex from front to
back and slightly concave from side to
side. Dome is trapezoidal.
• Anterior surface is wider than posterior
surface (average2.5 mm). Medial and
lateral articular facets present over body.
• .• Neck has no articular surface. And is
the site of access for Blood supply to
rest of the talus.
PARTS OF TALUS
1. HEAD
2. NECK
3. BODY (A.LATERAL PROCESS, B.POSTERIOR PROCESS)
• HEAD OF TALUS (Caput)
Anterior articular surface is large, oval and convex articulating with
navicular bone.
Inferior surface have two facets anterior and middle for articulation
with Calcaneum.
NECK OF TALUS (Collum)
• The neck is the segment of bone located between the body and the
head.
• Its average length is 17 mm, with a maximum of 23 mm and a
minimum of 12 mm.
• Directed forward, medial, downward.
• Relatively thin diameter makes it weaker area and hence more
vulnerable to fractures.
BODY OF TALUS
• 5 surfaces:-
I.Superior surface
II.Inferior surface.
III.Medial surface
IV.Lateral surface
V.Posterior surface
• Superior surface of the body presents, a smooth
trochlear surface, the trochlea for articulation with the
tibia.
• The trochlea is broader in the front than behind, convex
from backward, slightly concave from side to side.
 INFERIOR SURFACE
• Two articular areas, the posterior and middle
calcaneal surfaces, separated from one another by
a deep groove,Sulcus tali.
• The groove runs obliquely forward and lateral side.
In the articulated foot it lies above a similar groove
upon the upper surface of the calcaneum( sulcus
calcanei) and forms a canal (Sinus tarsi) filled up
by interosseous talo calcaneal ligament.
• The posterior articular surface is large, oval form
and its articulates with the upper surface of
calcaneum.
• The middle calcaneal articular surface is small, it
articulates with the upper surface of the
sustentaculum tali of the calcaneus.
• Medial surface: present at its upper part a pear-shaped articular
facet for the medial malleolus. Below the articular surface is a rough
depression for the attachment of the deep portion of the deltoid
ligament of ankle joint.
Lateral surface:

• It carries a large triangular facet concave from above downward for

articulation with lateral malleolus. Superiorly, it is continuous with the
trochlear surface; inferiorly, its apex is a lateral process.
• The lateral talo-calcaneal ligament inserts on the apex of the lateral
process & anterior talo-fibular ligament attach anterior part of lateral
process.
 Posterior surface:
• It is narrow and has two tubercles, medial and lateral tubercle
and a groove in between for flexor halluces longus tendon.
• The posterior talofibular ligament is attached to the lateral
tubercle of the posterior process (posterolateral tubercle).
• The posterior talocalcaneal ligament is attached to the plantar
border of the posterior process.
• The medial talocalcaneal ligament is attached below to the
medial tubercle, where as the most posterior superficial fibres
of the deltoid ligament are attached above the tubercle.
• The lateral tubercle is sometimes separated from the rest of
the talus and is then known as Os trigonum
• . It is seen in50% of normal feet.
BLOOD SUPPLY OF TALUS
• Its sparse because 3/5th of talus or 70%
of talus covered by articular cartilage.
• Blood supply is through extraosseous
and intraosseous blood supply.
A.Extra-osseous blood supply is through:
1.Posterior tibial artery
2. Anterior tibial artery ( dorsalis pedis)
3. Peroneal artery
These three main arteries reaches talus
through vascular network that covers all
its cartilage free surfaces
47% blood supply comes from posterior
tibial artery
i)Anterior Tibial artery (dorsalis pedis)
• Medial tarsal artery supply Talar head
• Anteromedial malleolar artery branch supply superior talar neck
• Anterolateral malleolar artery supply talar neck and also anastomosis with
perforating peroneal artery and that becomes the artery of tarsal sinus
ii)Posterior Tibial artery
• Artery of the tarsal canal (deltoid branch) supply Medial surface of talus body &inferior half
of the talus head
• Second branch forms vascular plexus by the calcaneal branch and an anastomosis with
branches of peroneal artery to supply medial tubercle of talus.
iii)Perforating Peroneal artery
• Peroneal branch anastomosis with calcaneal branch supply to Posteromedial tubercle
• Perforating peroneal artery anastomosis with other vessels to form the artery of tarsal
sinus and supply neck
ARTERY OF SINUS TARSI :

