www.footscan.com footscan ® course 2006 welcome. footscan ® course 2006 all rights reserved. no...
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www.footscan.com
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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“What do we measure?”
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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“What do we measure?”
Force
Pressure
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“What do we measure?”
100 N
1 cm² 4 cm²
Pressure
100 N / cm ² 25 N / cm ²
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“What do we measure?”
“Total contact time off the foot”:
= STANCE PHASE SWING PHASE
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“with a high frequency”:
150 Hz – 300 Hz – 500 Hz
“What do we measure?”
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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)
Basics of the anatomical terminology
Sideway view of the left foot
medial
lateral
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Basics of the anatomical terminology
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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Basics of the anatomical terminology
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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Basics of the anatomical terminology
Ligaments:
Knee and ankle joint:
medial and lateral ligaments for stability
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Basics of the anatomical terminology
Ligaments:
Plantar aponeuroses
From calcaneus till the base of the toes
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Basics of the anatomical terminology
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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Basics of the anatomical terminology
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m. extensor digitorum longus
Basics of the anatomical terminology
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m. peroneus longus and brevis
Basics of the anatomical terminology
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Joints/Bones and their possible movements:
Hip: flexion & extension
Femur: interne & extension rotation
Basics of the anatomical terminology
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Joints/Bones and their possible movements:
Knee: flexion & extension
Tibia: interne & external rotation
Basics of the anatomical terminology
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Joints/Bones and their possible movements:
Ankle: only plantar & dorsal flexion
Subtalar Joint: pronation & supination
Basics of the anatomical terminology
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Joints/Bones and their possible movements:
Line of Chopart: pronation & supination
Line of Lisfranc: pronation & supination
Metatarsophalangal: plantar & dorsal flexion
Basics of the anatomical terminology
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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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Analyze dynamic measurement
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At each frame we see: Center of pressure
Analyze dynamic measurement
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Analyze dynamic measurement
At each frame we see:
actual direction of the talus
max adduction position
max abduction position
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Analyze dynamic measurement
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
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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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Analysis of a dynamic measurement
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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Analysis of a dynamic measurement
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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Analysis of a dynamic measurement
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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Analysis of a dynamic measurement
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Most used functions
Analysis of a dynamic measurement
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Analysis of a dynamic measurement
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Analysis of a dynamic measurement
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Male, 53 y
Functional foot type
Prof. R Cavanagh
Analysis of a dynamic measurement
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Impulse division over the entire contact area
Analysis of a dynamic measurement
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Analysis of a dynamic measurement
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Analysis of a dynamic measurement
www.footscan.comTine Willems, Gait & Posture
Analysis of a dynamic measurement
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Analysis of a dynamic measurement
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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 curves
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footscan® balance curves
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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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footscan® balance curves
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Comparing two measurements
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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
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Case studies
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• Leg length discrepancy
Case studies
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Case studies
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Case studies
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• Shin problems
Case studies
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Case studies
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Case studies
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• Achilles tendon problems
Case studies
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Case studies
• Rear foot pronation
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Case studies
• Practice examples of pronation
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Case studies
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Case studies
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• Hallux Valgus
RSscan INTERNATIONAL
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Case studies
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Case studies
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Case studies
Overloading M2 & M3in propulsion and twist
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Case studies
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Case studies
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Case studies
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Case studies
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Case studies
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Case studies
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RSscan INTERNATIONAL
Sn BL Walking
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RSscan INTERNATIONAL
Sn BL Run
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RSscan INTERNATIONAL
Sn Tr shoeL Run
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RSscan INTERNATIONAL
Sn Tr shoe Run
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RSscan INTERNATIONAL
Sn Comp shoe Run
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RSscan INTERNATIONAL
Sn Comp shoe Run
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Case studies
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Case studies