NORMAL GAIT CYCLE Emine CAN HACETTEPE UNIVERSITY- Depatment of Electrical Electronics Engineering

Gait Cycle . P eriod of time from one heel strike to the next heel strike of the same limb

P eriod of time

from

one heel strike

to the next

heel strike of

the same limb

Gait Cycle

Gait Cycle > Time Frame : > > Stance vs. Swing: Stance phase = 6 0 % of gait cycle Swing phase = 40 % > > Single vs. Double support: Single support = 40% of gait cycle Double support = 20%

> Time Frame :

> > Stance vs. Swing:

Stance phase = 6 0 % of gait cycle

Swing phase = 40 %

> > Single vs. Double support:

Single support = 40% of gait cycle

Double support = 20%

STANCE( support ) PERIOD Begins when the heel of the forward limb makes contact with the ground and ends when the toe of the same limb leaves the ground. Foot in contact with the ground

Foot in contact with the ground

SWING ( unsupported ) PERIOD Begins when the foot is no longer in contact with the ground. The limb is free to move. Foot not in contact with the ground

The Tasks of the Gait Cycle Weight acceptance > The transfer of body weight onto a limb that has just finished swinging forward and has an unstable alignment. > Shock absorption and the maintenance of a forward body progression S ingle limb support > One limb support the body weight > Same limb provide truncal stability while bodily progression is continued L imb advancement > Requires foot clearance from the floor > The limb swings through three positions as it travels to its destination in front of the body.

Weight acceptance

> The transfer of body weight onto a limb that has just finished swinging forward and has an unstable alignment.

> Shock absorption and the maintenance of a forward body progression

S ingle limb support

> One limb support the body weight

> Same limb provide truncal stability while bodily progression is continued

L imb advancement

> Requires foot clearance from the floor

> The limb swings through three positions as it travels to its destination in front of the body.

STANCE Subphases IC : Initial Contact (Heel Strike) > Both limbs are in contact – Double stance > The heel strikes the ground > The stance knee begins to flex slightly. > The ankle is at the neutral position > The knee is close to full extension Knee – 0 o Flexion, Tibia externally rotated > Hip 30° of flexion Femur externally rotated > In the sagittal plane, the alignment of the ground-reaction force vector at initial contact is posterior to the ankle joint, creating a plantarflexion moment > Maximum hip flexion occurs during initial contact.

> Both limbs are in contact – Double stance

> The heel strikes the ground > The stance knee begins to flex slightly.

> The ankle is at the neutral position

> The knee is close to full extension Knee – 0 o Flexion, Tibia externally rotated

> Hip 30° of flexion Femur externally rotated

> In the sagittal plane, the alignment of the ground-reaction force vector at initial contact is posterior to the ankle joint, creating a plantarflexion moment

> Maximum hip flexion occurs during initial contact.

STANCE Subphases LR : Loading Response ( Foot Flat ) > Flattening of the foot – reacting to impact of body weigh t > Double stance ends > Knee – 15 o flexion, tibia internally rotates and then begins to externally rotate > Hip – 30 o flexion, femur internally rotating moving to neutral > Maximum Impact Loading occurs > Foot rapidly moves into pronation > Weight has been shifted to the support leg

STANCE Subphases MS: Mid Stance Early Midstance - Late Mid Stance > Single stance > Knee – 15 o flexion, tibia externally rotating > Hip – 25 o flexion, femur internally rotated

> Single stance > Knee – 15 o flexion, tibia externally rotating

> Hip – 25 o flexion, femur internally rotated

STANCE Subphases TS : Terminal Stance ( Heel-off ) > Single stance – “Falling forward” forward fall of the body moves the vector further anterior to the ankle, creating a large dorsiflexion moment > Begins as COG passes over foot and ends when opposite foot touches ground > Knee – 5 o flexion to 0o, tibia externally rotates > Hip – 0 to 10 o extension, femur externally rotates and begins abduction

> Knee – 5 o flexion to 0o, tibia externally rotates

> Hip – 0 to 10 o extension, femur externally rotates and begins abduction

STANCE Subphases PS : Pre-Swing ( Toe-Off/ Knee Break) > Double stance – “Transition” > Limb is rapidly unloaded – “Toe-off” > Knee – 0-30 o flexion, tibia externally rotates > Hip – 20 o extension, femur externally rotates with abduction >The ankle moves rapidly from its dorsiflexion position at terminal stance to 20 degrees of plantarflexion

> Double stance – “Transition” > Limb is rapidly unloaded – “Toe-off”

> Knee – 0-30 o flexion, tibia externally rotates

> Hip – 20 o extension, femur externally rotates with abduction

>The ankle moves rapidly from its dorsiflexion position at

terminal stance to 20 degrees of plantarflexion

SWING Subphases IS : Initial Swing ( acceleration ) > From “toe-off” until maximum knee flexion > Knee – 30–60o flexion, tibia internally rotates > Hip – 0–20o flexion, femur moves from internal rotation to neutral (externally rotating)

> From “toe-off” until maximum knee flexion

> Knee – 30–60o flexion, tibia internally rotates

> Hip – 0–20o flexion, femur moves from

internal rotation to neutral (externally rotating)

SWING Subphases MS : Mid Swing > Goal is for tibia to reach vertical position perpendicular to surface > Knee – moves to 0 o , tibia externally rotates > Hip – 20-30 o flexion, femur externally rotates > Knee extension and hip flexion continue by inertia

> Goal is for tibia to reach vertical position perpendicular to surface

> Knee – moves to 0 o , tibia externally rotates

> Hip – 20-30 o flexion, femur externally rotates

> Knee extension and hip flexion continue by inertia

SWING Subphases TS : Terminal Swing > Preparing for initial contact > Knee – 0 o , tibia externally rotated > Hip – 30 o flexion, femur externally rotates

> Preparing for initial contact

> Knee – 0 o , tibia externally rotated

> Hip – 30 o flexion, femur externally rotates

State to State Conditions

bibliography UNDERSTANDING NORMAL & PATHOLOGICAL GAIT Mahmoud Sarmini, M.D. Assistant Prof. LSU-PM&R Gait Evaluation Joshua Landau, MD Gar Wynne, MD http://www.upstate.edu/cdb/grossanat/limbs6.shtml http://www.upstate.edu/cdb/grossanat/limbs6.shtml

UNDERSTANDING NORMAL & PATHOLOGICAL GAIT

Mahmoud Sarmini, M.D.

Assistant Prof. LSU-PM&R