Gait Analysis: Techniques and Recognition of Abnormal Gait Fabian E' Pollo, Ph'D'

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Gait Analysis Techniques and Recognition
ofAbnormal GaitFabian E. Pollo, Ph.D.

• April 30, 2007

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Gait analysis in modern terms implies that some
type of quantification will take place.
Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Gait analysis involves the measurement of
1. Temporal / Spatial velocity, cadence, step
length, etc. 2. Kinematics - the movement
of the body in space without any reference
to forces. 3. Kinetics - the forces involved in
producing these movements. 4. Dynamic
Electromyography - the study of muscular
activity patterns during walking.
Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Temporal-Spatial Parameters

• Stop watch and marks on the floor
• Gait Pressure Mat

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Gait Pressure Mat
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Kinematics can be recorded using a variety of
systems and methodologies
Passive Marker Systems use reflective markers and
multiple cameras (typically 6 to 8 cameras
simultaneously). The cameras send out infra red
light signals and detect the reflection from the
markers placed on the body. Based on the
reflected signals from at least 2 cameras -
triangulation of the marker in space is possible.
Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Kinematics can be recorded using a variety of
systems and methodologies
Active Marker Systems are similar to the passive
marker system but use "active" markers. The
markers are triggered to illuminate. This signal
is used to triangulate the location of the
marker. The advantage is that individual markers
work at predefined frequencies and therefore,
have their own "identity".
Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Kinematics can be recorded using a variety of
systems and methodologies
Electromagnetic Systems track the position (X, Y,
and Z Cartesian coordinates) and orientation
(azimuth, elevation, and roll) of small sensors
attached to various segments of the body as they
move through space.
Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Baylor Motion Sports Performance Center

• Vicon Motion Analysis System
• Twelve MX-40 Cameras
• 4 Megapixel Resolution
• 5 Hz 2,000 Hz
• Passive Marker System
• Near Infra-Red Ring LEDs
• Camera/Computer

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Camera Positioning (Think Volume)
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Calibration L-Frame
L- Frame designates lab origin and orientation
(Global Coordinate System)
Z
X
Y
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Calibration Wand
Wand defines camera positions in relation to
each other in 3D space and corrects for any lens
distortion
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Various Markers Sets and Gait Models dependent on
application
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Direct Linear Transformation
Camera 1
Camera 2
Identified Markers 3D Image
3D Image
DLT
Camera 3
Camera 12
Take all 12 Raw Video Camera Views
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Kinematics
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Kinetics
Force Platform
The reaction force produced by the ground is
called the Ground Reaction Force (GRF), which is
basically the reaction to the force the body
exerts on the ground.
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Kinetics
Use Inverse Dynamics to compute Joint Forces,
Joint Torques (Moments) and Joint Power.
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Electromyography
0.051mm, insulated, hooked wires
25 Gauge Needle
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Processing
Raw EMG Signal
Rectified EMG Signal
Enveloped EMG Signal
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Recognition of Abnormal Gait

• Question is not whether a gait pattern is
  abnormal what is primary cause.
• Requires formal gait analysis
• Many primary causes are fairly easy to diagnose
  (i.e. bunions and peroneal nerve dysfunction)
• Many secondary causes that are not so clear
  (chronic ligament tears and osteoarthritis)

Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Recognition of Abnormal Gait
Examples

• Mild Cerebral Palsy
• Traumatic Brain Injury
• Medial Compartment Osteoarthritis

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Cerebral Palsy

• 9 year old girl with hemiplegia
• Equinovarus of her right foot
• (inverted hindfoot and plantarflexed)
• Caused by overpull of the tibialis posterior
  and/or anterior tibialis Tendons

Gait Analysis Techniques and Recognition of
Abnormal Gait
April 30, 2007
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Surgical Options
Split anterior tibialis and transfer tendon to
cuboid.
Split posterior tibial tendon and transferred
laterally to peroneus brevis tendon
Gait Analysis Techniques and Recognition of
Abnormal Gait
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Use of Gait Analysis

• Determine if the anterior tibialis and/or
  posterior tibialis was contributing to her
  deformity.
• Document her movement pattern for comparison
  after surgery.

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Traumatic Brain Injury

• 45 year male suffered TBI in car accident in
  1983
• Having Left Knee Pain
• Gait Evaluation

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Knee Osteoarthritis

• 51 year old women with medial compartment OA
  of left knee
• Evaluation for OA unloader brace prior to
  possible High Tibial Osteotomy

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Knee Osteoarthritis

• Knee OA results from local mechanical factors
  within the context of systemic susceptibility
• Hip-knee-ankle alignment significantly influences
  load distribution at the knee and disease
  progression
• Medial compartment more often affected

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Knee Loading

• Vertical GRF

• Muscular Forces

• Reaction force from external moment

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Knee Osteoarthritis

• Unloader Bracing attempts to reduce that
  Varus load.

Gait Analysis Techniques and Recognition of
Abnormal Gait
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Benefits of Gait Analysis

• Aids in surgical planning
• Assessing the efficacy of surgical intervention
• Bracing issues and medication efficacy can be
  addressed using gait analysis techniques
• Evaluation of the rate of deterioration in
  progressive disorders that affect gait can also
  aid in understanding a patient's abilities and
  directing care
• Quantification for clinical and research

Gait Analysis Techniques and Recognition of
Abnormal Gait
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THANK YOU

• April 30, 2007