It is possible to use a simple video to estimate a person's kinematics. In this analysis, video of the sagital plane of the child walking is analyzed to find the angles of hip and knee flexion. This is graphed vs. position and compared to a normal gait pattern below.
Stills for Gait Analysis
These stills show the aproximate vectors of the HAT (head, arms, torso) in green, the thigh in orange and the shank in red that are used to find the HAT angle, thigh angle and shank angle.
This still shows the shank, thigh and HAT angles. These angles are used to find the knee and hip flexion angles. The equations to find hip and knee flexion angles are as follows.
Knee Flexion Angle = Thigh Angle - Shank Angle
Hip Flexion Angle = Thigh Angle - HAT Angle
The curve of the child's knee flexion angle, shown in red, follows roughly with the curve of the normal gait data, shown in grey. The overall range of the child's knee flexion angle was significantly less than that of normal gait data. The data suggest that because the child is in constant knee flexion throughout the gait cycle, he is in crouch gait while using the walker.
The curve of the child's hip flexion angle, shown in red, follows roughly with the curve of the normal gait data, shown in grey. The hip flexion angle is smaller than normal and exibits periods of extreme hyperextension. There is also a decrease in hip flexion angle early in the gait cycle that does not occur in normal hip flexion data.