Swing Phase Control and Stance Phase Control
The gait cycle has a stance and a swing phase for each limb. There is a normal time relationship of 60% stance phase and 40% swing phase that each limb cycles through with each step. This 60 : 40 ratio is affected by gait deviations. To achieve a sustainable velocity is critical for a normal gait appearance. Thus, the stance to swing ratios serve as a good clinical tool to measure success.
Orthoses are now judged similar to prosthetic knee joints. How well they control the lower limb in swing phase and stance phase of the gait cycle determine their success. The new designs have made the biggest impact on stance phase control capabilities. The stance phase of walking is where all the potential destructive forces of load bearing takes place. *As weight is borne on the load bearing column, the limb and/or orthosis must generate enough force to counteract the forces tending to buckle the limb and to enable a fluid progression. These moments are normally counteracted by muscle action. In the absence of normal muscle function, the orthoses must provide the needed functions or disabilities may result in an aberration from normal gait. The combination of triplanar and balance control, better floor reaction designs, and energy response capability all enhance the stance phase control of the new designs.
The swing phase aspect of the gait cycle is the easiest to orthotically control. It requires minimal effort to support the extremity in the swing phase of the gait cycle. The new designs are enhancing the swing phase, as well as, capitalizing on the advent of energy response designs. The energy released by the orthosis at terminal stance propels the leg up and forward. The velocity of the swinging limb is increased which helps the body to move forward and re-establish the normal swing to stance phase ratios. This allows the energy from one step to be transferred to the next step, thus taking advantage of inertia and momentum.