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

2. 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

3. 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

4. Temporal-Spatial Parameters
Stop watch and marks on the floor
Gait Pressure Mat
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

5. Gait Pressure Mat
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

6. 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

7. 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

8. 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

9. 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
Force Platforms
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

10. Camera Positioning (Think Volume)
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

11. Calibration: L-Frame
L- Frame – designates lab origin and orientation (Global Coordinate System) Z X Y
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

12. 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
April 30, 2007

13. Various Markers Sets and Gait Models dependent on application
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

14. 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
Virtual Hip Joint Centers
DLTs convert digitized 2-D coordinate locations to 3-D space coordinate locations
In this process, the known 2-D coordinates, as well as the digitized coordinates of
the calibration points, are used to solve a set of simultaneous linear equations which
relate one set of coordinates to the other.
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

15. Kinematics Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

16. 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
April 30, 2007

17. Kinetics
Use Inverse Dynamics to compute Joint Forces, Joint Torques (Moments) and Joint Power.
Power is Energy / time, the rate at which energy is created (positive power) or absorbed (negative power)
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

18. 0.051mm, insulated, hooked wires
Electromyography
0.051mm, insulated, hooked wires
25 Gauge Needle
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

19. Processing Gait Analysis: Techniques and Recognition of Abnormal Gait
Raw EMG Signal
Rectified EMG Signal
Enveloped EMG Signal
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

20. 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

21. Recognition of Abnormal Gait
Examples
Mild Cerebral Palsy
Traumatic Brain Injury
Medial Compartment Osteoarthritis
Once the brain damage has occurred it does not change. A consequence of the brain damage however is that it affects how the muscles and bones develop. Many children therefore experience difficulties with walking which may change as they grow.
Each child will be affected differently. Walking patterns can be complex depending on the location, type and severity of the brain damage and on the growth of bones and muscles. Some children will also learn tricks ("compensatory mechanisms") to allow them walk more easily. Each child will develop a unique walking pattern related to their individual condition.
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

22. 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

23. 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
April 30, 2007

24. 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

25. 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

26. 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

27. 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

28. Knee Loading Vertical GRF Muscular Forces
Reaction force from external moment
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

29. Knee Osteoarthritis
Unloader Bracing attempts to reduce that “Varus” load.
Power is Energy / time, the rate at which energy is created (positive power) or absorbed (negative power)
Gait Analysis: Techniques and Recognition of Abnormal Gait
April 30, 2007

30. 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
April 30, 2007

31. April 30, 2007
THANK YOU