www.footscan.com footscan ® course 2006 welcome. footscan ® course 2006 all rights reserved. no...

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footscan® Course 2006

Welcome

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footscan® Course 2006

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or

otherwise, without the prior permission of RSscan International, [email protected]

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Goals

• Optimal measuring• Understand and use all features of the footscan®

7 gait software• Get more information out of footscan®

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Overview of the day

Part 1: - What do we measure?- Anatomy of the foot- Procedures and analyzing static measurements- Procedures dynamic measurements

Tea-break

Part 2: - Biomechanics of gait- Analyzing dynamic measurements (1)

Lunch

Part 3: - Analyzing dynamic measurements (2)

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“What is it about?”

footscan® =

a dynamic plantar pressure measuring system with a high frequency

Volunteers?

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“What do we measure?”

footscan® measures local pressure during the total contact time of the foot with a high frequency

Locally:

Because footscan® consist of a lot of small sensors with a density of almost three sensors per square centimetre

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Highest pressure

Lowest pressure

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“What do we measure?”“pressure”:

footscan ® consist out of small sensors which we call pressure sensors

Pressure is not the same as force!

Pressure is Force (N) divided by a certain surface (cm2).

Pressure = N / cm2

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Force

Pressure

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100 N

1 cm² 4 cm²

Pressure

100 N / cm ² 25 N / cm ²

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“Total contact time off the foot”:

= STANCE PHASE SWING PHASE

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“with a high frequency”:

150 Hz – 300 Hz – 500 Hz


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Conclusion

Local pressure or total force

During the complete stance phase

With a high frequency

Off the foot Complex structure

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Basics of the anatomical terminology

Building blocks of the body:

• Bones

• Ligaments

• Muscles

Coupling the bones and directing joint movement

Move bones or stabilize them by using the ligaments

Building blocks of the body

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Basics of the anatomical terminologyBones:

femur

patella

fibula

tibia

femur Tibia en fibula

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Calcaneus

Talus

Cuboid

NavicularCuneiforms

Metatarsals

1 - 5

23

4

5

1

Hallux

Toes 2 – 4 (phalanges)


Sideway view of the left foot

medial

lateral

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Calcaneus Talus

Cuboid Navicular

CuneiformsMetatarsals

1 - 5

Hallux

Toes 2 - 4

Top view of the foot

MedialLateral

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Basics of the anatomical terminologyJoints:

Ankle joint

Subtalar joint

Transversal tarsal joint = Chopart’s line

Tarsometatarsal joint = Lisfranc’s line

MeTatarso-Phanlangeal joints (MTP)

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Medial

Lateral

Rearfoot Midfoot Forefoot

HL

HM T1M1

M5

M4M3M2

Most common terms in the footscan® software:

T2 – T5

MF

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Basics of the anatomical terminologyUsed zone in the footscan® software:

HLHM

T1

M1

M5M4

M3M2

T2 – T5

MF

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Ligaments:

Knee and ankle joint:

medial and lateral ligaments for stability

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Ligaments:

Plantar aponeuroses

From calcaneus till the base of the toes

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Muscles:

Initiate motion

Limit extreme motions

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Basics of the anatomical terminologyMovements of the right foot:

Plantar flexion

Dorsal flexion

Pronation:

Eversion

Abduction

Dorsal flexion

Supination:

Inversion

Adduction

Plantar flexion

Valgus position

Varus position

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Basics of the anatomical terminology4 Muscle groups:

P ronation

P lantar flex i

M . Peroneus longus M . Peroneus brev is M . Extensor d ig itorum longus

on M . Triceps surae M . Peroneus longus M . Peroneus brev is M . F lexor hallucis longus M . Tib ia lis poste rior

D orsa l flex ion

S upina ti

M . Tib ia lis an terio rM . Extensor d ig itorum longusM . Extensor ha lluc is longus

onM . Triceps suraeM . Tib ia lis poste riorM . F lexor hallucis longusM . F lexor d ig itorum longusM . Tib ia lis an terio r

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Analysis of a dynamic measurement

J. Deckers & D. Beckers,

Bohn Stafleu Van Loghum

Pronators

Supinators

Dorsal flexors

Plantar flexors

Decelerate

foot

Prepare push off

Stabilisation calcaneus

Heellift

Push off

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m. extensor digitorum longus


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m. peroneus longus and brevis


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Joints/Bones and their possible movements:

Hip: flexion & extension

Femur: interne & extension rotation


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Knee: flexion & extension

Tibia: interne & external rotation


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Ankle: only plantar & dorsal flexion

Subtalar Joint: pronation & supination


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Line of Chopart: pronation & supination

Line of Lisfranc: pronation & supination

Metatarsophalangal: plantar & dorsal flexion


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Static measurement

With this information in the back of our heads we can continue with the first part of the measurements:

The static measurements

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Static measurement

1) Control preferences

2) Recalibrate (1 x per 3 months)

3) Add a patient to the database

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Static measurement

Procedures:

Patient has to stand barefooted on the platform

for a number of seconds

Hands hanging next to the body

Looking straight ahead

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Static measurement

Static measurement = momentary recording

Gives:

- Static maximal pressures

- Deviation of the body weight

(in stance!)

