Gait

GAITGAIT

JAYANT SHARMAJAYANT SHARMA

M.S.,D.N.B.,M.N.A.M.S.M.S.,D.N.B.,M.N.A.M.S.

DEFINITIONDEFINITION

Normal GaitNormal Gait = = – Series of rhythmical , alternating Series of rhythmical , alternating

movements of the trunk & limbs which movements of the trunk & limbs which result in the forward progression of the result in the forward progression of the center of gravitycenter of gravity

– series of ‘controlled falls’series of ‘controlled falls’

Gait CycleGait Cycle– Single sequence of functions by Single sequence of functions by one one

limblimb– Begins when reference font contacts Begins when reference font contacts

the groundthe ground– Ends with subsequent floor contact of Ends with subsequent floor contact of

the the same footsame foot

Gait Cycle - Definitions:Gait Cycle - Definitions:Step LengthStep Length = =– Distance between corresponding Distance between corresponding

successive successive points of heel contact of points of heel contact of the opposite feetthe opposite feet

– Rt step length = Lt step lengthRt step length = Lt step length (in (in normal gaitnormal gait

Stride LengthStride Length = =– Distance between successive points of Distance between successive points of

heel contact of the heel contact of the same footsame foot– Double the step length (in normal gait)Double the step length (in normal gait)

Walking BaseWalking Base = =– Side-to-side distance between the line Side-to-side distance between the line

of the two feetof the two feet– Also known as ‘stride width’Also known as ‘stride width’

Normal GaitSTANCE (60-62% gait cycle)

Initial Contact: The moment the foot contacts the ground.

Loading Response: Weight is rapidly transferred onto the outstretched limb, the first period of double-limb support.Midstance: The body progresses over a single, stable limb.Terminal Stance: Progression over the stance limb continues. The body moves ahead of the limb and weight is transferred onto the forefoot.Pre-swing: A rapid unloading of the limb occurs as weight is transferred to the contralateral limb, the second period of double-limb support

SWING (38-40% gait cycle)

Initial Swing: The thigh begins to advance as the foot comes up off the floor.Mid Swing: The thigh continues to advance as the knee begins to extend, the

foot clears the ground.Terminal Swing: The knee extends, the limb prepares to contact the ground.

The contact periodThe contact period

- - Objective:Objective: adapt to terrain, shock adapt to terrain, shock absorption, forward progressionabsorption, forward progression- 0-10% of gait cycle (HC to FFC)- 0-10% of gait cycle (HC to FFC)- at HC: hip flexed, knee extended, ankle - at HC: hip flexed, knee extended, ankle in neutral (90°), STJ supinatedin neutral (90°), STJ supinated- from HC to FFC: knee flexes, ankle - from HC to FFC: knee flexes, ankle plantarflexes, STJ pronatesplantarflexes, STJ pronatesMuscle activityMuscle activity::- long extensors decelerate plantarflexion- long extensors decelerate plantarflexion- tibialis posterior decelerates pronation- tibialis posterior decelerates pronation- gastrocnemius decelerates internal tibial - gastrocnemius decelerates internal tibial rotation rotation

MidstanceMidstance- objective: progression over stationary foot, limb - objective: progression over stationary foot, limb and trunk stabilityand trunk stability- 10 - 30% of gait cycle (FFC to HO)- 10 - 30% of gait cycle (FFC to HO)- knee and hip start to extend- knee and hip start to extend- subtalar joint pronation should have ceased (ie. - subtalar joint pronation should have ceased (ie. neutral)neutral)

Muscle activityMuscle activity::- tibialis posterior and soleus start to supinate STJ- tibialis posterior and soleus start to supinate STJ- peroneus longus stabilizes first ray- peroneus longus stabilizes first ray- triceps surae decelerate forward displacement - triceps surae decelerate forward displacement of tibia, and plantarflex ankle jointof tibia, and plantarflex ankle joint

PropulsionPropulsion- objective: forward progression, foot becomes - objective: forward progression, foot becomes 'rigid lever''rigid lever'- 30 - 60% of gait cycle (HO to TO)- 30 - 60% of gait cycle (HO to TO)- knee flexes, ankle plantarflexes- knee flexes, ankle plantarflexes- subtalar joint rapidly supinates- subtalar joint rapidly supinates- first ray plantarflexes- first ray plantarflexes- 1st MPJ dorsiflexes: toe-off through tip of hallux- 1st MPJ dorsiflexes: toe-off through tip of halluxMuscle activityMuscle activity::- soleus and tibialis posterior assist heel lift- soleus and tibialis posterior assist heel lift- peroneus longus stabilizes first ray- peroneus longus stabilizes first ray- FHL, FHB, AbH, AdH stabilize hallux- FHL, FHB, AbH, AdH stabilize hallux- EHL dorsiflexes hallux- EHL dorsiflexes hallux

