The overall goal of this method is to simplify the objective measurement of gait patterns for daily rehabilitation through the use of three dimensional motion analysis. This method can diagnose the progress of gait rehabilitation, especially for gait disorders caused by disease such as stroke, spinal cord injury or hip fracture. The main advantage of this technique is that this method is connection friendly.
It uses a simple measurement procedure and it has intuitive data presentation. Demonstrating the procedure will be Junya Yamada, a Physical Therapist from our hospital. He is the chief technician of our gait analysis laboratory.
Before preparing a subject, be sure that the imaging equipment has been been calibrated according to the manufacturer's instructions. This protocol utilizes a simplified video-based motion analysis system. It is said to take samples at 60 hertz and is not as costly as standard 3D GA systems.
The subject should wear comfortable skin-tight leggings that permit easy attachment of the colored sensors near the skin. The markers, detected by the imaging equipment, are 30 millimeters in diameter, and needs specific placement. First, place markers on both acromion.
Then, place markers on the lateral malleoli of the ankles. Next, place markers on the fifth metatarsal heads of the feet. Next place markers on the knees, specifically along the midline of the anterior posterior diameter of each lateral epicondyle of the femur.
Then place markers on both hips between the anterior superior iliac spine and the greater trochanter, about one third of the way from the greater trochanter. Then place the last required markers on the iliac crest, along the vertical line of the iliac crest casting through the hips. For measurements, have the subject walk along the treadmill while the cameras record the movement of the markers.
Start the treadmill at a conservative speed, about 70 percent of the anticipated walking speed of the subject. Then gradually increase the speed, asking the subject to report when the treadmill feels like it is moving at their normal walking speed. Now, take a 20-second recording with the camera for measurements.
Only one 22nd recording is needed for each treadmill speed tested. If several gait speeds are tested, let the subject rest for a minute between tests. For the analysis, first calculate the time distance parameters.
The foot contact and foot lifting data are automatically calculated by the system based on toe and ankle marker trajectories. To avoid errors in the step detection, have two experienced physical therapists verify the accuracy of the timing. And repair any errors in the automated data collection.
The calculation of various parameters can be done within the gait analysis software or in a spreadsheet. Next, create a logistics overview picture, or a LOP. LOPs show the marker-joint trajectories on the major joints.
This data described the holistic gait pattern of the subject. To begin the LOP calculation, first determine the virtual center of gravity. Give each body segment a set of standardized values, construct line segments, and use the center of the segments as the virtual center of gravity.
Next calculate movement in the horizontal, sagittal, and coronal planes. At each marker, extract the raw data for the three components for each gait cycle. Next adjust the data to the virtual center of gravity on the horizontal plane to cancel out the horizontal displacement of the subject as they walk on the treadmill.
Then normalize these values by the gait cycle and calculate the average value across the gait cycle. Now, draw the LOP using the gait analysis software or by constructing a scatterplot that covers the motion range of all the markers in a spreadsheet. Use the trajectories of the coordinates of 10 markers and the virtual center of gravity.
The described procedure was used to assess a stroke patient with a hemiparetic gait and a healthy control. In the LOP of a stroke patient's complete gait pattern, typical gait patterns such as circumduction, hip elevation, and trunk lateral movement can all be observed. This gait pattern was then analyzed using a radar chart.
Standardized scores of circumduction and hip elevation were high, indicating that those movements in the stroke patient were much greater than the standard of healthy subjects. Finally, toe clearance strategies were assessed. In a healthy subject, toe clearance is usually achieved by limb shortening, whereas the stroke patient achieves toe clearance mainly by compensatory movements such as pelvic obliquity, and vaulting.
Since its development, this technique has helped the patients in the field of rehabilitation medicine to explore the mechanisms of gait disorders and therapeutic interventions.
