Biomechanics of

Ankle and Foot

Ankle Joint

Tibia and Fibula

Talus

Bone Anatomy Ankle Mortise

Leg Tibia

Weak point - distal 1/3

Fibula Attached to tibia

via interosseus membrane

Talus

Tibia-Fibula Fixation

Interosseous Membrane

Distal Tibiofibular Ligament Anterior Posterior

Function of Lower Leg

Lower leg provides Support for the entire body Propulsion through space Adaptation to uneven terrain Absorption of shock

Ankle Ligaments

Lateral Medial

1

Lateral Ankle Liagaments

3 primary Lateral ankle ligamentsAnterior talofibularPosterior talofibularCalcaneofibular

Support and maintenance of bone apposition

Prevent inversion of the foot associated with plantar flexion

Lateral ankle Liagaments

Medial Ankle Liagaments Triangular in shape with two smaller

ligaments beneath Usually called Deltoid Ligament Runs from the medial malleolus of the

tibia to the talus, and the navicular bone Anterior Tibiotalar part Posterior Tibiotalar part Tibiocalcaneal part Tibionavicular part

Medial Ankle Liagaments

Provide a great deal of stability to the medial side of the ankle

Prevent eversion of the foot associated with dorsiflexion

Rarely injured in sports

Medial Ankle Ligament

Joints of Ankle

Tibiofibular joint Amphiarthrodial joint Space in-between is called the mortise

Talocrural joint or Ankle joint Modifies hinge joint formed by the tibia,

lateral malleolus of the fibula, and the talus

Movements

Dorsiflexion

Raising the toes

Plantarflexion

Point the toes

Ankle Goniometry

Dorsiflexion0-25 degrees

Plantarflexion0-50 degrees

Normal gait requires 10 degrees of dorsiflexion and 20 degrees of plantar flexion with the knee fully extended

Joint reaction force in stance is 4 times BW

Muscles

Anterior compartment Posterior compartment

Deep group superficial group

Lateral compartment

Anterior compartment

Tibialis anterior Extensor digitorum Extensor hallucis longus

Extensor Extensor Digitorum Digitorum

LongusLongus

Extensor Extensor Hallicus Hallicus LongusLongus

Tibialis Tibialis AnteriorAnterior

Posterior compartment

Superficial groupGastrocnemiusSoleusPlantaris

GastrocGastroc SoleusSoleus PlantarisPlantaris

Posterior compartment

Deep groupTibialis posteriorFlexor digitorum longusFlexor hallucis longus

Flexor Digitorum Flexor Digitorum LongusLongus

Flexor Hallicus Flexor Hallicus LongusLongus

Tibialis Tibialis PosteriorPosterior

Lateral compartment

Peroneus longus Peroneus brevis Peroneous tertius

Peroneus LongusPeroneus Longus Peroneus BrevisPeroneus BrevisPeroneus Peroneus TertiusTertius

Foot

Foot Serves as

A base of support provides a stable platform A shock absorber A mobile adapter generates propulsion A rigid lever at push-off

Divided into 3 parts Hind foot Midfoot Forefoot

Hindfoot

Talus

Hindfoot

Calcaneous

Midfoot

Navicular Bridges movements between the hindfoot

and forefoot

Cuboid 1st, 2nd, 3rd Cuneiforms

Forefoot

5 metatarsals 14 phalanges Work together to form arches which

distribute body weight throughout the foot

Phalanges (14)

Metatarsals (5)

