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Gait Analysis:

Techniques and

Recognition of

Abnormal Gait

Fabian E. Pollo, Ph.D.

April 30, 2007

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

April 30, 2007

Gait analysis in

modern termsimplies that

some type ofquantification

will take place.

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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1. Temporal / Spatial velocity, cadence, steplength, 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 ofmuscular activity patterns during walking.

Gait analysis involves the measurement of:

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Gait Analysis: Techniques and

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Temporal-Spatial Parameters

1. Stop watch and marks

on the floor

2. Gait Pressure Mat

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Gait Pressure Mat

Gait Analysis: Techniques and

Recognition of Abnormal Gait

April 30, 2007

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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 themarker in space is possible.

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Gait Analysis: Techniques and

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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. Thissignal 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".

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Gait Analysis: Techniques and

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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.

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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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

Baylor Motion & Sports Performance Center

Force Platforms

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Camera Positioning (Think Volume)

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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X Y

Z

L- Frame designates lab origin and orientation (Global Coordinate System)

Calibration: L-Frame

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Wand defines camera positions in relation to each other in 3D space and

corrects for any lens distortion

Calibration: Wand

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Various Markers Sets and

Gait Models dependent on

application

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Direct Linear Transformation

Camera 1 Camera 2

Camera 3Camera 12

3D Image

DLTTake all

12 Raw Video

Camera Views

Identified Markers3D Image

Virtual Hip Joint Centers

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Kinematics

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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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 theground.

Kinetics

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Use Inverse Dynamics

to compute Joint Forces,

Joint Torques

(Moments) and JointPower.

Kinetics

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Electromyography

25 Gauge Needle0.051mm, insulated, hooked wires

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Raw EMG Signal

Rectified EMG Signal

Enveloped EMG Signal

Processing

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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)

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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1. Mild Cerebral Palsy

2. Traumatic Brain Injury

3. Medial Compartment Osteoarthritis

Examples

Recognition of Abnormal Gait

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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

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Surgical Options

Split anterior tibialis and transfertendon to cuboid.

Split posterior tibial tendon and

transferred laterally to peroneus

brevis tendon

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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.

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Traumatic Brain Injury

45 year male suffered TBI in caraccident in 1983

Having Left Knee Pain

Gait Evaluation

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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 unloaderbrace prior to possible High

Tibial Osteotomy

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Knee Osteoarthritis

Knee OA results from local

mechanical factors within thecontext of systemic susceptibility

Hip-knee-ankle alignment

significantly influencesload distribution at the knee and

disease progression

Medial compartment more oftenaffected

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Vertical GRF

Muscular Forces

Reaction force fromexternal moment

Knee Loading

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Gait Analysis: Techniques and

Recognition of Abnormal Gait

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Knee Osteoarthritis

Unloader Bracing attempts to

reduce that Varus load.

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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 inprogressive disorders that affect gait can also

aid in understanding a patient's abilities and

directing care

Quantification for clinical and research

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THANK YOUApril 30, 2007