biomechatronics - lecture 9. clinical gait analysis

VU University Medical CenterAmsterdam The Netherlands

Clinical Gait Analysis

dr. ir. Jaap Harlaar

j.harlaar@vumc.nlwww.vumc.nl/revalidatie

Human Movement Laboratory

Department of Rehabilitation Medicine

VU UniversityMedical Center

Amsterdam

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casus

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Goal setting vs. tools

• problems with specific activities• >> goal setting at this level• specific interventions might work• movement analysis: biomechanics

External Factors

Personal factors

Function / Anatomy

(Impairments)

Activities(Disabilities)

Participation(Handicaps)

Disease

International Classification of Functions(ICF)

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DecisionDisability assessment

General aim of treatment (disability level)no treatment

DecisionMovement analysis

Specific treatment

nestedComplete decision scheme

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casus

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GAIT

Gait and movement analysis in clinical practice of rehabilitation medicine

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Goal of walking

• To go from one place to another

• Walking speed, Energy & Safety

HOW ? By repeatedly placing one foot in front of the other

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Footsteps

Stridelength = StepRight + StepLeft

Left steplengthRight steplength

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Footsteps (asymmetric)

Stridelength = Right step + Left step

Left steplengthRight steplength

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www.gaitrite.com

Measure footsteps

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www.gaitrite.com

Measure footsteps

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Goal of walking

Walking speed [m/s]

3.6 km/h = 1 m/s

Cadence [ steps/min]

Stridelength [m]

x / 120 =

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Walking speed=stride length*cadence

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 20 40 60 80 100 120 140 160

Step rate (steps/min)

Strid

e le

ngth

(m)

0.25 m/s0.50 m/s0.75 m/s1.00 m/s1.25 m/s1.50 m/s1.75 m/s2.00 m/s

1.50 x 60 / 120 = .75

1.00 x 90 / 120 = .75

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Body length and stride length

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What is the optimal stridelength ?

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 20 40 60 80 100 120 140 160

Step rate (steps/min)

Stri

de le

ngth

/ Bo

dy L

engt

h 0.25 m/s0.50 m/s0.75 m/s1.00 m/s1.25 m/s1.50 m/s1.75 m/s2.00 m/s

StrideLengthBodyHeight =0.008 * StepRate

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Energy

Walking speed

Cadence

Stridelength

x Energy Cost

Statute

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Energy measurements during gait

• (ambulatory) oxygenrecording

• one ml O2 / min• = 5 cal / min • = 20 J/min

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Human gait is very efficient...

optimal:~3.4 J/kg.m

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How far can you walk on a pastry ?

250 kcalEnergy cost at optimal speed= 0.8 cal/kg.meter

250.000/(0.8*70)=4,5 km

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Metabolic Energy Measurement

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casus

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One stride lasts from initial foot contact until the next ipsilateral initial foot contact

the gaitcycle

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normalized time: 0 % - 100 %

the gaitcycle (2)

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Heelstrike & Toe-off

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the gaitcycle (3)

0 % -- stance -- 60 % -swing-100%

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the gaitcycle (4)

-- 50 % --

LEFT SWING LEFT STANCE

RIGHT SWINGRIGHT STANCE

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the gaitcycle (5)

LEFT SWING LEFT STANCE

RIGHT SWINGRIGHT STANCE

RIGHT SINGLE SUPPORT

LEFT SINGLE SUPPORT

DOUBLE SUPPO

RT

DOUBLE SUPPO

RT

DOUBLE SUPPO

RT

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Functional division of gait phases(after J. Perry)

Stride (gait cycle)

Stance Swingperiods

WeightAcceptance

Single LimbSupporttasks

LimbAdvancement

InitialContact

LoadingRespons

e

MidStance

Terminal Stance

PreSwing

InitialSwing

MidSwing

Terminal Swing

phases

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Initial Contact 0 %

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Loading Response 0-10 %

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Functional division of gait phases(after J. Perry)

Stride (gait cycle)

Stance Swingperiods

WeightAcceptance

Single LimbSupporttasks

LimbAdvancement

InitialContact

LoadingRespons

e

MidStance

Terminal Stance

PreSwing

InitialSwing

MidSwing

Terminal Swing

phases

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Midstance 10 - 30 %

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Terminal Stance 30 - 50 %

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Functional division of gait phases(after J. Perry)

Stride (gait cycle)

Stance Swingperiods

WeightAcceptance

Single LimbSupporttasks

LimbAdvancement

InitialContact

LoadingRespons

e

MidStance

Terminal Stance

PreSwing

InitialSwing

MidSwing

Terminal Swing

phases

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Pre-Swing 50 - 60 %

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Initial-Swing 60 - 73 %

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Functional division of gait phases(after J. Perry)

Stride (gait cycle)

Stance Swingperiods

WeightAcceptance

Single LimbSupporttasks

LimbAdvancement

InitialContact

LoadingRespons

e

MidStance

Terminal Stance

PreSwing

InitialSwing

MidSwing

Terminal Swing

phases

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Mid-Swing 73 - 87 %

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Terminal-Swing 87 - 100 %

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Functional division of gait phases(after J. Perry)

