G AI T
N O R M AL
Part A (Patton)
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Introduction
Gait measurement
techniques
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Mechanics (Patton)
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Force
Motions
EMG
Other
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RLA vs “traditional”
Phases of gait
Observational Gait
Analysis
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Ground reaction forces
COP
GRFV method
Inverse Dynamics method
Calculating joint power
Muscle Torques (Humphrey)
Specialized Gait (Humphrey)
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(Patton)
“Determinants” of gait
Kinematics
Kinetic Patterns
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Terminology
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Part B
Pediatric
Geriatric
Running
slide#1
Review of Mechanics Terminology
Mechanics:
Interaction of forces, motions, deformations, and flow.
Kinematics:
Movements (position, velocity, acceleration, joint angles, etc.)
Kinetics:
Forces during movements (joint torque, GRF, etc.)
Forward Dynamics:
How forces cause movements. We use dynamics to estimate the
movements that result from forces and moments.
(a=F/m).
Inverse Dynamics:
How movements require forces. We use inverse dynamics to
estimate the forces that cause the motions we measure.
(F=ma).
Most labs use measured forces and measured motions combined to
get a best estimate of joint torque and muscle actions.
(Patton)
slide#2
Mechanics & mechanical
Patterns:
“streamlined research” gives
patterns & deviations
5.1 Center of mass motion
Determinants of Gait
5.2 Kinematics:
Sagittal, Frontal, Transverse, & Other
5.3 Kinetics
GRF’s, COP, “GRF vector method” for
estimating joint moments, inverse
dynamics, sagittal muscle torques
(Patton)
slide#3
0%
10%
Gait Phase Diagram:
20%
30%
PHASES:
40%
50%
60%
70%
80%
90%
100%
Gait cycle is 1 Stride (100%)
Stance (60 to 62%)
Swing (38 to 40%)
SUBPHASES:
Traditional
terminology:
Double
Support
Phase
RLA
terminology:
Loading
Response
Phase
Single Support Phase
Midstance
Double
Support
Phase
Terminal
stance
Deceleration
phase
Acceleration
phase
Preswing
Phase
Initial
Swing
Phase
Midswing
Phase
Terminal
swing
Phase
EVENTS:
Traditional Heel
terminology: strike
Foot Flat
RLA Initial
terminology: con-
Contralateral
Foot off
tact
Midstance
(weight is over
stance leg)
Heel
off
Contralateral
Foot strike
Toe
off
Contralateral
Foot strike
Foot
off
(Jim Patton)
Midswing
(Swing leg is
under the body)
Maximum knee
Flexion
Tibia is
vertical
Heel
strike
Initial
contact
kinesiology gait section, part1 (Patton)
5
kinesiology gait section, part1 (Patton)
6
Center of Mass (CM) motion:
Bipedal tradeoff: mobility vs efficiency
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ADVANTAGES OF BIPEDAL GAIT:
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DISADVANTAGE:
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(Patton)
Bipedal gait frees our hands, elevates our head,
and allows us to move on challenging terrain.
Very hard for our CM to move in a straight line,
which would be the most efficient. (like a wheel.)
Instead, there is an arc-shaped pattern with
lateral sway.
Maintaining a smoother trajectory of the CM plays
a large role in determining HOW we walk
slide#7
Smoothing out CM Excursion
1)
2)
3)
4&5)
6)
Pelvic Rotation
Pelvic List (Lateral Tilt) (Pelvic Drop)
Stance Knee Flexion
Knee, Ankle & Foot Interactions
Lateral Displacement from Hip
Adductors & Genu Valgum
See Saunders (1953), Inman et. al, (1981). Modified slightly from original.