Joint of Hindfoot

Subtalar joint articulation between talus and calcaneus classified as gliding joint Converts tibial rotation to forefoot supination

and pronation

Subtalar Axis

Subtalar Axis

Triplanar/oblique (Up, forward and medial) Inclined up approximately 420

Inclined medially approximately 160

Movements of Subtalar Joint

Supination Adduction Inversion Plantarflexion

Pronation Abduction Eversion Dorsiflexion

Ideal Rearfoot Alignment

Forefoot Valgus

Foot Supination

Calcaneus invertsTalus adducts and dorsiflexes

Forefoot Varus

Foot Pronation

Calcaneus everts Talus adducts and flexes

Locking and Unlocking Joint

Joint of Midfoot

Transverse tarsal joint articulation between

talus, navicular, calcaneus and cuboid bones

classified as gliding joint

Movements Forefoot abduction

and adduction

Action of the Transverse Tarsal Joint

Transitional link between the hindfoot and the forefoot

Hindfoot supination provides rigid lever

When hindfoot is supinated, Transverse tarsal joints ability to compensate is restricted

Action of the Transverse Tarsal Joint

When hindfoot is pronated, Transverse tarsal joint can compensate to maximize forefoot contact

Action of the Transverse Tarsal Joint

Tarsometatarsal joints

Medial cuneiform with 1st metarsal bone Intermediate cuneiform with 2nd

metarsal bone Lateral cuneiform with 3rd metarsal

bone Cuboid with 4th and 5th metarsal bone Small gliding joints Allow foot to adapt to uneven surfaces

during gait

Metatarsophalangeal joints

All are condyloid joints Flexion/extension (dorsiflexion and

plantarflexion), Abduction/Adduction More dorsiflexion than plantar to allow

body to pass over MP joints when walking

Interphalangeal joints

Hinge joint Phalanges

work to transition weight from one foot to the other

Arches of Foot

Longitudinal Arch Lateral Longitudinal Arch Medial Longitudinal Arch

Arches of Foot

Transverse Arch

Functions of Arches

Support Shock absorption

Medial Longitudinal Arch Weight transmission

Lateral Longitudinal Arch Increase mobility

Ligamentous Support

Primary supporting ligaments of archs of foot are Calcaneonavicular ligament (spring) Long plantar ligament Plantar fascia (plantar aponeurosis) Short plantar ligament (plantar

calcaneocuboid)

Plantar Fascia

Function of Arches

Support body weight Lever in Pedal arch is dynamic Ligaments active in standing Muscle active in propulsion

Windlass Mechanism

Windlass Mechanism

Classifying Arch Type

Normal Pes Planus: Flat foot Pes Cavus: High Arch

Blood and Nerve Supply of Foot

Muscles of the foot

Intrinsic- muscle has both attachments within the foot

Extrinsis- muscle has one attachment outside of the foot

Extensor Extensor Digitorum Digitorum

LongusLongus

Extensor Extensor Hallicus Hallicus LongusLongus

Tibialis Tibialis AnteriorAnterior

GastrocGastroc SoleusSoleus PlantarisPlantaris

Flexor Digitorum Flexor Digitorum LongusLongus

Flexor Hallicus Flexor Hallicus LongusLongus

Tibialis Tibialis PosteriorPosterior

Peroneus LongusPeroneus Longus Peroneus BrevisPeroneus BrevisPeroneus Peroneus TertiusTertius

Intrinsic Foot Muscles

1st Layer (Superficial) Abductor Hallicus Flexor Digitorum Brevis Abductor Digiti Minimi

2nd Layer Quadratus Plantae Lumbricales

Intrinsic Foot Muscles

3rd Layer Adductor Hallicus Flexor Hallicus Brevis Flexor Digiti Minimi

Intrinsic Foot Muscles

4th Layer Plantar Interosseous Dorsal Interosseous

Intrinsic Foot Muscles

Foot loading

Heel 60% Forefoot 30% Peak forefoot pressure under 2nd MT Footwear helps to distribute pressures

more evenly

Selecting Appropriate Footwear

Footwear should be appropriate for existing structural deformities

For pronators a rigid shoe is recommended

For supinators require more flexible footwear with increased cushioning

Midsole design also set to control motion along medial aspect of foot

Heel counters are also used to control motion in the rearfoot

Other aspects of shoes that may impact foot include outsole contour and composition, lacing systems and forefoot wedges

Selecting Appropriate Footwear