• It is the anastomoses among various arteries of the lateral region of

the foot. These included the anterior lateral malleolar and proximal
lateral tarsal arteries in all cases. In seven specimens an additional
branch was from the distal lateral tarsal artery, and in the remaining
three specimens, an additional anastomotic branch was from the
peroneal artery
• Principle supplier of intrasinus structures
ARTERY OF TARSAL CANAL
• The posterior tibial artery gives rise to the artery of the tarsal canal
about 1 cm proximal to the origin of the medial and lateral plantar
arteries. This artery of the tarsal canal passes anteriorly between
the sheaths of the flexor digitorum longus and flexor hallucis longus
muscles to enter the tarsal canal.
• It anastomoses with artery of tarsal sinus to form the artery of
tarsal sling
• The arteries of the tarsal sinus and tarsal canal, together with the
medial periosteal network, are the most important sources of blood
supply to the talus
B.Intra-osseous blood supply
Head is supplied from two sources
• Medial Superior half is supplied by dorsalis
pedis artery Branches.
• Inferior half is supplied directly from artery
of tarsal sinus.
• Body of talus is supplied by the anastomotic
artery of tarsal canal. This artery gives four to
five branches into the body.
• It is the most consistent major blood supplier
of the body of talus.
• The deltoid branches which enter the body
on its medial surface, supplies medial quarter
or one third of body of talus.
• The branches from the posterior periosteal
network which enter the posterior tubercle
supply area limited to the posterior tubercle
region.
• These intra-osseous vessels anastomose in
60% of the specimens.
• This incomplete anastomtic blood supply may
explain the variable incidence of vascular
necrosis of the talar body with talar neck
fractures.
• CLINICAL PRESENTATION.
Talus fractures frequently occur in a young, active and mobile
population with history of high velocity injury .
Clinically:
1.Intense pain, unable to move ankle.
2.Gross oedema and echymosis usually present.
3.When there is subluxation Or 75°dislocation the normal contours of
ankle and hind foot are distorted.
4.Open injury may occur if there is significant distortion.
DIAGNOSIS

• Radiographic evaluation
1)X-rays:
Anteroposterior views
• Ankle mortise view- alignment of talar body in
mortise
• Lateral view-best shows talar neck line and
alignment of the posterior facet of the subtalar
joint
 CANALE AND KELLY VIEW

• View of the talar neck achieved by

internal rotation of the foot by placing
foot plantigrade on an ×-ray film &
angling the beam at 75 degrees to the
perpendicular.
• Gives best view of talus neck
• Useful intra operatively to check
alignment of neck.
CT SCAN
• In case of comminution and to identify fractures entering the articular
surfaces of the talus.
• It would also help to plan the screw placement by avoiding the fracture
line.
• Confirms truly undisplaced fractures.Demonstrates subtalar
comminution, osteochondral fractures.
• MRI SCAN :
• It demonstrates osteonecrosis most effectively.
• Use of titanium screws have been preferred if AVN of bone is suspected.
TALUS NECK FRACTURE( AVIATOR’S
ASTRAGALUS)
• Incidence-30%oftalarfractures
• Mode of injury:-Flying accidents are most common source of the
fractures with the sole of the foot resting on rudder bar of the aircraft
• Motor vehicle accidents
• Fall from height
Mechanism of injury: Forced hyper-dorsiflexion of the ankle, axial load
to the plantar foot.
 HAWKINS CLASSIFICATION
Hawkins 1970-talar neck fractures into three
type
• Canale and Kelly added type IV in1972
• Based on displacement of body of talus.
• Useful to perdict long term outcome and
development of AVN of talar body
Type I - Undisplaced vertical fractures of the
neck
Type II - Displaced fractures with subluxation
or dislocation of the subtalar joint
Type III -Displaced fractures with
dislocation of both ankle &sub talar
joint

