Foot Mechanics 2

What happens during 0-30% [heel strike to mid stance] in gait?

Ankle eversion to INCREASE pliability

• Shock absorption

• Calcaneus in valgus/eversion

Medial arch drops to open pack position to make more flexible.

• Initiates pronation

Heel strike

• Slight ER of hip

• Talocrural: dorsiflex

• Subtalar: inversion

Initiation of knee flex = Tibial IR

What happens during 30-51% gait [midstance to heel off]?

Ankle inversion to INCREASE STABILITY

• For toe off

• Closed pack position [rigid]

• Increase medial arch

Hip influences ankle

Near push-off: hip ER

• Windlass mechanism

Calcaneus moves to VARUS, supinates

3 Joints involved in supination/pronation

Subtalar

Talocrural

Transverse tarsal joints

• Therefore it is a triplanar movement!

What axis does dorsi/plantarflexion occur?

ML

What axis does eversion/inversion occur?

AP axis

What axis does abduction/adduction occur?

Vertical axis

What axis does pronation/supination occur in?

Oblique axis

Triplanar movement

What motion does talocrural joint do?

Dorsiflex + plantar

Dorsi= closed pack. Tightness of ligaments

• Tibia wedged in talus

  • Talus wider anteriorly

• More congruent, rigid, stable

• Better fit

What contributes to ankle stability?

Soft tissue

Ligaments

Mm

Action of subtalar joint

Btwn talus and calcaneus. A.k.a rearfoot

3 separate facets (anterior, posterior and middle facets)

Larger posterior

• May be mobilized

Contributes to ab/dduction

Lateral side rotates into inversion

Oblique axis of rotation

Transverse tarsal joint action + make up

Btwn talus + navicular

Calcaneus and cuboid

Contributes to…

• inversion/eversion

• plantar + dorsiflexio n

a.k.a. Midfoot [intertarasals + transverse tarsal]

Supination actions

Plantarflex

INversion

Adduct

Calcaneus moves into varus (inversion @ subtalar)

Push medially to go forward

Pronation actions

Calcaneus moves valgus (@ subtalar joint)

Dorsiflex

Evert

ABduct

Axis of rotation of talocrual joint in pro/supination?

Not paralel w/ ML axis

Actions the talocrural joint contribute to pronation/supination?

Pronation: Dorsiflexion

Supination: Plantarflexion

• Add/duction + evert/invert

Axis of rotation of subtalar joint in pro/supination?

Not aligned w/ plantar surface/AP

Longitudinal axis

Actions the subtalar joint contribute to pronation/supination?

Pronation: eversion + abduction

Supination: Inversion + adduction

Axis of rotation of transverse tarsal joint in pro/supination?

Abduction/adduction: vertical axis

Eversion/inversion: oblique AP axis

Dorsi/plantarflexion: ML axis

Actions the transverse tarsal joint contribute to pronation/supination?

Pronation: Eversion

Supination: Inversion

Do superior structures influence the foot + ankle?

YES, tibial + femoral rotation influences

• Both IR during heel strike - mid stance

• Both ER from mid-stance to toe off

What way does tibia rotate during supination/pronation?

Pronation: Tibial IR

Supination: Tibial ER

• Medial arch increases

Mm action in early stance [heel strike] - load acceptance

Initial PF controlled by dorsiflexors eccentrically

Accept weight; lower medial arch → pronation begins

• Controlled by invertors eccentrically

Open pack position

Mm action in Late stance → heel off

Leg ER to change from eversion → inversion

Raise arch as weight lifted due to tib post and intrinsics

Inverts + PF

Mm action in heel off → toe off

Requires supination

Co-activation of intrinsic/extrinsic + windlass mechanism

Increase stability for pivot

Foot malalignment/excessive sup/pronation

If it ain’t broke, don’t fix it!

Not always bad because normal process during gait

• Maybe okay to decrease pain in the meantime

Running barefoot bad → back then earth was soft

Pes cavus

High arch

Supinator

Pes planus

Flat arch

Pronator

Are over the counter treatments for foot issues effective?

Could have higher-up influences from hip

Tibial rotation from knee movement and ankle/foot movement

Knee extension → tibial ER → supination

Knee lfexion →