The 3-dimensional (3-D) analysis performed at the Center for Gait and Movement Analysis is comprised of several different tests, including kinematics, kinetics and stride characteristics. From these tests, we can create a skeletal avatar unique to your child. This 3-D understanding of your child will enable our team to more accurately assess abnormalities in your child’s movement.
A child with the motion-capture marker stickers
Computer models of the skeletal avatar
Your therapist will first ask your child to walk a line the length of the room several times in their most natural form of walking – barefoot and if possible, without orthotics or assistive devices. Once this has been videotaped, your therapist will begin to add back in any devices they typically rely upon and videotape this as well. These movements are recorded by several different cameras from several different angles.
What is motion capture?
Motion Capture (MoCap) records any type of human movement using special cameras and computer programs. This is the same technology used to make some of your child’s favorite animated movie characters and video games!
3-D motion kinematics: A picture of walking
Our 3-D motion kinematics creates a 3-dimensional picture of how your child moves and walks. Small markers, similar to the electrodes used in the previous step, are used to help the cameras and computer software develop 3-dimensional joint motion data. These markers are different in that they are small reflective balls, similar to ping pong balls that attach to your child’s skin with a small circular sticker. Markers are placed on specific bony landmarks of the pelvis and both lower extremities, and in some cases, the trunk and upper extremities.
Special cameras are located throughout the room and track these markers on your child as she walks across the room, capturing the data needed to create a 3-dimensional picture. This test is done as naturally as possible, barefoot with no assistive devices. As with the electrodes, these markers can cause some mild irritation when they are removed, but many patients say they just feel like removing a very small bandage or sticker.
A patient walks for the motion-capture cameras at the Center for Gait and Movement Analysis
Your child’s data are then compared to graphs of normal gait to identify abnormal or unusual patterns of motion, as well as the magnitude of her variation from norm.
3-D motion kinetics: Measuring the force of walking
In addition to the markers, we also measure the force your child gives off when walking. Motion kinetics describes the physical forces that produce joint motions during walking. Specifically, the foot/floor contact forces during the walking trial are measured directly by custom force platforms imbedded in the floor.
Stride characteristics: Measuring how your child walks
“Stride” is defined as a cycle from the initial contact of one foot with the ground to the next time the same foot makes contact. During this part of the analysis, we’ll measure your child’s stride characteristics, which include the average walking velocity, cadence, stride length, gait cycle time, double limb support time and single limb support time.
Our staff will then compare your child’s stride characteristics to that of typically developing children to identify how your child’s needs may be different.
Step 4: 3-D motion analysis and stride characteristics