applied gait definitions / ankle

huffaker

Stride

Occurs from the time the heel touches the floor until that same heel touches the floor again

Stride Length

is the distance travelled during the gait cycle

Step

is one half of a stride - it takes two steps to complete a gait cycle

Step Length

is the distance between the heel strike of one foot and the heel strike of the other foot

Cadence

walking speed or the number of steps per minute

Two phases of gait

Stance= time the limb is in contact with the ground (60%)

Swing= time the limb is off the ground (40%)

Initial Contact

The moment the foot touches the ground

Loading Response

Body weight is transferred to the extended limb (first period of double limb support) foot is lowered to the floor

Mid stance

body weight progress over a single, stable limb

Terminal stance

body weight moves ahead of the limb and weight is transferred to the forefoot

Pre swing

Body weight is transferred to the contralateral limb (second period of the double limb support) knee flexes rapidly

initial swing

the thigh begins to advance as the foot comes off the ground

Mid swing

the thigh continues to advancem kknee begins to extend and the foot clears the ground

terminal swing

the knee extends, the limb prepares to make contact with the ground

weight acceptance

Includes IC and LR

body weight is rapidly loaded onto the extended limb. both feet are in contact with the ground.

Single limb support

Includes MSt and TSt

body weight progresses over a single stable limb

Swing limb advancement

Includes PSw, ISw, MSw, TSw

Body weight is unloaded and the foot comes off the ground. limb is moved from behind the body to in front of the body.

Critical events

specific joints positions or motions contribute to the accomplishment of functional tasks. each phase has one or more critical events at the ankle, knee or hip in the saggital plane

Torque demands- early mid stance

vector falls anterior to the ankle joint - to prevent excessive dorsiflexion, calf muscles need to contract eccentrically.

Vector is posterior to the knee joint - to prevent excessive knee flexion, the quads contract eccentrically

Torque demands- late mid stance

vector falls anterior to the knee joint which causes extension so no muscle activity needed

Ankle- initial contact ROM

Neutral

Ankle- initial contact TD

ground contact posterior to the ankle joint creates a plantar flexion torque

Ankle- initial contact MA

pretibial muscles - eccentric contraction

Ankle- initial contact FS

foot is positioned for the heel rocker action at loading response

Ankle- Loading response ROM

5 degrees of plantar flexion

Ankle- Loading response TD

plantar flexion torque forces the foot to the floor and then diminishes

Ankle- Loading response MA

pretibials contract eccentrically in reaction to PF torque. Soleus and gastroc become active late to control tibial advancement - eccentric contraction

Ankle- Loading response FS

heel rocker action

heel rocker

creates forward momentum

Ankle- mid stance ROM

dorsiflexion to 5 degrees (passive)

Ankle- mid stance TD

increasing dorsiflexion torque

Ankle- mid stance MA

soleus and gastroc control forward progression of the tibia- eccentric

Ankle- mid stance FS

body progresses over a stable foot and tibia

ankle rocker

Ankle rocker

advances the tibia over the stationary foot

Ankle - terminal stance TD

dorsiflexion to 10 degrees (passive)

Toes - MTP joint extend to 30 degrees

Ankle - terminal stance TD

dorsiflexion torque reaches a peak

Ankle - terminal stance MA

calf muscle concentric activity peaks and prevents forward tibial collapse and to allow the heel to rise

Ankle - terminal stance FS

forefoot rocker

Forefoot rocker

during terminal stance, the heel rises and toes extends

Ankle - pre swing ROM

15 degrees of plantar flexion

MTP joints extend to 60 degrees

Ankle - pre swing TD

dorsiflexion torque decreases

Ankle - pre swing MA

calf muscle activity ceases, pretibial muscles begin to contract concentrically in preparation for dorsiflexion

Ankle - pre swing FS

forefoot remains on the floor for balance. plantar flexion assists with knee flexion

Ankle - initial swing ROM

5 degrees of plantar flexion

Ankle - initial swing TD

minimal plantar flexion torque

Ankle - initial swing MA

pretibials concentrically initiate dorsiflexion

Ankle - initial swing FS

dorsiflexion begins to clear the foot from the ground

Ankle - mid swing ROM

dorsiflexes to neutral

Ankle - mid swing TD

minimal plantar flexion troque

Ankle - mid swing MA

pretibials - isometric contraction

Ankle - mid swing FS

foot clears the ground

Ankle - terminal swing ROM

neutral

Ankle - terminal swing TD

zero

Ankle - terminal swing MA

pretibials isometrically contract

Ankle - terminal swing FS

neutral position prepares for initial contact

Subtalar joint

articulation between the talus and the calcaneus

Subtalar joint closed-chain

in the right subtalar joint

the talus is mobile while the forefoot is fixed by its contact with the ground

Subtalar joint - initial contact

the foot is supinated.

Subtalar joint - loading response

the calcaneus everts to 5 degrees and the foot pronates

pronation assists in shock absorption

Subtalar joint - terminal stance

decrease in eversion

reduction in eversion increase stability and promotes forefoot rocker

Subtalar joint - pre swing

foot supinates for push off

swing phases, remains supinated

Toes - terminal stance

passive MTP extension to 30 degrees

Toes - pre swing

passive MTP extension to 60 degrees

extensor hallucis longus and extensor digitorum begin to contract for push off

Toes - initial swing

extensor hallucis longus and extensor digitorum at peak activity