Human Gait

HUMAN GAIT

Dr. Hazrat Bilal Malakandi, PTDPT (IPM&R, KMU), MSPT (KMU), CHPE (KMU)

Senior Lecturer (NCS University System, Peshawar)

INTRODUCTION TO HUMAN GAIT

Human gait may be define as “ the translatory progression of the human body as a whole, produced by coordinated, rotatory movements of the body segments” is known as gait or human locomotion

TASKSWinter proposed the following five tasks for walking:1. Maintenance of support of HAT2. Maintenance of the upright posture and balance of the

body3. Control of the foot trajectory to achieve safe ground

clearance and gentle heel or toe landing.4. Generation of the mechanical energy to maintain the

present forward velocity or to increase forward velocity5. Absorption of the mechanical energy for shock

absorption and stability or to decrease the forward velocity of the body

GAIT INTIATION Gait initiation may be defined as an activity that

includes the series or sequence of events that occur from the initiation of movement to the beginning of gait cycle.

Gait initiation begins in erect standing posture with activation of the tabilais anterior and vastus lateralis muscles, in conjunction with an inhibition of the gastrocs muscles, bilateral concentric contraction of the tabilais anterior muscles results in a sagittal torque that inclines the body anteriorly from ankles.

The CoP is described as shifting either posteriorly and laterally or posteriorly and medially.

Abduction of the swing hip occurs almost simultaneously with contractions of the tabilais anterior and vastus lateralis muscles and produces a coronal torque which propel the body toward the support limb.

Total duration of the initiation phase is about 0.64 seconds.

KINEMATICSPhases of the Gait cycle

Gait cycle which is also called as stride is the time interval or sequence of motions which occurs between two consecutive initial contacts of the same foot i.e. from heel strike of the right extremity to heel strike again of the right extremity

Distance covered one gait cycle is called the stride length

PHASES OF GAIT CYCLE

During gait cycle each extremity passes through two major phases1. Stance phase----60%2. Swing phase-----40%

There are two periods of “double support” in which one extremity is in initial contact and the other one leaves the ground

At normal walking speed each period of double support occupies 11% of the gait cycle which a total duration of 22% of the gait cycle, normally 20% is used.

The body is supported on a single limb for a duration which makes 80% of the gait cycle.

DIVISONS OF PHASES

Two most common terminologies for the divisions of phases into events of the gait cycle are1. Traditional (T)2. Rancho Los Amigos (RLA)

In both conventions the gait cycle is divided into percentiles that will be used to clarify events and phases

EVENTS IN STANCE PHASES

1. Heel contact or heel strike (T) refers to the instant at which the heel of the leading extremity strikes the ground. Initial contact (T and RLA) refers to the instant the foot of the leading extremity strikes the ground. In normal gait, the heel is the point of contact. In abnormal gait, it is possible for the whole foot or the toes, rather than the heel, to make initial contact with the ground. The term initial contact will be used in referring to this event.

2. Foot flat (T) in normal gait occurs after initial contact at approximately 7% of the gait cycle . It is the first instant during stance when the foot is flat on the ground.

3. Midstance (T) is the point at which the body weight is directly over the supporting lower extremity. usually about 30% of the gait cycle. Heel-off (T) is the point at which the heel of the reference extremity leaves the ground , usually about 40% of the gait cycle.

4. Toe-off (T and RLA) is the instant at which the toe of the foot leaves the ground , usually about 60% of the gait cycle.

EVENTS IN SWING PHASES

1. Acceleration, or early swing phase (T), begins once the toe leaves the ground and continues until midswing, or the point at which the swinging extremity is directly under the body .

2. Initial swing (RLA) begins when the toe leaves the ground and continues until maximum knee flexion occurs.

1. Midswing (T) occurs approximately when the extremity passes directly beneath the body, or from the end of acceleration to the beginning of deceleration. Midswing (RLA) encompasses the period from maximum knee flexion until the tibia is in a vertical position.

2. Deceleration (T), or late swing phase, occurs after midswing when limb is decelerating in preparation for heel strike. Terminal swing (RLA) includes the period from the point at which the tibia is in the vertical position to a point just before initial contact.

SWING PHASE

GAIT TERMINOLOGIES

Time and distances are two basic parameters of motion.

1. Temporal variables2. Distance variables

TEMPORAL VARIABLES

1. Stance time2. Single limb support time3. Double support time4. Swing time5. Stride time6. Step time7. Cadence8. speed

DISTANCE VARIABLES

1. Stride length2. Step length3. Step width4. Degree of toe out

stance time Amount of time spent during stance phase

of Gait cycle of one extremity.

