Gait Analysis: Techniques and Recognition of Abnormal Gait Fabian E. Pollo, Ph.D. April 30, 2007

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

April 30, 2007

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Gait analysis in modern terms implies that some type of quantification will take place.


April 30, 2007

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 involves the measurement of:


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Temporal-Spatial Parameters

1. Stop watch and marks on the floor

2. Gait Pressure Mat

Gait Pressure Mat


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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.


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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".


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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.

Z

Y X


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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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Camera Positioning (Think Volume)


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X Y

Z

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


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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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Various Markers Sets and

Gait Models dependent on

application


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Direct Linear Transformation

Camera 1 Camera 2

Camera 3…………Camera 12

3D Image

DLTTake all 12 Raw Video Camera Views

Identified Markers3D Image

Virtual Hip Joint Centers


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Kinematics


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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 the ground.

Kinetics


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Use Inverse Dynamics to compute Joint Forces, Joint Torques (Moments) and Joint Power.

Kinetics


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Electromyography

25 Gauge Needle0.051mm, insulated, hooked wires


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Raw EMG Signal

Rectified EMG Signal

Enveloped EMG Signal

Processing


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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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1. Mild Cerebral Palsy

2. Traumatic Brain Injury

3. Medial Compartment Osteoarthritis

Examples

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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Surgical Options

Split anterior tibialis and transfertendon to cuboid.

Split posterior tibial tendon and transferred laterally to peroneus brevis tendon


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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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Traumatic Brain Injury

• 45 year male suffered TBI in car accident in 1983

• Having Left Knee Pain

• Gait Evaluation

http://www.wreckedexotics.com/newphotos/bad/bad749.shtml


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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


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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


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• Vertical GRF

• Muscular Forces

• Reaction force from external moment

Knee Loading


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Knee Osteoarthritis

• Unloader Bracing attempts to reduce that “Varus” load.


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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

THANK YOUApril 30, 2007

Documents

Gait Analysis: Techniques and Recognition of Abnormal Gait Fabian E. Pollo, Ph.D. April 30, 2007