Biomechanics of foot

BIOMECHANICS OF FOOT
PRAKASH SAHOO
MPO 1ST YEAR

INTRODUCTION
• Leonardo da Vinci said, "The human foot is a
masterpiece of engineering and a work of art."
• The foot is a key element in aligning the joints
of the lower limb to achieve a normal gait
pattern.
• The complementing structures of the
ankle/foot complex permit both stability and
mobility depending on conditions acting on it.

• The foot is able to sustain large weight-bearing
stresses while accommodating to a variety of
surfaces and activities.
• The foot must be stable to provide an adequate
base of support and function as a rigid lever for
pushing-off when walking, running, or jumping.
• The foot must also be mobile to adapt to uneven
terrain, absorb shock as the foot hits the ground,

Anatomy
Anatomically and
biomechanically, the foot is
often subdivided into:
• The rearfoot or hindfoot (the
talus and calcaneus)
• The midfoot (the navicular,
cuboid and the 3 cuneiforms)
• The forefoot (the 14 bones of
the toes, the 5 metatarsals)

Joints of the foot
• Subtalar joint-
• The talocalcaneal, or subtalar,
joint is a composite joint
formed by three separate
plane articulations between
the talus superiorly and the
calcaneus inferiorly.

• Ligaments-
• The subtalar joint is a stable joint that is rarely
dislocated. It has a congruent osseous
anatomy as well as strong ligamentous
support.
• The subtalar joint receives support from the
ligamentous structures that support the ankle,
as well as from ligamentous structures that
only cross the subtalar joint.

• These included, from superficial to deep, the
calcaneofibular, posterior talocalcaneal,posterior
talofibular and interosseous talocalcaneal ligaments.

• Axis of the subtalar joint inclined up from the
transverse plane approximately 42° and inclined
medially from an A-P axis approximately 16°.

TRANSVERSE TARSAL JOINT
• The transverse tarsal joint, also called the
midtarsal or Chopart joint, 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.

TALO-NAVUCULAR CALCANEO-
CUBOID

• 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
bone.

• Calcaneocuboid Joint-
• The calcaneocuboid joint is formed proximally
by the anterior calcaneus and distally by the
posterior cuboid bone .
• The articular surfaces of both the calcaneus
and the cuboid bone are complex, being
reciprocally concave/convex both side to side
and top to bottom.

Transverse Tarsal Joint Axes
• The longitudinal axis of the transverse tarsal
joint is inclined 15° superiorly from the
transverse plane and inclined 9° medially from
the sagittal plane.
• The oblique axis of the transverse tarsal joint
is inclined 57° from the sagittal plane and
inclined 52° superiorly from the transverse
plane.

• Transverse Tarsal Joint Axes-

TARSOMETATARSAL JOINTS
• The tarsometatarsal (TMT)
joints are plane synovial joints
formed by the distal row of tarsal
bones (posteriorly) and the
bases of the metatarsals.
• The first (medial) tarsometatarsal
joint is composed of the
articulation between the base of
the first metatarsal and the
medial cuneiform bone.

• The second tarsometatarsal joint
is composed of the articulation
of the base of the second
metatarsal with a mortise
formed by the middle cuneiform
bone and the sides of the medial
and lateral cuneiform bones.
• This joint is set more posteriorly
than the other tarsometatarsal
joints; it is stronger and its
motion is more restricted.

• The third tarsometatarsal joint,
formed by the third metatarsal
and the lateral cuneiform.
• The bases of the fourth and fifth
metatarsals, with the distal
surface of the cuboid bone, form
the fourth and fifth
tarsometatarsal joints.

Tarsometatarsal Joint Function
• The greatest relevance of tarsometatarsal joint
motions is found during weight-bearing.
• In weight-bearing, the tarsometatarsal joints
function primarily to augment the function of
the transverse tarsal joint.
• That is, the tarsometatarsal joints attempt to
regulate position of the metatarsals and
phalanges (the forefoot) in relation to the
weight-bearing surface.

• Pronation
– The three body plane motions in pronation are
abduction in the transverse plane, dorsiflexion in
the sagittal plane, and eversion in the frontal
plane .
• Supination
– The three body plane motions in supination are a
combined movement of adduction,
plantarflexion, and inversion.

Supination Twist
• When the hind foot pronates substantially in
weight bearing, the transverse tarsal joint
generally will supinate to some degree to counter
rotate the forefoot and keep the plantar aspect of
the foot in contact with the ground.
• If the range of transverse tarsal supination is not
sufficient to meet the demands of the pronating
hind foot then the medial forefoot will press into
the ground, and the lateral forefoot will tend to
lift.

• The first and second rays will be pushed into
dorsiflexion by the ground reaction force, and the
muscles controlling the fourth and fifth rays will
plantar flex those tarsometatarsal joints in an
attempt to maintain contact with the ground.
• Both dorsiflexion of the first and second rays and
plantarflexion of the fourth and fifth rays include
the component motion of inversion of the ray.

• Consequently, the entire forefoot (each ray
and its associated toe) undergoes an inversion
rotation.
• This rotation is referred to as supination twist
of the tarsometatarsal joints.

Pronation Twist
• With hindfoot supination, the forefoot tends
to lift off the ground on its medial side and
press into the ground on its lateral side.
• The muscles controlling the first and second
rays will plantarflex those rays in order to
maintain contact with the ground, whereas
the fourth and fifth rays are forced into
dorsiflexion by the ground reaction force.

• Because eversion accompanies
both plantarflexion of the first
and second rays and dorsiflexion
of the fourth and fifth rays, the
forefoot as a whole undergoes a
pronation twist.

METATARSOPHALANGEAL JOINTS
• The five metatarsophalangeal (MTP)
joints are condyloid synovial joints
with two degrees of freedom:
• extension/flexion (or
dorsiflexion/plantarflexion) and
• abduction/adduction.

• The metatarsophalangeal joints are formed
proximally by the convex heads of the
metatarsals and distally by the concave bases
of the proximal phalanges.
• Metatarsophalangeal motions can occur in
weight-bearing or non-weight bearing, the
metatarsophalangeal joints serve primarily to
allow the weight-bearing foot to rotate over
the toes through metatarsophalangeal
extension (known as the metatarsal break)
when rising on the toes or during walking.

• The metatarsal break derives its name
from the hinge or “break” that occurs at
the metatarsophalangeal joints as the
heel rises and the metatarsal heads and
toes remain weight bearing.
• The metatarsal break occurs as
metatarsophalangeal extension around
a single oblique axis that lies through
the second to fifth metatarsal heads.

• The metatarsal break occurs
around an oblique axis that
passes through the heads of
the four lesser toes, at an angle
to the long axis of the foot that
varies widely among individuals
from 54° to 73°.
54-73 deg

INTERPHALANGEAL JOINTS
• The interphalangeal (IP) joints of the toes are
synovial hinge joints with one degree of
freedom: flexion/extension.
• The great toe has only one interphalangeal
joint connecting two phalanges, whereas the
four lesser toes have two interphalangeal
joints (proximal and distal interphalangeal
joints) connecting three phalanges.

Biomechanics of foot

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