Gait Analysis Flashcards
What is gait?
Gait is the pattern of movement of the limbs of animals, during locomotion over solid substrate
Gait is selected based on…
Speed, terrain, the need to maneuver, and energetic efficiency
what are 4 forms of human gait
Walking
Running
Sprinting
Crawling
Normal human gait..
Repeats a basic sequence of limb motions that serve to progress the body along a desired path while maintaining weight bearing stability, conserving energy and absorbing shock of floor impact
Repeats a basic sequence of limb motions that serve to progress the body along a desired path while maintaining ….
weight bearing stability, conserving energy and absorbing shock of floor impact
What are the 2 main reasons to measure walking gait?
To find out how we walk and to use walking as a baseline measure to understand differences between: healthy and unhealthy populations, ages, genders, and races
We use walking as a baseline measure to understand differences between….
healthy and unhealthy populations, ages, genders, and races
Gait analysis involves the measurement of what 3 things?
Kinematics
Kinetics
EMG
What is EMG
Electromyography- a techniques for evaluating and recording the electrical activity produced by skeletal muscles
What are 7 of the methodologies used to record kinematics
Passive marker systems Active marker systems Electromagnetic systems Electrical goniometers Accelerometers Gyroscopes Magnetometers
What are passive marker systems
Use reflective markers and multiple cameras
Multiple cameras are necessary to…. (in kinematics recording)
to ensure that we can digitize each marker and determine its 3 dimensional location
From 3D digitized markers we can…
derive the joint kinematics
What are active marker systems
Similar to passive marker systems but use “active markers”. The markers are triggered to illuminate. Each marker works at a predetermined frequency and therefore have their own identity
What are electromagnetic systems
A way of recording kinematics. Track the position (X, Y, and Z Cartesian coordinates) and orientation of small sensors
What are electrical goniometers
- An electrical device for measuring joint angles
-
What are some benefits of goniometers
Simple to use and are relatively inexpensive compared to motion capture systems
What are some tools used to record kinetics
Pressure mats and insoles
Force plates
What type of info due forceplates imbedded in treadmills provide
the most detailed information about contact kinetics
What does combining kinematic and kinetic data do?
Allows us to use inverse dynamics to calculate joint forces, torques and muscle force
Phases of Gait can be based on…
important changes and transitions in kinetic and kinematic information
Stance phase is ___% of the gait cycle
62%
Swing phase is ___% of the gait cycle
38%
What comprises the gait cycle
62% stance phase, 38% swing phase, with two periods of double stance that occupy 25% of the gait cycle
The two period of double stance occupy ___% of the gait cycle
25%
What is initial contact
instantaneous point when leading foot touches the ground
What is loading response
Body weight transferred onto stance limb
What is midstance
When you are vaulting over limb, centre of mass is moving forward over limb
Contralateral foot leaves the ground and body weight travels along length of foot ntil aligned over the forefoot
What is terminal stance
Begins with heel rise, ends when opposite foot contacts the ground
What is preswing
- It begins with opposite foot contact, ends with ipsilateral toe off
- Stance limb unloaded and body weight transferred onto opposite limb
What is terminal contact
Instant when foot leaves the ground
What is initial swing
It begins the moment the foots leaves the ground and continues until maximum knee flexion occurs
What is midswing
begins following maximum knee flexion and ends when the tibia is in a vertical position
What is terminal swing
The tibia passes beyond perpendicular, and the knee fully extends in preparation for heel contact
why is the wing phase broken up purely kinematic
because we have no force measurement
What does timing of peak muscle activity tell us
about muscle function during gait
What is the muscle activation of the glutes during gait
Hip extension during loading response
What is the muscle activation of the quads during gait
Knee extension during loading response
What is the muscle activation of the calves during gait
ankle platarflexion during heel rise in terminal stance
why is the iliopsoad not active during gait
because it is relying on momentum
Why are glutes active at the end of gait cycle
to slow it down
Why is tibialis anterior active at the end of the cycle
to dorsiflex foot so it doesn’t hit the ground
When are the iliopsoas the most active in the gait cycle
Initial swing
When are the hamstrings most active
loading response and terminal swing
when are the triceps surae most active
terminal stance
What are the iliopsoas doing during the gait cycle
hip flexion during pre and initial swing
What are the hamstrings doings during the gait cycle
Hip extension to decelerate limb during terminal swing
What are the tib ant doing during the gait cycle
ankle dorsiflexion during swing phase and loading to maintain foot position
Hip changes from ___ to ___ just before terminal stance
extension to flexion
Knee changes from ___ to ___ during swing
max flexion to max extension
The ankle changes from ___ to____ just after terminal stance
plantar to dorsi
What is the joint moment determined by
- The muscle moment
2. The amplitude and line of action of the ground reaction force
What does joint moment tell us
gives us an understanding of what is happening in terms of the torque
The flex/ext moment caused by the ground reaction for is related to…
whether the line of action passes in front or behind the joint
What is centre of pressure
the instantaneous point of application of the ground reaction force
What does measuring foot centre of pressure movement during walking tell us
about the point of application of the GRF vector and how we use our feet while walking