Swing phaseSwing phase- objective: forward progression, ground - objective: forward progression, ground clearanceclearance- 60-100% of gait cycle- 60-100% of gait cycle- hip continues to flex- hip continues to flex- knee extends from flexed position- knee extends from flexed position- ankle dorsiflexes- ankle dorsiflexes- STJ slightly pronated at toe-off- STJ slightly pronated at toe-off

Muscle activity:Muscle activity:- long extensors dorsiflex foot for toe clearance- long extensors dorsiflex foot for toe clearance- tibialis anterior dorsiflexes the first ray- tibialis anterior dorsiflexes the first ray

The Functional Phases of the Gait Cycle

Stance (62%)IC LR

Weight Acceptance

MS TS

Single Limb Support

Swing (38%)PSw ISw MSw TSw

Swing Limb Advance

Normal Stride Characteristics

A. Cadence: steps / timeAdult: approx. 2 steps/secFemales (20 - 69 years old): 121 ∀ 8.5 steps/minMales (20 - 69 years old): 111 ∀ 7.6 steps/minCadenceCadence ==– Number of steps per unit timeNumber of steps per unit time– Normal: 100 – 115 Normal: 100 – 115 steps/minsteps/min– Cultural/social variationsCultural/social variations

Comfortable Walking SpeedComfortable Walking Speed (CWS)(CWS) = =– Least energy consumption per unit Least energy consumption per unit

distancedistance– Average= Average= 80 m/min80 m/min (~ 5 km/h , ~ (~ 5 km/h , ~

3 mph)3 mph)

– VelocityVelocity ==

Distance covered by the body in unit Distance covered by the body in unit timetime

Usually measured in Usually measured in m/sm/s

Instantaneous velocity varies during Instantaneous velocity varies during the gait cyclethe gait cycle

Average velocity (m/min) = step length Average velocity (m/min) = step length (m) x cadence (steps/min)(m) x cadence (steps/min)

PhasesPhases::Stance PhaseStance Phase: : Swing PhaseSwing Phase: :

reference limb reference limb reference limb reference limb in contact in contact notnot in in

contact contact with the floor with the floor with the with the

floorfloor

SupportSupport::(1) (1) Single SupportSingle Support: only one foot in contact : only one foot in contact

with the floorwith the floor

(2) (2) Double SupportDouble Support: both feet in contact with : both feet in contact with floorfloor

Stance phase:Stance phase:1. 1. Heel contactHeel contact: : ‘Initial contact’‘Initial contact’

2. 2. Foot-flatFoot-flat: : ‘Loading response’, initial contact of ‘Loading response’, initial contact of forefoot w. groundforefoot w. ground

3. 3. MidstanceMidstance: : greater trochanter in alignment w. greater trochanter in alignment w. vertical bisector of footvertical bisector of foot

4. 4. Heel-offHeel-off: : ‘Terminal stance’‘Terminal stance’

5. 5. Toe-offToe-off: : ‘Pre-swing’‘Pre-swing’

Swing phase:Swing phase:1. 1. AccelerationAcceleration: ‘Initial swing’: ‘Initial swing’2. 2. MidswingMidswing: swinging limb overtakes the limb in : swinging limb overtakes the limb in stance stance 3. 3. DecelerationDeceleration: ‘Terminal swing’: ‘Terminal swing’

Time FrameTime Frame::A. Stance vs. Swing:A. Stance vs. Swing:

Stance phaseStance phase = = 60% of gait cycle60% of gait cycleSwing phaseSwing phase = = 40%40%

B. Single vs. Double support:B. Single vs. Double support:Single support= Single support= 40% of gait cycle40% of gait cycleDouble support=Double support= 20%20%

With increasing walking speedsWith increasing walking speeds::Stance phase:Stance phase: decreasesdecreasesSwing phase:Swing phase: increasesincreasesDouble support:Double support: decreasesdecreases

RunningRunning::By definition: walking without double supportBy definition: walking without double supportRatio stance/swing reversesRatio stance/swing reversesDouble support disappears. ‘Double swing’ Double support disappears. ‘Double swing’ developsdevelops

Path of Center of GravityPath of Center of Gravity

Center of Gravity (CG):Center of Gravity (CG):– midway between the hipsmidway between the hips– Few cm in front of S2Few cm in front of S2

Least energy consumption if CG Least energy consumption if CG travels in straight linetravels in straight line

