biodex 945-480 Installation & Operation Manual page 7

CONTENTS
Benefits Specific to the Biodex Unweighing System
Oscillation of Center of Gravity (COG) - Normal oscillation for the center of gravity during gait
is approximately 2" (5cm). This is easily achieved with the dynamic suspension of the Biodex
Unweighing System. By allowing oscillation, the patient is able to maintain a smooth gait pat-
tern (Hoppenfeld). When a static support system is used and the center of gravity is raised, the
system is not able to maintain a constant unweighing. During toe off, the patient may actually
be full weight bearing, which may cause undesired firing patterns of the musculature, resulting
in poor training effects.
Knee Flexion Throughout Gait Cycle - In order to provide for shock absorption and mechanical
efficiency, the knee must flex at various points during the gait cycle. During toe off the COG will
rise, the knee flexes to approximately 40º to counterbalance this effect. A static unweighing sys-
tem will not allow this to occur and will therefore promote poor mechanics during gait training.
Poor mechanics can lead to increased stress placed on compensatory joints and muscles and also
inappropriate motor control patterns. Knee flexion also allows ground reaction forces (GRF) to
occur. GRFs are important for motor firing patterns associated with motor pattern and central
pattern generators. The dynamic environment of the Biodex Unweighing System allows for
development and utilization of these GRF in the re-training of gait.
Single Point Design - A single point of suspension allows proper shifts of the COG and proper
pelvic rotation during gait. By providing natural shifts of the COG strengthening and coordina-
tion can be rehabilitated to their original state. Unweighing Systems that provide a two point
support design do not allow for the necessary shift of the COG over vital points necessary for
gait. A two point design suspends the patient in a static "hanging" position, not allowing lateral
pelvic tilts and pelvic rotation necessary for efficient gait mechanics. Lateral pelvic tilt of
approximately 1" allows the body weight to be centered over the hip, this allows the non-weight
bearing leg to swing through. The pelvis then rotates forward with the weight bearing hip act-
ing as a fulcrum allowing forward movement of the non weight bearing limb. The single point
design of the Biodex Unweighing System allows for proper biomechanics of the pelvis and uti-
lization of trunk musculature for stabilization and forward propulsion.
Digital Display of Unweighing Load - The digital display incorporated on the Biodex
Unweighing System provides feedback in regards to the amount of weight being relieved from
the patient. This is beneficial as it allows for consistency between treatments thus providing a
therapeutic environment to improved gait mechanics and neurological patterning.
— 7 — PARTIAL WEIGHT BEARING