Single support time

Amount of time that spent during the period when only one extremity is on the supporting surface in a gait cycle

Double support time

Amount of the time spent with both feet on the ground during one gait cycle The time of double support may be

increased in elder patients and in those having balance disorders

The time of double support decreases when speed of walking increases

Stride duration

Amount of time spent in completion of one stride or Gait cycle

One stride duration for a normal stride is 1 second.

Changes occur in stride length during normal, slow, fast walking.

Stride length

Gait cycle is also called stride The linear distance between heel strike of one

extremity and when the same extremity heel strike again ( time spent in a gait cycle of one extremity)

A stride include two steps, right and left Stride length greatly varies among individual

because it is effected by leg length, gender, age. Stride length decreases with increase in age

Step lengthLinear distance between two successive points of the opposite extremities. Comparison of the right and left steps provides an

indication of gait symmetry, the more equal are the step length more symmetrical will be the gait

Step duration

The amount of time spent in completion of a single step. Its measurements is expressed as sec/step When there is weakness or pain in an

extremity step duration may be decreased on the effected side while increased on the unaffected side

cadenceThe number of steps taken by a person per unit timeCadence=number of steps/sec or min

Shorter step length will result in increase cadence at a given velocity

When a person is walking with cadence between 80 and 120 steps/min, then cadence and stride length have a linear relationship

If cadence increases the double support time decreases and vice versa

Normal cadence , man=110 steps/min Normal cadence, woman=116 steps/min

Walking velocity

Is the rate of linear forward motion of the body in a specific direction

It can be measured as, cm/sec, meter/min or miles/hour

If the direction is not specified than term walking velocity is called “walking speed”

Walking velocity or speed=distance walked/ timeDistance(cm, m, miles, km)Time(sec, min, hour)

Speed of gait may be referred as slow, free or fast

Free gait speed refer to person normal walking speed

Slow or fast speed of gait refer to slower or faster speed than person normal walking speed.

Step width

Step width, or width of the walking base

It is measured by the linear distance between the mid point of the heel of one foot and the same point of the other foot.

Step width increases if there is increased demand for side to side stability.

Normal is 5-10cm

Degree of toe outIt is the angle of foot placement(FP) and may be found by measuring the angle formed by each foot line of progression and a line which intersect the center of heel and second toe.

Normal angle = 7 degree Angle of toe-out decreases as the speed of

walking increases

Path of Center of Gravity

Center of Gravity (CG):– midway between the hips– Few cm in front of S2

Least energy consumption if CG travels in straight line

Path of Center of Gravity

A. Vertical displacement: Rhythmic up & down

movement Highest point: midstance Lowest point: double support Average displacement: 5cm Path: extremely smooth

sinusoidal curve

Path of Center of Gravity

B. Lateral displacement: Rhythmic side-to-side

movement Lateral limit: midstance Average displacement: 5cm Path: extremely smooth

sinusoidal curve

Determinants of Gait Saunder determinants

Six optimizations used to minimize excursion of CG in vertical & horizontal planes

Reduce significantly energy consumption of ambulation

Classic papers: Sanders, Inman (1953)

Determinants of Gait Saunder determinants

1) Pelvic rotation2) Pelvic tilt3) Knee flexion in stance phase4) Ankle mechanism5) Foot mechanism6) Lateral displacement of body

Determinants of Gait :

(1) Pelvic rotation: Forward rotation of the pelvis in the horizontal

plane approx. 8o on the swing-phase side Enables a slightly longer step-length w/o further

lowering of CG

Determinants of Gait :

(2) Pelvic tilt: 5o dip of the swinging side (i.e. hip adduction) In standing, this dip is a positive Trendelenberg sign

Determinants of Gait :

(3) Knee flexion in stance phase: Approx. 20o dip Shortens the leg in the middle of stance phase

Determinants of Gait :

(4) Ankle mechanism: Lengthens the leg at heel contact Smoothens the curve of CoG

Determinants of Gait :

(5) Foot mechanism: Lengthens the leg at toe-off as ankle moves from

dorsiflexion to plantarflexion Smoothens the curve of CG

Determinants of Gait :

(6) Lateral displacement of body: The normally narrow width of the walking base

minimizes the lateral displacement of CG

JOINT MOTIONS The approx. ROM needed in normal gait and the time

of occurrence of the maximum flexion/extension for each major joint may be determined by examining the joint angels

These angles varies with age, gender, and walking speed.

