Biomechanics of ankle_jointPresentation Transcript
Biomechanics of ankle joint
• The ankle-foot complex is structurally
analogues to the wrist-hand complex of the
• The ankle-foot complex must meet the
stability and mobility demands.
1.Providing a stable base of support for the
body in a variety of weight bearing postures
without undue muscular activity and energy
2.Acting as a lever for effective push-off during
1.Dampening of rotations imposed by more
proximal joints of LL.
2.Being flexible enough as a shock absorber
3.Permitting the foot to conform to the changing
and varied terrain on which foot is placed.
• The ankle and foot meet its requirements through
• 28 bones
• 25 joints.
proximal and distal tibiofibular joints
Talo-crural or ankle joint
Talocalcaneal or subtalar joint
5 tarso-metatarsal joints
5 metatarso-phalangeal joints
9 inter-phalangeal joints
• The bones of the foot are traditionally divided
into 3 functional segments.
• HIND FOOT-posterior segment
composed of talus and calcaneus
• MID FOOT-middle segment
composed of navicular,cuboid, 3 cuneiforms
• FOREFOOT-anterior segment
composed of metatarsals and phalanges.
The term ankle specifically refers to :
• Talocrural joint-The formation of the mortise
(a hole) by the medial malleoli (Tibia) and
lateral malleoli (fibula) with the talus lying
in between them makes up the talocrural
• The ankle is a synovial Hinge joint with
joint capsule and associated ligaments.
• It is generally considered to have a single
oblique axis with 1°of freedom.
PROXIMAL ARTICULAR STRUCTURE
• The proximal segment of ankle is composed of
concave surface of distal tibia and of tibial and
• The structure of distal tibia and the two
malleoli is referred to as a MORITSE.
• The mortise of the ankle is adjustable, relying
on the proximal and distal tibio-fibular joints.
PROXIMAL TIBIO-FIBULAR JOINT
• It is a plane synovial joint formed by
articulation of head of fibula with the postero-
lateral aspect of tibia.
• Although facets are flat, a slight convexity of
tibial facet and slight concavity of fibula is
• Each proximal tibiofibular joint is surrounded
by a joint capsule that is reinforced by
anterior and posterior tibiofibular ligaments.
DISTAL TIBIOFIBULAR JOINT
• It is a syndesmosis or fibrous union.
• It is in between the concave facet of tibia and
convex facet of fibula.
• Tibia and fibula do not come into contact with
each other at this point but are separated by
• The ligaments of distal tibio-fibular joint are
primarily responsible for maintaining a stable
It is also called as Anterior tibio-talar
Attached to the anterior part of medial surface
• Lateral ligament
It consists of 3 bands
Anterior talofibular ligament
Posterior talofibular ligament
Posterior tibio-fibular >
<Ant talo fibular
<Sub talar joint space
Ankle joint function
• The primary ankle motion of dorsi-flexion
and plantar-flexion occurs around an
oblique axis that causes the foot to move
across all 3 planes.
• In neutral position of the ankle, the joint
axis passes approximately through the
fibular malleolus and the body of the talus
and through or just below the tibial
malleolus and posteriorly.
• The distal tibia is twisted laterally compared
with its proximal portion accounting for toe-out
position of the foot in normal standing.
• The axis of angle is considered to be rotated
laterally 20°-30° in the transverse plane and
inclined 10° down on the lateral side.
• The shape of the body of talus is complex.
• The trochlea is wider anteriorly than
• The lateral (fibular) facet is substantially larger
than the medial (tibial) facet and its surface is
oriented slightly obliquely to that of medial
• This resembles a truncated cone.
• This causes greater displacement of fibular
malleolus on lateral facet of talus than the
tibial on medial facet.
• The greater excursion of the lateral malleollus
results in the imposition of motion on the fibula
in several directions through the ankle ROM.
• This motion is found to be small in magnitude
and variable in direction among individuals and
with different loading conditions.
• This is related to the orientation of the proximal
tibiofibular facet,with more mobility available in
those facets that are more vertical.
• It may depend on the tibiofibular ligamentous
close to extensor
part of this muscle)
(deep to ext.
NOTE: Muscles pass
to the medial side of
• The talocalcaneal or subtalar joint is a
composite joint formed by three separate plane
articulations between the talus superiorly and
• Provides a triplanar movement around a single
posterior talocalcaneal articulations-Largest
concave facet-undersurface of body of talus
convex facet- calcaneus
• Anterior and medial talocalcaneal articulations
Convex facet- Inferior body and neck of talus
• Between the posterior articulation and
anterior,middle articulation a bony tunnel is
present formed by a sulcus(concave groove) in
the inferior talus and superior calcaneus.