What 3 functional tasks that walking can be broken down in to
- Weight acceptance
- Single-limb support
- Limb advancement
What is weight acceptance
the demand for immediate transfer of body weight onto the limb as soon as it contact the ground
What does weight acceptance require
- Initial limb stability
- Shock absorption
- momentum of progression preservation
What is single limb support
The total body weight is exclusively supported on the stance limb
What does single limb support require
forward progression while maintaining stability
What is limb advancement
the stand limb leaves the ground and advances forward to posture itself in preparation for next initial contact
What is the inverted pendulum model
a mechanical analogy of how we walk
During a single limb support the body (CoG) vaults over the extended limb with minimal energy expenditure
What is the redirection of the CofG during double limb support
over the extended limb and the inverted pendulum continues on the other side
When is the major energy expenditure during double limb support
during the redirection portion
During walking a major goal is…
Being energy efficient
How is being energy efficient accomplished during walking
by minimizing unnecessary movement of the CofG
What are the 6 determinants of gait
- Pelvic rotation
- Pelvic obliquity
- Knee flexion in stance phase
- Ankle mechanism
- Foot mechanism
- Lateral displacement of body
During gait the pelvis rotates around the ___ axis
vertical
What does pelvis rotation allow for during gait
greater steps
less bob
Pelvic rotation about the vertical axis reduces…
the angle of hip flexion and extension, which in turn reduces the vertical movement of the hip
if the pelvic did not rotate…
the whole of the stride length would come from hip flexion and extension
What is pelvic obliquity
when you have pelvis or hip drop - reduces the bouncing up and down of CofG.
The vertical movement of the trunk is less that that of the hip, due to pelvic tilt about an anteroposterior axis
Why do we do knee flexion in stance phase (gait determinants)
Without knee flexion, you vault higher and therefore have greater bob of centre of mass
What is ankle mechanism
The initial contact to the ground. Body is at higher position then if foot was flat. This acts to extend limb maintaining CoM at a higher height
what is the foot mechanism
at toe off body is at higher heigh (CoM doesnt drop as low) minimizes movement of centre of mass
What is the lateral displacement of the body
stance width - if feet are really far apart when trying to walk, CoM moves back and forth a lot (left and right).
What are some common simple measures that can provide sufficient information to compare the gait of individuals
- Changes in swing stance ratio
- left/right asymmetry
what will be the distribution of stance to swing phase in a patient with left hip avascular necrosis
58% stance, 42% swing in painful limb
and
69% stance, 31% swing in sound limb
what will be the distribution of stance to swing phase in a patient with osteoarthritis in left hip
60% stance, 40% swing in painful limb
and
80% stance, 20% swing in sound limb
What is lateral trunk bending
Bending the trunk towards the side of the supporting limb during the stance phase
When is lateral trunk bending most commonly seen
- Coxalgic gait
- Trendelenburn gait
What is coxalgic gait
pelvis is parallel to ground but bent over
What is trendelenburg gait
Have lean and hip drop. Pelvis is NOT parallel to ground. Happens as a result of abductor on side of lean
What is the purpose of lateral trunk bending
to reduce the forces in the abductor muscles and hip joint during single leg stance
What are 4 common causes of lateral trunk bending
- Painful hip - osteoarthritis and rheumatoid arthritis
- Hip abductor weakness
- leg length discrepancy
- Abnormal hip joint
What is anterior trunk bending
The subject flexes his or her trunk forwards early in the stance phase
What is the purpose of anterior trunk bending
to move the CoG of the body forwards, moving the line of force to pass in front of the axis of the knee, producing an extension moment
Where is the line of action of the GRF normally found in early stance
passes behind the knee axis and generates a knee flexor moment
GRF going behind the knee causes…
the knee to flex
How do you stop knee from flexing when GRF is going behind the knee
you need to actively contract quads to resist flexion and extend knee
When GRF is in front of knee it causes the knee to…
extend or to stay extended
Do you use quads when the GRF is in front of the knee
no
When does the GRF go in front of the knee
When you have quad weakness or other problem with knee where you dont want extra forces across the knee
What is posterior trunk bending
the subject extends his or her trunk backwards early in the stance phase
Normally, where does the line of action of the GRF pass in early stance
in front of the hip axis
Which the line of action of the GRF passing in front of the hip axis what motion does it generate
a hip flexor moment
What does posterior trunk bending do to the line of action of the GRF
brings it behind the hip joint
What occurs if the line of action of the GRF is behind the axis of the hip joint?
creates a hip extensor moment
which four gait abnormalities are closely related
Circumduction
Hip hiking
steppage
vaulting
Why are circumduction, hip hiking, steppage, and vaulting all closely related
they all compensate to overcome the same problem - a functional discrepancy in leg length
What is circumduction
A swing phase modification - avoiding ground contact by the swinging leg by swinging it outward
What is hip hiking
swing phase modification, where the pelvis is lifted on the side of the swinging leg
What is steppage
Swing phase modification - an exaggerated knee and hip flexion, to lift the foot higher than usual for increased ground clearance
What is vaulting
stance phase modification - ground clearance is increased if the subject goes up on the toes of the stance phase leg
