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.

Gait Analysis: Techniques and Recognition of Abnormal Gait

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:

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Temporal-Spatial Parameters

1. Stop watch and marks on the floor

2. Gait Pressure Mat

Gait Pressure Mat

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

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

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.

Z

Y X

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

• 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

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Camera Positioning (Think Volume)

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

X Y

Z

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

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Wand – defines camera positions in relation to each other in 3D space and corrects for any lens distortion

Calibration: Wand

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Various Markers Sets and

Gait Models dependent on

application

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Kinematics

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

Kinetics

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Electromyography

25 Gauge Needle0.051mm, insulated, hooked wires

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Raw EMG Signal

Rectified EMG Signal

Enveloped EMG Signal

Processing

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

1. Mild Cerebral Palsy

2. Traumatic Brain Injury

3. Medial Compartment Osteoarthritis

Examples

Recognition of Abnormal Gait

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

Surgical Options

Split anterior tibialis and transfertendon to cuboid.

Split posterior tibial tendon and transferred laterally to peroneus brevis tendon

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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

April 30, 2007

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

April 30, 2007

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

April 30, 2007

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

April 30, 2007

• Vertical GRF

• Muscular Forces

• Reaction force from external moment

Knee Loading

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

Knee Osteoarthritis

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

Gait Analysis: Techniques and Recognition of Abnormal Gait

April 30, 2007

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