• This funnel shaped tunnel is called TARSAL
• TARSAL CANAL
Larger end- SINUS TARSI-lies anterior to fibular
smaller end- lies posterior to the tibial
And above a bony out cropping on calcaneus is
called SUSTENTACULUM TALI
Posterior articulation has its own capsule
Anterior and middle articulations share a
capsule with the talonavicular joint.
Cervical ligament- strongest
Interosseus talocalcaneal ligament
lateral talocalcaneal lig
Inferior extensor retinaculum –provides subtalar
• Allow pronation/supination
• The talus articulates with
the calcaneus anteriorly,
posteriorly and medially.
• The axis of rotation runs
diagonally from the
posterior, lateral, plantar
surface to the anterior,
medial, dorsal surface.
• The orientation of this axis
triplanar with reference to
the cardinal planes.
Tibial Rotation• The subtalar joint can be
likened to the action of a
mitered hinge (Inman and
• The orientation of the
subtalar joint axis causes
the tibia to internally rotate
during pronation and
externally rotate during
• Thus, the tibia internally
rotates with pronation or
knee flexion and externally
rotates with supination or
It is important that
knee flexion and
pronation occur in
well as knee-extension
• CLOSED PACKED POSITION-
• POSITION OF RELATIVE MOBILITY –
Transverse tarsal joint
• The transverse tarsal joint, also called the
midtarsal or Chopart joint
It is a compound joint formed by the
talonavicular and calcaneocuboid joints .
• The two joints together present an S-
shaped joint line that transects the foot
horizontally, dividing the hindfoot from the
midfoot and forefoot.
• The navicular and the cuboid bones are
considered, immobile in the weight-bearing
• Talonavicular joint
• The proximal portion of the talonavicular
articulation is formed by the anterior portion
of the head of the talus, and the distal
portion of the articulation, by the
concave posterior aspect of the navicular
• A single joint capsule encompasses the
talonavicular joint facets and the anterior
and medial facets of the subtalar joint.
• Inferior aspect of the joint capsule-
plantar calcaneo-navicular lig/spring lig
• Medially- deltoid lig
• Laterally-bifurcate lig
• Calcaneo-cuboid joint
• The calcaneo-cuboid joint is formed
proximally by the anterior calcaneus and
distally by the posterior cuboid bone
• The calcaneocuboid articulation has its own
capsule that is reinforced by several
The capsule is reinforced
• Laterally - lateral band of the bifurcate
ligament (also known as the calcaneocuboid
• Dorsally –dorsal calcaneocuboid ligament,
• Inferiorly -plantar calcaneocuboid (short
plantar) and the long plantar ligaments
Actually consists of two joints: the
calcaneocuboid on the lateral side
and the talonavicular on the medial
the axes of these
two joints are
parallel, this unlocks
the joint and creates
a hypermobile foot
that can absorb
During supination the
axes are not parallel
and this joint
Tarsal transverse joint axis
• The transverse joint is considered to have two
axis around which the talus and calcaneus
moves on the relatively fixed naviculo-cubiod
• Motion around this axis is triplanar
producing supinaion /pronation with
coupled components similar to those seen in
• It approaches a true A-P axis producing
inversion and eversion component
The longitudinal axis of the transverse
Inclined 15° superiorly from the transverse plane
Inclined 9° medially
from the sagittal plane.
• Oblique axis
• This triplanar axis also provides
supination/pronation with coupled component
movements of the talus and calcaneus segments
moving together on the navicular and cuboid
• The dorsiflexion/plantarflexion and
abduction/adduction components predominate
• Motions about the longitudinal and oblique axes
are difficult to separate and quantify.
The oblique axis of the
Inclined 57° from the
superiorly from the transverse plane.
TRANSVERSE TARSAL JOINT
• Any weight-bearing subtalar motion
includes talar abduction/adduction-
dorsiflexion/plantarflexion that also causes
motion at the talonavicular joint
• calcaneal inversion/eversion that causes
motion at the calcaneocuboid joint.
• As the subtalar joint supinates, its linkage
to the transverse tarsal joint causes both
the talonavicular joint and the
calcaneocuboid joint to begin to supinate
also.(CLOSE PACKED POSITION)
• When the subtalar joint is pronated and
loose-packed, the transverse tarsal joint is
also mobile and LOOSE PACKED .