Approx. values may be calculated

Anatomical position for Hip, Knee, Ankle are considered as 0 degree, while the flexion for the hip, knee, and dorsiflexion of the ankle is considered as positive values and extension and planter flexion are given negative values

SAGGITAL PLANEHIP JOINT

During stance phase hip achieve maximum flexion(approx. +20 degree) at initial contact at 0% of the gait cycle and its most extended position (approx. -20 degrees) at about 50% of the gait cycle, between heel-off and toe-off

During swing phase (mid-swing) hip joint reaches its maximum flexion (approx. +30 degrees).

KNEE JOINT The knee is straight (0 degree) at initial

contact and nearly straight just before heel-off at 40% of the gait cycle.

During foot-flat of the gait cycle the knee reaches it maximum flexion of (approx. +15 degree)

During swing phase(acceleration) the knee reaches upto 60 degree flexion at 70% of gait cycle

ANKEL JOINT

The ankle reaches maximum dorsi flexion of ( approx. +7 degree) at heel-off at 40% of the gait cycle and reaches maximum planter flexion( approx. -25 degrees) at toe-off 60% of the gait cycle

JOINT MOTIONS STANCE PHASESagittal Plane

JOINT MOTIONS SWING PHASESagittal Plane

GRAPHICAL PRESENTATION

NORMAL WALKING

For normal walking: Hip: ROM approx. 20-30 degree of flexion

and extension Knee: ROM, 0 degree to 60 degree of

flexion Ankle: ROM, 25 degree planter flexion to 7

degree dorsi flexion*** If ROM of the above joint are not sufficient than considerable deviation will occur from the normal gait

FRONTAL PLANE JOINT ANGLES

During the first 20% of the stance of the gait cycle, pelvis or the contralateral side drops about 5 degree which results in hip adduction of the supporting limb.

The hip abducts smoothly to 5 degree of abduction, peaking about toe-off, then returns to neutral at initial contact

Knee remains more or less in neutral position except for a brief abduction peaking at about 7 degrees in mid swing and then returns to neutral position

Ankle everts from 5 degrees of inversion to 5 degree of eversion in early stance and inverts during push-off

TRANSVERSE ANGLES

Hip externally rotates until approx. midswing and then internal rotates to near neutral before initial contact.

The knee joint remains relatively neutral through out most of the gait cycle but external rotates in late stance until about foot flat.

The ankle has three rapid reversals of rotation from about 40% of the gait cycle until initial contact and reaches a point of maximum external rotation at about foot flat.

TRANSVERSE PLANE

STAIR GAIT

Stair climbing is an important mode of locomotion having many similarities to that of level ground locomotion, the difference between the two modes are extremely important for the patient population.

The muscle strength and ROM required for locomotion on level ground does,t ensure that the patient will be able to climb stairs.

The trunk ROM during level ground is similar to trunk ROM during descent but differed from the stair gait during ascending in all planes, trunk flexion during ascending gait is at least double to that of trunk flexion in descending and level ground gait.

Gait on stair is similar to level ground walking in that stair gait involves both swing and stance phases, and to carry HAT.

STAIR GAIT The net internal movements of the hip, knee, ankle

during stair ascending and descending when compared to level ground walking, the internal knee extensor movement in both ascending and descending was approx. three times larger that that of level ground.

Ankle moments are approx. the same. Power generation mainly occur during ascending and

power generation absorption occur during descending

RUNNING GAIT Locomotion mode which is similar to walking, but

there are certain differences. A person able to walk on level ground may not able

to run, running requires greater balance, muscle strength, and ROM as walking.

Body needs greater balance as running is characterized by reduced base due to lake of double support and the presence of floating periods in which both extremities are out of contact with the ground. Presence of floating periods increases will increase the speed of the running.

RUNNING GAIT Knee is flexed about 20 degree when foot strike the ground

which also increases forces on the PF joint. Typical base of the support is considerably less than

normal walk i.e.: 2-4inches Both the feet falls in the same line of progression so the

center of mass of the body must be placed over single supported foot.

To compensate for the reduced base of support the functional varus angle increases. Which is the angle between bisection of the lower leg and floor, it increases 5 degree during running

RUNNING GAIT

ABNORMAL GAIT

Many causes of abnormal gait, it may be temporary, due to sprained ankle or permanent following stroke. Following are the abnormal gaits based on general causes

Muscular weakness/paralysis Joint muscle range-of-motion (ROM) limitation Neurological involvement Pain Leg length discrepancy

Muscular weakness

Gluteus Maximus gait Gluteus Medius gait Quadriceps gait Hamstring gait

Types of pathological gait Due to pain –

– Antalgic or limping gait – (Psoatic Gait) Due to neurological disturbance –

– Muscular paralysis – both »Spastic (Circumductory Gait, Scissoring

Gait, Dragging or Paralytic Gait, Robotic Gait[Quadriplegic]) and

»Flaccid (Lurching Gait, Waddaling Gait, Gluteus Maximus Gait, Quadriceps Gait, Foot Drop or Stapping Gait)