(Patton)
slide#8
PELVIC ROTATION
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n
n
(Patton)
Pelvis moves
forward with swing
limb
Trails behind with
the following limb
Flattens the Arc of
CM motion by
increasing the
effective leg-length
at these times
slide#9
PELVIC LIST
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Pelvis dips down
on swing side
during swing
Lowers CM and
flattens arc
Recently
Recently
disputed
disputedto
tobe
be
not
nottrue
true
(Patton)
slide#10
STANCE KNEE FLEXION
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n
n
(Patton)
Shortens the leg
during stance
Flexion at the
beginning and
end of stance
smoothes the
abrupt changes
in CM
Flattens the arc
Recently disputed to be not true:
Gard, S. A. (1996). "The influence of stance-phase knee flexion on the vertical displacement
of the trunk during normal walking." Journal of Biomechanics 29(10): 1387-91.
slide#11
KNEE, ANKLE & FOOT INTERACTIONS
n
Heel-strike: Knee is
extended and ankle is
dorsiflexed to lengthen the
leg
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Loading response (HS
to FF): knee flexes, ankle
plantarflexes, and foot
pronates
n
Midstance to terminal
stance (FF to HO): Knee
extends, ankle dorsiflexes
n
(Patton)
Preswing (HO to TO):
ankle plantarflexes to
lengthen the leg
Heel
Strike
Loading
Response
Terminal Preswing
Stance
Recently disputed to be not true:
Kerrigan DC, Della Croce U, Marciello M, Riley PO. A refined
view of the determinants of gait: significance of heel rise.
Arch Phys Med Rehabil 2000;81:1077-80.
slide#12
GENU VALGUM & HIP ADDUCTION
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(Patton)
Valgus at the knee
permits a narrower
walking base, and
thus a smaller
lateral shift
Tibia about vertical
Femur articulates
adducts to shift CM
in the frontal plane,
toward the line of
progression
slide#13
Averages 1 inch anterior to S2 on the
midline
l about 55% of body height up from the
floor.
l During gait, the CM still waves up and
down and side to side in a sinusoidal
trajectory that has about a 2 inch
amplitude
l
(Patton)
slide#14
Gait is Variable
539 strides of a “normal” subject
kinesiology gait section, part1 (Patton)
15
Sagittal, lower extremity kinematics
dominate gait
l Gross motions and muscle groups
l Sometimes the only thing measured
l VARIABILITY MUST BE CONSIDERED
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(Patton)
People are variable
Measurement techniques are variable
slide#16
40
Sagittal: Hip
30
Avg+std
avg
Avg-std
degrees
20
10
0
0
20
40
60
80
100
-10
-20
(Patton)
% gait cycle
slide#17
70
Sagittal: Knee
60
50
Avg+std
avg
Avg-std
degrees
40
30
20
10
0
-10
(Patton)
0
20
40
60
% gait cycle
80
100
slide#18
15
Sagittal: Ankle
10
degrees
5
0
-5
-10
-15
0
20
40
60
80
100
Avg+std
avg
Avg-std
-20
-25
(Patton)
% gait cycle
slide#19
Loading Response Phase
(Heel Strike to Foot Flat)
(see also pg. 30 of Observational Gait Analysis)
HIP: 25° flexion
l KNEE: 0° ® 15° flexion (Lowers CM)
l ANKLE: 0° ® 10° plantar flexion
l
“1st
“1strocker:”
rocker:”
Calcaneus
Calcaneus
(Patton)
slide#20
Midstance Phase
(Foot Flat to “midstance event”)
HIP: 25° flexion ® 0°
l KNEE: 15° flexion ® 0° flexion
l ANKLE: 10° plantar flexion ® 5° dorsi
flexion
l
“2nd
“2ndrocker:”
rocker:”
ankle
ankle
(Patton)
slide#21
Terminal Stance Phase
(“midstance event” to Heel Off)
HIP: 0° flexion ® 20° extension
l KNEE: 0°
l ANKLE: 5° dorsi flexion ® 10° dorsi
flexion
l
Continue
Continue“2nd
“2ndrocker:”
rocker:”ankle
ankle
At
Atend
endof
ofterminal
terminalstance,
stance,
Begin
“3rd
rocker:”
Begin “3rd rocker:”MTP
MTP
(Patton)
slide#22
Preswing Phase
(Heel Off to Toe Off)
HIP: 20° extension ® 0°
l KNEE: 0° ® 40° flexion
l ANKLE: 10° dorsi flexion ® 20° plantar
flexion
l
“3rd
“3rdrocker:”
rocker:”
MTP
MTP
(Patton)
slide#23
Swing Phase (Toe Off to Heel Strike)
HIP: 0° ® 30° flexion
l KNEE: 40° flexion ® 60° flexion ® 0°
l ANKLE: 20° plantar flexion ® 0°
l
Note:
Note:
RLA
RLA divides
divides swing
swing into
into 33
sections,
sections, where
where we
we will
will not
not
cover
cover itit in
in this
this amount
amount of
of detail.
detail.