Type IV-Displaced fractures of talar

neck with dislocation of the body
from ankle or subtalar joint with
additional dislocation or subluxation
of talonavicular joint
AVASCULAR NECROSIS OF TALUS
• Avascular necrosis , also known as osteonecrosis or aseptic necrosis ,
is a common complication occurring after a talar neck fracture.
• Development mainly related to degree of displacement of talar neck
fractures- which in turn results in damage to blood supply of body
fragment.
• With in 8 weeks of injury, a very small percentage of non displaced
fractures and a very large percentage of fractures with complete
dislocation of the body will be complicated by osteonecrosis.
HAWKIN’S SIGN
• The "Hawkins sign" is a well-described
radiographic indication of viability of the
talar body.
• Between 6 and 8 weeks after injury, a
thin line of subchondral atrophy along
the dome of the talus(Hawkins sign)
seen on an antero-posterior radiograph
indicates the presence of vascularity and
excludes the diagnosis of osteonecrosis.
• If the Hawkins sign is not present,
however, osteonecrosis may or may not
occur ;the sign 100% sensitive but only
58% specific.
 MRI
• Double line sign – hypointense outer line
(sclerosis and fibrosis) and a hyperintense
inner line (granulation tissue)
Thordarson et al used MRI to classify AVN
• Type A: no abnormal signal changes in the
body
• Type B: signal changes less than 25% of the
body
• Type C: signal changes 25 to50% of the body
• Type D: signal changes more than 50% of the
body
OSTEOCHONDRAL LESSIONS OF
TALUS
• It is an injury to smooth surface on the ends of bones, called articular
cartilage(chondro) and the bone (osteo) underneath it also known as
transchondral (osteochondral) fracture caused by trauma.
• Also called as osteochondral dessicans of talus.
• Caused may be due to traumatic events or result of repetitive
microtrauma.
• Frequently encountered with talus neck and body fractures.
Pathogenesis
• The controversy over uniform terminology partly results from the lack of a clearly
defined
• . In 1922- Kappis first applied the term osteochondritis dissecans to the ankle joint.
• In 1959- Berndt and Harty’s in which the term transchondral fracture of talus
proposed.
• In 1966, Campbell and Ranawat- concluded that osteochondritis is a disease process
resulting in a pathologic fracture through necrotic bone as a result of ischemia.
• The argument for idiopathic osteonecrosis as the underlying disease is supported by
the fact that trauma is not documented in all cases of osteochondral lesions of the
talus.
• Canale reported that all lateral talar dome lesions were associated with trauma,
whereas 64% of medial lesions had experienced a traumatic event, a theory
supported by several authors.
• More recently, Elias proposed a grid system to
better localize talar dome lesions.
• They evenly divided the talar dome into a 3 × 3
grid, then reviewed 428 ankle MRIs of patients
with talar osteochondral lesions and classified
the lesions accordingly.
• They found that the midmedial zone was the
most common location (53%), and these lesions
were the largest and deepest as well. The
second most common zone was the midlateral
zone (26%)
ETIOLOGY
• Acute trauma [History of trauma is documented in more than 85%
cases (98% Lateral lesions and 70% of medial lesions)]. and chronic
microtrauma
• Local osteonecrosis
• Systemic vasculopathies
• Endocrine or Metabolic
• Degenerative joint disease.
• Genetic predisposition
MEDIAL LESSION LATERAL LESSION
• MOI-Inversion and Strong • MOI-Inversion plantarflexion and
dorsiflexion lateral rotation of the tibia on
the talus
• More posterior ,deeper and cup • More anterior , shallow and
shaped wafer shaped
• Usually non displaced and more • Usually displaced and less
common common than medial lession
 DIAGNOSIS
• Chronic ankle pain(associated trauma such as inversion injury to
lateral ligamentous complex)
• Chronic lateral ankle pain and chronic ankle sprain pain.
• Persistant ankle swelling, weakness ,giving away or mechanical
symptoms ( catching, clicking, locking)
Stages
They classified the “lesion” into four different
stages according to plain radiographs:
• Stage I - A small area of compression of
subchondral bone
• stage II -A partially detached osteochondral
fragment
• Stage III - A completely detached
osteochondral fragment remaining in the
crater
• Stage IV -A displaced osteochondral
fragment
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