Path of Center of GravityPath of Center of GravityVertical displacementVertical displacement::

Rhythmic up & down Rhythmic up & down movementmovementHighest point: midstanceHighest point: midstanceLowest point: double Lowest point: double supportsupportAverage displacement: Average displacement: 5cm5cmPath: extremely smooth Path: extremely smooth sinusoidal curvesinusoidal curve

Lateral displacementLateral displacement::

Rhythmic side-to-sideRhythmic side-to-side movementmovement

Lateral limit: midstanceLateral limit: midstance

Average displacement: Average displacement: 5cm5cm

Path: extremely smooth Path: extremely smooth sinusoidal curvesinusoidal curve

Overall Overall displacementdisplacement::Sum of vertical & Sum of vertical & horizontal horizontal displacementdisplacementFigure ‘8’ Figure ‘8’ movement of CG movement of CG as seen from AP as seen from AP viewview

Determinants of Gait :Determinants of Gait :

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

Reduce significantly energy Reduce significantly energy consumption of ambulationconsumption of ambulation

Classic papers: Sanders, Inman Classic papers: Sanders, Inman (1953)(1953)

Pelvic rotationPelvic rotation:: Forward rotation of the pelvis in the horizontal Forward rotation of the pelvis in the horizontal

plane approx. 8plane approx. 8oo on the swing-phase side on the swing-phase side Reduces the angle of hip flexion & extensionReduces the angle of hip flexion & extension Enables a slightly longer step-length w/o Enables a slightly longer step-length w/o

further lowering of CGfurther lowering of CG

Pelvic tiltPelvic tilt::5o dip of the swinging side (i.e. hip adduction)5o dip of the swinging side (i.e. hip adduction)In standing, this dip is a positive Trendelenberg In standing, this dip is a positive Trendelenberg signsignReduces the height of the apex of the curve of Reduces the height of the apex of the curve of CGCG

Knee flexion in stance phaseKnee flexion in stance phase::Approx. 20o dipApprox. 20o dipShortens the leg in the middle of stance Shortens the leg in the middle of stance phasephaseReduces the height of the apex of the Reduces the height of the apex of the curve of CGcurve of CG

Ankle mechanismAnkle mechanism::Lengthens the leg at heel contactLengthens the leg at heel contactSmoothens the curve of CGSmoothens the curve of CGReduces the lowering of CGReduces the lowering of CG

Foot mechanismFoot mechanism::Lengthens the leg at toe-off as Lengthens the leg at toe-off as ankle moves from dorsiflexion to ankle moves from dorsiflexion to plantarflexionplantarflexionSmoothens the curve of CGSmoothens the curve of CGReduces the lowering of CGReduces the lowering of CG

Lateral displacement of bodyLateral displacement of body::The normally narrow width of the walking The normally narrow width of the walking base minimizes the lateral displacement base minimizes the lateral displacement of CGof CGReduced muscular energy consumption Reduced muscular energy consumption due to reduced lateral acceleration & due to reduced lateral acceleration & decelerationdeceleration

Gait Analysis – ForcesGait Analysis – Forces

Forces which have the most Forces which have the most significant Influence are due to:significant Influence are due to:

(1) gravity(1) gravity

(2) muscular contraction(2) muscular contraction

(3) inertia(3) inertia

(4) floor reaction(4) floor reaction

The force that the foot The force that the foot exerts on the floor due exerts on the floor due to gravity & inertia is to gravity & inertia is opposed by the ground opposed by the ground reaction forcereaction forceGround reaction force Ground reaction force (RF) may be resolved (RF) may be resolved into horizontal (HF) & into horizontal (HF) & vertical (VF) vertical (VF) components.components.Understanding joint Understanding joint position & RF leads to position & RF leads to understanding of understanding of muscle activity during muscle activity during gaitgait

At initial heel-contact: ‘heel At initial heel-contact: ‘heel transient’transient’At heel-contact:At heel-contact:

Ankle: Ankle: DF DF Knee:Knee: QuadQuadHip:Hip: Glut. Max&HamstringsGlut. Max&Hamstrings

Low muscular demand:Low muscular demand: – ~ 20-25% max. muscle strength~ 20-25% max. muscle strength– MMT of ~ 3MMT of ~ 3++

COMMON GAIT ABNORMALITIESCOMMON GAIT ABNORMALITIES

A.A. Antalgic GaitAntalgic Gait

B.B. Lateral Trunk bendingLateral Trunk bending

C.C. Functional Leg-Length Functional Leg-Length DiscrepancyDiscrepancy

D.D. Increased Walking BaseIncreased Walking Base

E.E. Inadequate Dorsiflexion ControlInadequate Dorsiflexion Control

F.F. Excessive Knee ExtensionExcessive Knee Extension

Hip abductor load & hip joint reaction forceHip abductor load & hip joint reaction force