(Patton)
slide#24
Other motions
Pelvic tilt
n
5° forward in early stance, then tilts 5° backward
in late stance, then tilts
5°vvforward
again by late
bble
a
i
r
e
a
l
a
d
i
r
n
a
a
RROOM
M 55°° and
swing
Arms
n
Swing opposite to the legs (out of phase).
Smoothes the CM trajectory.
MTP
n
(Patton)
0° ® 30° ® 60° dorsiflexion
slide#25
Hip & Pelvis
Pelvic Obliquity (Pelvic List)
Near midstance, the CM is high.
The swing side of the pelvis drops
down during swing to lower the CM.
Hip AB-Adduction
Hip adducts in early stance about 5°,
abducts in late stance about 5°, and
returns to neutral in swing.
(Patton)
slide#26
Subtalar
In early stance, eversion
(pronation) unlocks the
midtarsal joint, allowing shock
absorption.
Initial
Contact
Loading
Response
Terminal
Stance
In late stance, inversion
(supination) locks the midtarsal
joint, allowing a rigid forefoot
lever for heel off.
(Not quite frontal)
(Patton)
slide#27
Hip, trunk & lower limb
Pelvic Rotation
n
the swing leg side of the pelvis rotates 10° with the
swing leg.
Trunk Rotation
n
n
Lower trunk (below T7/T8 ) rotates with the pelvis.
Upper Trunk rotates opposite to this (180° out of
phase)
Femoral/Tibial Rotation
n
(Patton)
internal rotation until foot flat, then externally
rotates until toe off, then internally rotates through
swing.
slide#28
Talo-crural & Talo-calcaneal joints act as a
torque converter
Pronation at heel-strike is
converted to internal tibial
(and subsequently
femoral) rotation.
External rotation of the
femur between midstance
event and toe-off is
converted into supination
of the foot.
(Patton)
slide#29
Ground Reaction Forces (GRF)
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The equal-and-opposite
force the floor exerts on
the body during stance
Best measured with a
force plate
Forces are typically
resolved into:
n
n
n
(Patton)
Vertical Compression (z)
Anterior-Posterior Shear (y)
Medial-Lateral Shear (x)
slide#30
Vertical GRF
140
% body weight
120
l
100
l
80
l
60
Avg+std
avg
Avg-std
40
20
l
l
“M” shaped curve
There can be a
spike at heel
contact
Hump during
loading response
Valley at
midstance
Hump in preswing
0
0
(Patton)
20
40
60
% gait cycle
80
100
slide#31
Anterior-Posterior Shear Force
30
% body weight
25
20
15
Avg+std
avg
Avg-std
l
10
l
5
0
-5 0
20
40
60
l
-10
-15
-20
(Patton)
l
% gait cycle
Friction is
required to walk
normally
Often an anterior
spike at heel
contact
Braking hump in
loading
response
80
100
Acceleration
hump in
preswing
response
slide#32
Medial-Lateral Shear Force
3
Avg+std
avg
Avg-std
% body weight
2.5
2
1.5
1
l
0.5
l
0
-0.5 0
20
40
60
-1
Highly
variable
CM is
usually
medial to
the
so
80 foot,
100
odds are it
is a lateral
force
-1.5
(Patton)
% gait cycle
slide#33
Kinetics: Center Of Pressure (COP)
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l
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(Patton)
Represents the centroid of
foot forces on the floor
This is an idealization,
because pressures are
distributed all over
It is important, because we
want to know where the
GRF is applied to the body
When measured by a force
plate, it is more correctly
called the point of
application of the GRF
COP
GRF
slide#34
l
Plotting the COP as it
moves under the
foot:
n
n
(Patton)
Normal Path: Center of the
calcaneus or slightly lateral,
curving laterally and then
medial (pronation) and ending
between the 1st and second
toes
Variable: Normal individuals
can have many COP
trajectories, just by changing
their gait style.