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Static measurement

Normal left-right dividing 50% - 50% Possible causes for differences:

- proprioceptical problems - structural problems, like

a leg length difference - alignment problems with orthotics –

prosthetics Also look for large front-backwards differences

- possible static problemsOr look for diagonal differences

- possible pelvic rotation

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Static measurement

Remark: footscan can only show that there is a difference.

Possible causes must be further verified.

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Static vs Dynamic measurement

Static vs Dynamic measurement

Procedure:

Necessary space:

6 to 10 m total walkway length for walking

12 to 20 m total walkway length for running

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Dynamic measurement

Measuring procedure for a 0.5 m plate

When the foot does not land in the centre of the platform, start from the green or yellow line

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Dynamic measurement

Is this a good measurement?

Control:

Contact time:

Slight difference between left - right

Normal walking measurement: +/- 800 ms

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Dynamic measurementFurther control:

Are the footscan zones and foot axis correct?

The zone of T1 is too large

This will lead to false conclusions

Also does the foot axis not start at the middle of the heel.

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Dynamic measurementCorrect zones:

See the footscan software manual for a detailed explanation

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Dynamic measurement

Control ok? Save measurement

Repeat this procedure several times and then use the best measurement for your analysis.

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pause

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Analyze dynamic measurement

What do we see?

• Unroll left and right footHere we can use the - button so we can look

frame per frame

• Maximal pressure for the left and right foot

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Analyze dynamic measurementVisualizations:

Roll off

3D Synchro Impulse

2D

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Analyze dynamic measurement• Impulse:

0,2 s

6 Ns/cm2

18 Ns/cm2

0,6 s

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At each frame we see: Center of pressure


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At each frame we see:

actual direction of the talus

max adduction position

max abduction position

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How does a measurement go?

First we repeat the necessary biomechanics.

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BiomechanicsCoupled movements (1):

Rotation femur = rotation tibia

A stretched knee has no rotation possibility

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Biomechanics

Coupled movements (2):

Internal tibia rotation

eversion calcaneus pronation subt. joint

External tibia rotation

inversion calcaneus supination subt. joint

Because the ankle joint can only plantar and dorsal flex.

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BiomechanicsCoupled movements (3):

Pronation of the subtalar joint = detaching the tarsals through Chopart’s line

by this detaching the tarsals do not have to follow the rearfoot pronation and enables a correct positioning of the forefoot, so that the longitudinal arch can absorb the shock

Supination of the subtalar joint = lock the tarsals through Chopart’s line

by this locking the foot becomes a rigid lever

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Biomechanics

What does Lisfranc's line?

Nothing if Chopart's line has it's normal function

Else Lisfranc's line will take over Chopart's line function

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Biomechanics

MTP joints : dorsal flexion

Tighten the plantar aponeuroses

Helps creating a rigid lever

http://images.google.nl/imgres?imgurl=http://www.wsiat.on.ca/images/Windlass_mechanism.gif&imgrefurl=http://www.wsiat.on.ca/english/mlo/plantar_screen.htm&h=445&w=389&sz=14&hl=nl&sig2=OcP2hurkTYaZhQ-5_zS-Aw&start=1&tbnid=69mcVVzwRTZtSM:&tbnh=127&tbnw=111&ei=_ynjRL3qN8TSwgGxvsD4DQ&prev=/images%3Fq%3Dwindlass%2Bmechanism%26svnum%3D10%26hl%3Dnl%26lr%3D

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BiomechanicsWhat happens during gait?

Robert Mack, The C.V. Mosby Company, 1980

Internal rotation

External rotation

Pelvis

Internal rotation

External rotation

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This rotation movements explain the heel’s movements.

Because of the coupled movement at Chopart’s line we must seek another explanation for the COP-line of the rest of the foot

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After 15% of the stance phase there is a external rotation of

the femur causing the subtalar joint to supinate

Foot = a rigid lever which transfers weight and helps with

the push off

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Williams & Wilkins, second edition

Further course of the COP line:

- By it’s anatomical positioning M5 comes down first

- Because the body’s centre of mass position shift, it has to remain above the supporting leg. Making it move from medial to lateral and eventually back to the other leg medial: unroll from M5 M1

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Most used functions


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Male, 53 y

Functional foot type

Prof. R Cavanagh


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Impulse division over the entire contact area


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www.footscan.comTine Willems, Gait & Posture


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Lunch

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footscan® balance curves

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footscan® balance curvesLook at the curves the following way:

X axis = total foot contact time

Y axis = ratio of the movements

Look at the structures which are being used in the calculation

Look at the colours which match with the left or right foot, which are the loaded measurements

Look at the (a) symmetry of both feet

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footscan® balance curvesHeel rotation

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footscan® balance curvesForefoot balance

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footscan® balance curvesMedial forefoot balance

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footscan® balance curvesHallux stifness

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footscan® balance curvesMeta loading

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footscan® balance curvesFoot balance

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Comparing two measurements

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Average over several measurements

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Case studies

• Case studies– To further explain the possibilities of footscan– Sports, orthopaedics or podiatrists– Practical examples

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Case studies

• Knee problems

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Case studies

Sagittal knee movements

J. Deckers & D. Beckers, Bohn Stafleu Van Loghum