Types of pathological gait

–Cerebellar dysfunction (Ataxic Gait)–Loss of kinesthetic sensation

(Stamping Gait)–Basal ganglia dysfunction (Festinaut

Gait)

Due to abnormal deformities –– Equinus gait– Equinovarous gait– Calcaneal gait– Knock & bow knee gait– Genurecurvatum gait

Due to Leg Length Discrepancy (LLD) ––Equinnus gait

Antalgic gait This is a compensatory gait pattern adopted in order

to remove or diminish the discomfort caused by pain in the LL or pelvis.

Characteristic features:– Decreased in duration of stance phase of the

affected limb (unable of weight bear due to pain)– There is a lack of weight shift laterally over the

stance limb and also to keep weight off the involved limb

– Decrease in stance phase in affected side will result in a decrease in swing phase of sound limb.

Psoatic gait

Psoas bursa may be inflamed & edematous, which cause limitation of movement due to pain & produce a atypical gait. –Hip externally rotated–Hip adducted–Knee in slight flexion

This process seems to relieve tension of the muscle & hence relieve the inflamed structures.

Gluteus maximus gait

The gluteus maximus act as a restraint for forward progression.

The trunk quickly shifts posteriorly at heel strike (initial contact).

This will shift the body’s COG posteriorly over the gluteus maximus, moving the line of force posterior to the hip joints.

Cont ……

With foot in contact with floor, this requires less muscle strength to maintain the hip in extension during stance phase.

This shifting is referred to as a “Rocking Horse Gait” because of the extreme backward-forward movement of the trunk.

Gluteus medius gait It is also known as “Trendelenberg gait” or

“Lurching Gait” when one side affected. The individual shifts the trunk over the

affected side during stance phase.

When right gluteus medius or hip abductor is weak it cause Right side of the pelvis drop when the right leg leaves the ground & begins swing phase.

Cont …..

Shifting the trunk over the affected side is an attempt to reduce the amount of strength required of the gluteus medius to stabilize the pelvis.

Bilateral paralysis, waddling or duck gait. The patient lurch to both sides while walking. The body sways from side to side on a wide

base with excessive shoulder swing.–E.g. Muscular dystrophy

Quadriceps gait

Quadriceps action is needed during heel strike & foot flat when there is a flexion movement acting at the knee.

Quadriceps weakness/ paralysis will lead to buckling of the knee during gait & thus loss of balance.

Patient can compensate this if he has normal hip extensor & plantar flexors.

Compensation:– With quadriceps weakness, the individual may

lean forward over the quadriceps at the early part of stance phase, as weight is being shifted on to the stance leg.

– Normally, the line of force falls behind the knee, requiring quadriceps action to keep the knee from buckling.

– By leaning forward at the hip, the COG is shifted forward & the line of force now falls in front of the knee.

Cont …

– This will force the knee backward into extension.

Another compensatory manoeuvre to use is the hip extensors & ankle plantar flexors in a closed chain action to pull the knee into extension at heel strike (initial contact).

In addition, the person may physically push on the anterior thigh during stance phase, holding the knee in extension.

Genu recurvatum gait or Hamstring Gait

Quadriceps paralysis, Hamstrings are weak or planter flexors contracture, – During stance phase, the knee will go

into excessive hyperextension, referred to as “genu recurvatum” gait.

– If only hamstrings are weak – During the deceleration (terminal

swing) part of swing phase, without the hamstrings to slow down the swing forward of the lower leg, the knee will snap into extension.

Hemiplegic gait With spastic pattern of hemiplegic leg

– Hip into extension, adduction & medial rotation

– Knee in extension, though often unstable

– Ankle in drop foot with ankle plantar flexion and inversion (equinovarus), which is present during both stance and swing phases.

In order to clear the foot from the ground the hip & knee should flex.

But the spastic muscles won’t allow the hip & knee to flex for the floor clearance.

So the patient hikes hip & bring the affected leg by making a half circle i.e. circumducting the leg.

Hence the gait is known as “Circumductory Gait”. Usually, there will be no reciprocal arm swing. Step length tends to be lengthened on the involved

side & shortened on the uninvolved side.

Scissoring gait

It results from spasticity of bilateral adductor muscle of hip.

One leg crosses directly over the other with each step like crossing the blades of a scissor.– E.g. Cerebral Palsy

Dragging or paraplegic gait

There is spasticity of both hip & knee extensors & ankle plantar flexors.

