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

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

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

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

Gait Pressure Mat 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

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

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

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

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

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 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

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

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

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

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

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

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

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

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 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

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

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

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

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

April 30, 2007 THANK YOU