slide#35
kinesiology gait section, part1 (Patton)
36
kinesiology gait section, part1 (Patton)
37
(see website for these)
(Patton)
slide#38
The “GRF Vector Method”
Estimating external joint torques
LR
MSt
flex
flex
plantar
Midstance
event
TSt
zero
exten
flex
zero
exten
dorsi
dorsi
TThhis is Exter
is is Externnaal torque
l torque
((to
torrqquuee ddeem
a
manndd))
vvss
IInnternal torq
ternal torquuee
((m
u
mussccle
le to
torrqquuee))
PSw
exten
flex
dorsi
flex
dorsi
NOTE: This method is dynamically inaccurate & can give WRONG results.
(Patton)
slide#39
GRF Vector Method:
Why this is NOT correct
(Patton)
l
Dynamics are neglected
l
The faster the gait, the more error
l
Accuracy is fair for distal joints (ankle
and sometimes knee)
l
Neck example: if we use this to
estimate the neck moment, we end up
with an outrageous value.
l
GRF Vector Method says all moments
during swing are zero, which is not true
l
(see Winter, 1990)
l
What is the correct way?
INVERSE DYNAMICS
slide#40
Muscle torques:
What are the muscles doing in gait?
l
An external (GRF) force :
l
l
l
l
l
Inverse dynamics:
l
l
(Patton)
can cause motion OR,
can be countered by gravity OR,
it can be resisted by muscle OR,
any combination of the above
tell us the net effect of the muscles
Example:
“The muscles crossing the ankle are generating a
NET torque of 70 Newton*meters at heel rise”
slide#41
Cause & Effect
motorneurons
muscle
tensions
torques
accelerations
converging
converging
& mixing
mixing
MOTION
Dynamic
Dynamic
equations
equations
Why can’t we get the actual muscle tensions?
It is difficult to estimate the actual muscle forces from torques, because many
muscles can make the same torque (due to “converging” of muscles to torques)
(Patton)
slide#42
gives
givesthe
theparts
parts
Torques caused by motions
(IQ)
Kinematics
(positions, velocities, and
accelerations)
Inverse
Dynamics
LEFTOVERS: Net torques
caused by muscles and other
passive structures such as
ligaments, skin, etc. (RJT)
GRF & COP
IDA :
GRFVM :
&
&
IQ = SML + RJT
SML = -RJT
kinesiology gait section, part1 (Patton)
(Patton)
Torques caused by gravity
(ML)
43
slide#43
Disadvantages of Inverse
Dynamics
No information on co-contraction
l No information on elastic storage
l No information on passive structures
(ligament, skin, clothing)
l No information on what role bi-articular
muscles are playing
l
(Patton)
slide#44
SAGITTAL muscle torques:
ANKLE
the fo
the following
are alllowingsslides
re alllmusclelides
tora
muscl
q
torquuees ob
e
e
using s obttaain
inedd
v
singin
e
dynaum
r
nverssee
dynamics. iC
these ics. Coom
pa
thesetorque mparree
those torques to
thoseestima s to
from testimatted
from the GRF ed
methohe GRF
Obsermethoddin
Observationa in
Anvaaltyisonal lGGaaiti
t
Analysis
is
`
`
3 Plantarflexion (+)
2
moment
Nm/KG 1
0
-1
(Patton)
Dorsiflexion (-)
slide#45
SAGITTAL muscle torques:
KNEE
2
Extension (+)
moment 1
Nm/KG
0
-1
(Patton)
Flexion (-)
slide#46
SAGITTAL muscle torques:
HIP
2
Extension (+)
moment 1
Nm/KG
0
-1
(Patton)
Flexion (-)
slide#47
Simply multiply torque times velocity
l UNITS (for angular power):
(Newton*meters/sec) = watts
l Positive: prime mover is concentric
l Negative: prime mover is eccentric
l Does not show co-contraction
l 3D is problematic
Hip
Joint
Power
(Watts/Kg)
(F/E)
(F/E)
Ankle
(D/P)
Concentric (+)
Eccentric ((-)
% Gait Cycle
(Patton)
Knee
% Gait Cycle
% Gait Cycle
slide#48
l
Books:
n
n
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n
n
n
n
n
n
n
n
n
n
n
Gage, James R. Gait analysis in cerebral palsy. Clinics in
developmental medicine; no.121. London: Mac Keith, 1991.