In order to clear the ground the patient has to drag his both lower limb swings them & place it forward.

Cerebral Ataxic or Drunkard’s gait

Abnormal function of cerebellum result in a disturbance of normal mechanism controlling balance & therefore patient walks with wider BOS.

The wider BOS creates a larger side to side deviation of COG.

This result in irregularly swinging sideways to a tendency to fall with each steps.

Hence it is known as “Reeling Gait”.

Sensory ataxic gait

This is a typical gait pattern seen in patients affected by tabes dorsalis.

It is a degenerative disease affecting the posterior horn cells & posterior column of the spinal cord.

Because of lesion, the proprioceptive impulse won’t reach the cerebellum.

The patient will loss his joint sense & position for his limb on space.

Because of loss of joint sense, the patient abnormally raises his leg (high step) jerks it forward to strike the ground with a stamp.

So it is also called as “Stamping Gait”. The patient compensated this loss of joint

position sense by vision. So his head will be down while he is

walking.

Short shuffling or festinate gait or Parkinsonian Gait

Normal function at basal ganglia are:–Control of muscle tone–Planning & programming of normal movements.–Control of associated movements like reciprocal

arm swing.–Typical example for basal ganglia lesion is

parkinsonism.

Parkinsonian Gait

In this gait, the patient will have rigidity and bradykinesia.

He or she will be stooped with the head and neck forward, with flexion at the knees.

The whole upper extremity is also in flexion with the fingers usually extended.

The patient walks with slow little steps. Patient may also have difficulty initiating

steps.

This posture displaces the COG anteriorly. So in order to keep the COG within the

BOS, the patient will take no of small shuffling steps.

Due to loss of voluntary control over the movement, they loses balance & walks faster as if he is chasing the COG.

So it is called as “Festinate Gait”. Since his shuffling steps, it is otherwise

called as “Shuffling Gait”.

Foot drop or slapping gait

This is due to dorsiflexor weakness caused by paralysis of common peroneal nerve.

There won’t be normal heel strike, instead the foot comes in contact with ground as a whole with a slapping sound.

So it is also known as “Slapping gait”.

Cont ….

Due to plantarflexion of the ankle, there will be relatively lengthening at the leading extremity.

So to clear the ground the patient lift the limb too high.

Hence the gait get s its another name i.e. “High Stepping Gait”

Dorsi flexor weakness

Equinus gait

Equinus = Horse Because of paralysis of dorsiflexor which

result in plantar flexor contracture. The patients will walk on his toes (toe

walking). Other cause may be compensation by

plantar flexor for a short leg.

Unequal Leg Length

We all have unequal leg length, usually a discrepancy of approx 1/4 inch between the right and left legs.

Clinically, these smaller discrepancies are often corrected by inserting heel lifts of various thicknesses into the shoe.

Leg length discrepancy (LLD) are divided in ––Minimal leg length discrepancy–Moderate leg length discrepancy –Severe leg length discrepancy

Minimal LLD

Compensation occurs by dropping the pelvis on the affected side.

The person may compensate by leaning over shorter leg (up to 3 inches can be accommodated with these tech).

Moderate LLD

Approx between 3 & 5 cm, dropping the pelvis on the affected side will no longer be effective.

A longer leg is needed, so the person usually walks on the ball of the foot on the involved (shorter) side.

This is called an “Equinnus Gait”.

Severe LLD

It is usually discrepancy of more than 5 inches. The person may compensate in a variety of

ways. Dropping the pelvis and walking in an

equinnus gait plus flexing the knee on the uninvolved side is often used.

To gain an appreciation for how this may feel or look, walk down the street with one leg in the street and the other on the sidewalk.

Equinovarous gait

There will be ankle plantar flexion & subtalar inversion.

So the patient will be walking on the outer border of the foot.– E.g. CETV

Calcaneal gait Result from paralysis plantar flexors causing

dorsiflexor contracture. The patient will be walking on his heel (heel

walking) It is characterized by greater amounts of ankle

dorsiflexion & knee flexion during stance & a shorter step length on the affected side.

Single-limb support duration is shortened because of the difficulty of stabilizing the tibia & the knee.

Knock knee gait

It is also known as genu valgum gait. Due to decreased physiological valgus of

knee. Both the knee face each other widening the

BOS.

Bow leg gait

It is also known as genu varum gait. Knee face outwards. Due to increase increased physiological

valgus of knee. The legs will be in a bowed position.

JOINT/ MUSCLE ROM LIMITATION

Hip flexion contracture Fused hip joint Knee flexion contracture Knee joint fusion Ankle fusion

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