• The transverse tarsal joint is the
transitional link between the hindfoot and
the forefoot, serving to
(1)add to the supination/pronation range of
the subtalar joint and
(2) compensate the forefoot for hindfoot
• Weight-Bearing Hindfoot Pronation and
Transverse Tarsal Joint Motion
In the weight-bearing position, medial rotation
of the tibia
for example-pivoting on a fixed foot
• Weight-Bearing Hindfoot Supination and
Transverse Tarsal Joint Motion
• A lateral rotatory force on the leg will create
• subtalar supination in the weight-bearing
subtalar joint with a relative pronation of the
transverse tarsal joint (opposite motion of the
forefoot segment) to maintain appropriate
weight-bearing on a level surface Supination
of the subtalar joint, however, can proceed
to only a certain point before the transverse
tarsal joint also begins to supinate.
With pronation occurring at the subtalar joint through medial rotation
of the leg, the transverse tarsal joint is free to
(A) supinate slightly to maintain the relatively fixed position of the
forefoot segment; (B) pronate slightly as occurs in normal
(C)supinate substantially to maintain appropriate weight-bearing of
the forefoot segment on uneven terrain
With supination occurring at the subtalar joint through lateral
rotation of the leg, the transverse tarsal joint has limited ability to
pronate to maintain the relatively fixed position of the forefoot
(A); will begin to supinate with a greater range of
subtalarsupination and lateral rotation of the leg (B); or will fully
supinate along with a fully supinated subtalar joint and maximal
lateral rotation of the superimposed leg (C).
JOINTS• The tarsometatarsal TMT joints are plane
synovial joints formed by the distal row of tarsal
bones (posteriorly) and the bases of the
Deep transverse metatarsal ligament
• This spans the heads of the metatarsals on the
plantar surface and is similar to that found in
• Contribute to stability of proximal located TMT
joints by preventing excessive motion and
splaying of metatarsal heads.
• A ray is defined as a functional unit formed
by a metatarsal and (for the first through
third rays) its associated cuneiform bone.
• The cuneiform bones are included as parts
of the movement units of the TMT rays
because of the small and relatively
insignificant amount of motion occuring at
the cuneonavicular joints.
• The axis of the first ray is inclined in such as
way that dorsiflexion of the first ray also
includes inversion and adduction, whereas
plantarflexion is accompanied by eversion and
• The abduction/adduction components normally
• Movements of the fifth ray around its axis are
more restricted and occur with the opposite
arrangement of components.
• Dorsiflexion is accompanied by eversion and
abduction, and plantarflexion is accompanied
by inversion and adduction.
• The axis for the third ray nearly coincides
with a coronal axis; the predominant
motion, therefore, is
• The axes for the second and fourth rays
were not determined
• In weightbearing,the TMT joints function
primarily to augment the function of the
transverse tarsal joint; that is, the TMT
joints attempt to regulate position of the
metatarsals and phalanges (the forefoot) in
relation to the weight-bearing surface.
• SUPINATION TWIST
• When the hind foot pronates substantially in
• The TTJ Joint counter acts the forefoot to
keep the plantar aspect of the foot in contact
with the ground.
• TMT –medial forefoor will press the ground
lateral foot will lift off the ground
1st and 2nd ray -dorsiflexion
4th and 5th ray-plantarflexion
• the entire forefoot undergoes an inversion
rotation around a hypothetical axis at the
• PRONATION TWIST
• When the hind foot and TTJ are locked in
supination ,the adjustment of forefoot position
will be left entirely to TMT Joints.
• TMT-forefoot medial –lift off the ground
• lateral-press to the ground
1st and 2nd-plantarflex
4th and 5th –dorsiflexion
• Eversion accompanies
• Needed for traction between the floor & foot’s wt bearing
• Tensed throughout stance phase.
• Compared to a tie rod.
• Plantar plates of mtp resist compressive & tensile forces
transferred through plantar aponeurosis.
• In toe extension- mt heads act as pulleys that pull this fascia–
Movement GRF Contracti
– foot flat
Neutral 15 deg PF PF Pronation Eccentric Dorsiflexo
15 deg PF 5-10 deg
Midstance 5-10 deg
Neutral Flexion Anterior concentric PF
Heel off to
Neutral 20 deg PF PF Anterior Concentric PF
20 deg Pf Neutral DF NO Concentric DF