Inman, VT, Ralston, HJ, Todd, F. (1981) , Human Walking,
Baltimore: Williams and Wilkins
Inman & Saunders, Human Walking (2nd Edition).
Perry, Jacquelin. Gait analysis: normal and pathological
function. Thorofare, N.J: SLACK, 1992.
Vaughan, CL. Gait analysis laboratory an interactive book &
software package. [kit]. Champaign, Ill: Human Kinetics
Publishers, 1992.
Vaughan C.L., B.L. Davis, and J.C. O'Connor, "Dynamics of
Human Gait", 1st edition, Human Kinetics Publishers, 1992
Vaughan, Christopher L. Biomechanics of human gait: an
annotated bibliography. 2nd ed. Champaign, Ill.: Human
Kinetics Publishers, 1987.
Weber, Wilhelm Eduard. Mechanics of the human walking
apparatus. Berlin: Springer-Verlag, 1991.
Whittle, Michael. Gait analysis: an introduction. Oxford:
Butterworth-Heinemann, 1991.
Winter, David A. The biomechanics and motor control of
human gait: normal, elderly and pathological. 2nd ed.
Waterloo, Ont.: University of Waterloo Press, 1991.
Winter, David A. A.B.C. (anatomy, biomechanics, control)
of balance during standing and walking. Waterloo, Ont.:
Waterloo Biomechanics, 1995.
Gait: an anthology. [United States]: American Physical
Therapy Association, 1981.
Winters and Woo (eds), Multiple Muscle Systems, Springer
Verlag, 1990.
Craik and Oatis (eds), Gait analysis: Theory and
application. Mosby-Yearbook, St. Luis, 1995.
l
Local Labs/Clinical Facilities:
l
Gait Journals:
n
n
n
n
n
n
n
l
n
n
n
n
l
NU/Rehab. Institute (RIC): Dudley Childress, Scott Delp.
Chicago Children’s Hospital Clinical Gait Lab
U. Of Illinois at Chicago and Rush Presbyterian St. Luke’s
VA/Hine’s Hospital
Gait & Posture
Journal of Biomechanics
Human Movement Science
Key Journal Articles:
Ounpuu, S., (1994) The biomechanics of walking and
running Clinics in Sports Medicine, 13(4) 843-863.
Saunders, J. B., V. T. Inman, H. D. Eberhardt (1953) The
major determinants in normal and pathological gait. The
Journal of Bone and Joint Surgery. 35-A:543-558.
Winter, D. A. (1984) Kinematic and Kinetic patterns in
Human Gait: Variability and Compensating Effects. Human
Movement Science. 3:51-76.
Kirtley C, Whittle MW & Jefferson RJ (1985) Influence of
Walking Speed on Gait Parameters Journal of Biomedical
Engineering 7(4): 282-8.
Web/Internet:
n
n
n
n
(Patton)
t or
no e f on
re bl al
u’ s i r i e
Yo on ate lid
sp m s s
r e h e th i
t
Where to get more info
Clinical Gait Analysis Web Page and Listserver:
http://www.curtin.edu.au/curtin/dept/physio/pt/staff/kirtley
/cga/
Biomechanics Listserver:
http://www.kin.ucalgary.ca/isb/biomch-l.html
http://www.linder.com/muybridge.html
http://165.124.30.88/jim/kinesiology_gait
slide#49