Hip abductor load & hip joint reaction forceHip abductor load & hip joint reaction force

Swing leg: longer than stance legSwing leg: longer than stance leg

4 common compensations:4 common compensations:A. CircumductionA. Circumduction

B. Hip hikingB. Hip hiking

C. SteppageC. Steppage

D. VaultingD. Vaulting

Functional Leg-Length DiscrepancyFunctional Leg-Length Discrepancy

Increased Walking BaseIncreased Walking Base

Normal walking base: 5-10 cmNormal walking base: 5-10 cm

Common causes:Common causes:– DeformitiesDeformities

Abducted hipAbducted hip

Valgus kneeValgus knee

– InstabilityInstabilityCerebellar ataxiaCerebellar ataxia

Proprioception deficitsProprioception deficits

Inadequate Dorsiflexion ControlInadequate Dorsiflexion Control

In stance phase (Heel contact – Foot In stance phase (Heel contact – Foot flat):flat):

Foot slapFoot slap

In swing phase (mid-swing):In swing phase (mid-swing):

Toe dragToe drag

Causes:Causes:– Weak Tibialis Ant.Weak Tibialis Ant.– Spastic plantarflexorsSpastic plantarflexors

Excessive knee extensionExcessive knee extension

Loss of normal knee flexion during Loss of normal knee flexion during stance phasestance phaseKnee may go into hyperextensionKnee may go into hyperextensionGenu recurvatumGenu recurvatum: hyperextension : hyperextension deformity of kneedeformity of kneeCommon causes:Common causes:– Quadriceps weakness (mid-stance)Quadriceps weakness (mid-stance)– Quadriceps spasticity (mid-stance)Quadriceps spasticity (mid-stance)– Knee flexor weakness (end-stance)Knee flexor weakness (end-stance)

Lateral Trunk bendingLateral Trunk bending

TrendelenbergTrendelenberg gait gait

Usually unilateralUsually unilateral

Bilateral = waddling gaitBilateral = waddling gait

Common causes:Common causes:A. Painful hipA. Painful hip

B. Hip abductor weaknessB. Hip abductor weakness

C. Leg-length discrepancyC. Leg-length discrepancy

D. Abnormal hip jointD. Abnormal hip joint

Antalgic GaitAntalgic Gait

Gait pattern in which stance phase Gait pattern in which stance phase on affected side is shortenedon affected side is shortened

Corresponding increase in stance on Corresponding increase in stance on unaffected sideunaffected side

Common causes: OA, Fx, tendinitis Common causes: OA, Fx, tendinitis

Velocity: distance/timeAdult: 1.4 m/secFemales (20 - 69 years old): 79.3 ∀ 9.5 m/minMales (20 - 69 years old): 82.1 ∀ 10.3 m/min

C. Stride length: right heel strike to right heel strikeAdult: 1.5 mFemales (20 - 69 years old): 1.32 ∀ .13 mMales (20 - 69 years old): 1.48 ∀ .15 m

Abnormalities during Weight Acceptance:Joint Deviation: Possible CauseTrunk

Backward lean: To decrease demand on hip extensors (glut max)

Forward lean: Due to increased hip flexion (joint contracture or mm weakness)

Lateral Lean: R/L Weak hip abductorsPelvis

Contralateral drops: Weak hip abductors on reference limb

Ipsilateral drops: Compensation for shortened limb

Hip Excessive flexion: Hip flexion contracture, excessive knee flexion Limited flexion: Weakness of hip flexors, decreased hip

flexionKnee

Excessive flexion: Knee pain, weak quads, short leg on opposite side

Hyperextension: Decreased dorsiflexion, weak quads Extension thrust: Intention to increase limb stability

Ankle Forefoot contact: Heel pain, excessive knee flexion, pf

contracture Foot flat contact: Dorsiflexion contracture, weak

dorsiflexors Foot slap: Weak dorsiflexors Toes Up: Compensation for weak anterior tib

Abnormalities during Single Limb Support:

Joint Deviation: Possible Cause

Trunk Backward lean: To decrease demand on hip extensors (glut max)Forward lean: Due to increased hip flexion (joint contracture or mm weakness)Lateral Lean: R/L Weak hip abductors

