Transcript Ankle Structure

lateral
Talocrural joint
• inferior tibiofibular
jnt.
• tibiotalar jnt.
Subtalar joint
• aka talocalcaneal
• between talus and
calcaneus
Midtarsal joint
• between calcaneus and
cuboid on lateral side
medial
• between talus and
navicular on the medial
side
Talocrural Joint
• Articulation between the tibia and fibula
(inferior tibiofibular joint) and between the
tibia and the talus (tibiotalar joint).
• This joint is responsible for plantar flexion
and dorsiflexion and some
abduction/adduction.
• The axis of rotation is a line between the
two malleoli.
Subtalar Joint
• Allows pronation/supination
and rotation.
• 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
makes pronation/supination
triplanar with reference to the
cardinal planes.
Pronation/Supination
Open Chain
calcaneus
moves on
talus
Closed Chain
talus moves
on calcaneus
Pronation
Supination
calcaneal eversion
abduction
dorsiflexion
calcaneal inversion
adduction
plantar flexion
calcaneal eversion
talar adduction
plantar flexion
calcaneal inversion
talar abduction
dorsiflexion
Tibial Rotation
It is important that knee flexion
and pronation occur in
synchronization (as well as
knee extension and supination).
• The subtalar joint can be
likened to the action of a
mitered hinge (Inman and
Mann, 1973).
• The orientation of the subtalar
joint axis causes the tibia to
internally rotate during
pronation and externally rotate
during supination.
• Thus, the tibia internally rotates
with pronation or knee flexion
and externally rotates with
supination or knee extension.
Midtarsal Joint
Actually consists of two joints: the
calcaneocuboid on the lateral side and the
talonavicular on the medial side.
During pronation, the
axes of these two joints
are parallel, this
unlocks the joint and
creates a hypermobile
foot that can absorb
shock. During
supination the axes are
not parallel and this
joint becomes locked
allowing efficient
transmission of forces.
Foot Orientation
A forefoot valgus exists
when the forefoot is everted
relative the rearfoot. This
is not as common as
forefoot varus.
A forefoot varus exists
when the forefoot is
inverted to the rearfoot.
This is the most common
cause of excessive
pronation.
A rearfoot valgus exists
when the rearfoot is
everted.
A rearfoot varus exists
when the rearfoot is
inverted. This can increase
maximum pronation.
Ligaments
Lateral side of ankle accounts for 85% of ankle sprains
Arches of the Foot
Fascia
Plantar surface
There are 3 arches in the foot that contribute to support and shock
absorption. These arches are maintained by the shape of the tarsal
and metatarsal bones, ligaments and plantar fascia.
Arch Types
• Feet are often classified according to the
height of the medial arch.
– Normal
– high-arched or pes cavus
– flat-footed or pes planus
• Arches can also be rigid or flexible.
• High-arched, rigid feet make poor shock
absorbers.
• Flat-footed, flexible arches often allow
excessive pronation.
Plantar Flexors
Gastrocnemius
NOTE:
1) Soleus lies
deep to
gastrocnemius
2) Both insert into
the calcaneal
tendon aka
Achilles tendon
Posterior View
Soleus
Assistant
Plantar Flexors
Tibialis Peroneus
Posterior Brevis
Peroneus
Longus
Note: Their tendons pass
posteriorly to the malleoli
Flexor
Flexor
Digitorum Hallucis
Longus Longus
Plantaris
Note:
insertion
is wrong!
Dorsiflexion
tibialis
anterior
extensor
digitorum
longus
peroneus tertius
(usually very
close to extensor
digitorum longus
and often
considered as
part of this muscle)
extensor
hallucis
longus
(deep to ext.
digitorum
longus)
Invertors
primary
tibialis
anterior
tibialis
posterior
extensor
hallucis
longus
NOTE: Muscles pass
to the medial side of
the foot!
flexor
flexor
digitorum hallucis
longus longus
Evertors
primary
peroneus
brevis
peroneus
longus
peroneus
tertius
extensor
digitorum
longus
Causes of Excessive Pronation
•
•
•
•
•
•
•
Q-angle greater than 20 degrees
tibial varus greater than 5 degrees
rearfoot varus greater than 2 degrees
forefoot varus greater than 3 degrees
plantar flexed first ray
weak medial arch
tight gastrocnemius and soleus or a short Achilles
tendon
The Problem with
Excessive Pronation
Excessive or prolonged pronation during the support
phase will disrupt the normal tibial-femoral rotation
relationship at the knee. The tibia continues to
internally rotate with the prolonged pronation while
the knee is extending. Knee extension is normally
associated with external tibial rotation.