Stride (gait cycle)

Stance Swingperiods

WeightAcceptance

Single LimbSupporttasks

LimbAdvancement

InitialContact

LoadingRespons

e

MidStance

Terminal Stance

PreSwing

InitialSwing

MidSwing

Terminal Swing

phases

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The gait cycle

M.Whittle

8. terminal swing7. midswing6. initial swing5. preswing

4. terminal stance3. midstance2. load response1. initial contact

filenaam STUDY:

videorapport loopanalysedatum opname:

rechts links

/ /

xxxSYxxx.sty

BewegingsLaboratorium

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Observational GaitAnalysis formRancho Los Amigos Medical Centre

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Edinburgh GAIT Scoring Table

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Error sources in observational kinematic analysis

• Subjective

• estimation error

• out of plane (2D vs. 3D)

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Estimation of joint angles

How well do we perform ?

148 º 24 º

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Estimation of joint angles

How well do we perform ?

148 º 24 º

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Projection error

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Projection error

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Projectionerror (2)

0 10 20 30 40 50 600

20

40

60

80

100

120

140

160

180

angle of observation

obs

erve

d an

gle

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Earliest 3D movement analysisBraun & Fischer 1895

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Multiple 2D projections

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Calibrate the projectioncalibration frame

15 points are known in the real (3D) world

DirectLinear Transformation

Videobased systems: SYBAR, SIMI, PEAK, . . . .

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Automated marker tracking and 3D reconstruction of marker position

Multiple (2+) stroboscopic InfraRedcamera's using reflective markers on the body

Vicon, MotionAnalysis, Elite, Qualysis,. . .

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Automated marker tracking and 3D reconstruction of marker position (2)

Active InfraRed markers 3D camera ('s)

CODAmotion, OptoTrak, . . .

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markerrecording

segmentidentification

Body model anatomicalreference

clinicalconvention

kinematicsmarker-cluster n

kinematicsmarker-cluster 1

kinematics

kinematicsanatomical segm. #1

joint-kinematics

anatomical segm. #2

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3D Kinematics software

Matlabwww.bodymech.nl

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Clinical Feasibility

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Clinical Feasibility

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Clinical Feasibility

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INFORMATION

?

=

KNOWLEDGE

Observational analysis of pathological movement

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Muscle function during movement

Reprinted from: Inman et al. (1981)

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Electro Myo Gram (EMG)

Electrode mounted amplifier

differential lead-off

EMG is the summation of many asynchronous Motor Unit Action Potentials

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Relation EMG and Muscle Force

Raw EMG

Smoothed Rectified EMG @ 2 Hz

Isometric muscle force

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the SYBAR system

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the SYBAR system

display

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casus

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Groundreaction force

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Net joint moment

Moment =

F x r

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Estimated net joint momentversus inverse dynamics

Moment =

F x r

Boccardi et al. (1981)

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What therapeutic intervention is needed ?

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DecisionDisability assessment

General aim of treatment (disability level)no treatment

Decisionfunction analysis

Specific treatment

Evaluation of treatment at two (nested) levels

increased walking speed, decreased PCI

decreased ankle moment at heelstrike

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What therapeutic intervention is needed ?

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Complex Clinical Cases

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Dynamicsexternalmoments andforces

Kinematics- positions- angles- derivatives

Antropometrics:•mass•inertal moments•jointlocations•muscle attachments

Joint andmuscle function

- net moments- estimated

muscle forces

Inverse dynamics model

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Problem statement

Physical examination yields angles

The measure should address muscle length

The reference values are based on normal gait

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Method

• Application of a geometrical musculo-skeletalmodel SIMM (Delp et.al 1995)

• input 1: joint angles during physical examination

• input 2: joint angles during normal gait

• output: muscle length (origo-insertion)

• all lengths are normalized to anatomical position(=100 % )

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Results: m. Rectus Femoris (1)

•Figure 6.2

Figure 6.1

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Results: m. Rectus Femoris (2)

100,0%102,0%104,0%106,0%108,0%110,0%112,0%114,0%116,0%118,0%120,0%

0 12 24 36 48 60 72 84 96 108 120

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Length m. Rectus Femoris during gait

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Results: m. Rectus Femoris (3)

95%97%99%

101%103%105%107%109%111%113%

0 8 16 24 32 40 48 56 64 72 80 88 96 %gait

stance swing

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Discussion

• “Passive” muscle length is not the sole cause to contractures during gait

• Muscle length during movement and EMG should be considered

• Warning: validity of the model• Documentation of examination protocols

(standardisation) using modeling software animations creates awareness of muscle length testing

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Imaging•Clinical question

•Functional analysis

•Muscle-bone model•(invers)

•visualization

•function•structure

•load•(intended) therapeutical intervention

•musle-bone model•(forward)

•movement

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casus

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Models (1)

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Models (1)

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functional load and loading capability of the upper extremity

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Upper extremity

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Upper extremity (2)

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j.harlaar@vumc.nl