Pelvis Contralateral drops: Weak hip abductors on reference limbIpsilateral drops: Compensation for shortened limbAnterior Pelvic Tilt: Hip flexion contractureHip Limited flexion: Weakness of hip flexors, decreased hip flexionInternal Rotation: Weak external rotators, femoral anteversionExternal Rotation: Retroversion, limited dorsiflexionAbduction: Reference limb longerAdduction: Secondary to contralateral pelvic drop

Knee Excessive flexion: Knee pain, weak quads, short leg on opposite sideHyperextension: Decreased dorsiflexion, weak quadsExtension thrust: Intention to increase limb stabilityWobbles: Impaired proprioceptionVarus: Joint instability, bony deformityValgus: Lateral trunk lean, Joint instability, bony deformity

Ankle Excessive plantarflexion: Weak quads, Impaired proprioception, ankle painEarly heel off: Tight dorsiflexors,Increased pronation: STJ deformity,Toes Up: Compensation for weak anterior tib

Abnormalities during Swing Limb Advance:Joint Deviation: Possible Cause

Trunk Backward lean: To decrease demand on hip extensors (glut max)Forward lean: Due to increased hip flexion (joint contracture or mm weakness)Lateral Lean: R/L Weak hip abductorsPelvis Hikes: Clear swing limbIpsilateral drops: Weak hip abductors on contralateral sideHip Limited flexion: Weakness of hip flexors, decreased hip flexion, hip pain

Knee Limited flexion: Excess hip flexion, knee painExcess flexion: Knee contracture, weak quadsAnkle Excessive plantarflexion: Weak quads, Impaired proprioception, ankle painDrag: Secondary to limited hip flexion, knee flexion or excess pfContralateral Vaulting: Compensation for limited flexion of swing or long swinglimbToes Inadequate extension:Limited joint motion, forefoot pain, no heel offClawed/hammered: Imbalance of long toe extensors and intrinsics, weak pf

Running GaitVariations from walking

STANCE (30 - 40%)Foot Strike:Mid-support:Take-off (propulsion)SWING (60 - 70%)Follow through:Forward swing:Foot descent:

list of common overuse injuries associated list of common overuse injuries associated with poor gait biomechanics:with poor gait biomechanics:Shin splintsShin splints Plantar Plantar fasciitsfasciits IliotibialIliotibial band syndrome band syndrome (runners knee) (runners knee) Patella tendonitisPatella tendonitis (jumpers knee) (jumpers knee) PatelloPatello-femoral knee pain-femoral knee pain Achilles tendonitisAchilles tendonitis Lower back pain Lower back pain

Shock absorption and energy conservation are Shock absorption and energy conservation are important aspects of efficient gait. Altered joint important aspects of efficient gait. Altered joint motion or absent muscle forces may increase motion or absent muscle forces may increase joint reaction (contact) forces and lead joint reaction (contact) forces and lead subsequently to additional pathology. In early subsequently to additional pathology. In early stance, nearly 60% of one's body weight is loaded stance, nearly 60% of one's body weight is loaded abruptly (less than 20 milliseconds) onto the abruptly (less than 20 milliseconds) onto the ipsilateral limb. This abrupt impact is attenuated ipsilateral limb. This abrupt impact is attenuated at each of the lower extremity joints. Loading at each of the lower extremity joints. Loading response plantar flexion is passive, substantially response plantar flexion is passive, substantially restrained by eccentric work of pretibial muscles. restrained by eccentric work of pretibial muscles. The absorptive work by pretibial muscles delays The absorptive work by pretibial muscles delays forefoot contact until late in the initial double forefoot contact until late in the initial double support period (7-8% GC).support period (7-8% GC).

At initial contact, external (ground At initial contact, external (ground reaction) forces applied to the contact foot reaction) forces applied to the contact foot produce a tendency toward knee flexion. produce a tendency toward knee flexion. Repositioning the knee (recurvatum) Repositioning the knee (recurvatum) increases knee mechanical stability, but at increases knee mechanical stability, but at the cost of increased contact forces and the cost of increased contact forces and shock generation. A balance between knee shock generation. A balance between knee stability and shock absorption is achieved stability and shock absorption is achieved by eccentric quadriceps contractions by eccentric quadriceps contractions during loading response. The impact of during loading response. The impact of loading is minimized at the hip during loading is minimized at the hip during single support through hip abductor single support through hip abductor muscle contraction. muscle contraction.

Energy conservationEnergy conservationAmbulation always is associated with Ambulation always is associated with metabolic costs. These costs are metabolic costs. These costs are relatively minor in normal adults relatively minor in normal adults performing free speed level walking. performing free speed level walking. The self-selected walking speed in The self-selected walking speed in normal adults closely matches the normal adults closely matches the velocity that minimizes metabolic velocity that minimizes metabolic work.work.