Report Parameters - biodex BioSway Operation Manual

8. REPORTS AND DATA
The BioSway offers reports for each of the test modes. These can be used to objectively measure
and record the patient's balance ability. Progress reports that graph overall stability scores from
each test date are also available.
Sample reports for each testing mode are provided later in this chapter.

report parameterS

The following parameters appear on various reports:
Stability Index
Stability index is the average position from center. The Stability index does not indicate how
much the patient swayed. For this we use the standard deviation of the Stability index. This
value we have called the Sway Index.
Sway Index
The Sway Index is really the Standard deviation of the Sway Angle. The higher the Sway Index
the more unsteady the person was during the test.
(Refer to Appendix C for additional information)
The Stability Index is represented in the following formats:
1. The Overall Stability Index takes into account COG displacement in the following directions
2. Anterior/Posterior (A/P)-Sagital Plane
3. Medial/Lateral (M/L)-Frontal Plane
overall Stability Index
The following equation is used to calculate the Overall Stability Index.
(DI) 2 =
2
√ ∑ (0 – X) + ∑ (0 – Y)
# of samples
anterior/posterior (a/p)
The Anterior/Posterior Stability Index represents platform displacement in a sagital plane. A
high score in this direction may indicate poor neuromuscular control of:
1. The quadriceps and/or hamstring muscles
2. The anterior/posterior compartment muscles of the lower leg.
The following equation is used to calculate the Anterior/Posterior Stability Index:
medial/lateral (m/l)
The Medial/Lateral Stability Index represents platform displacement in the frontal plane. A high
score in this direction may be indicative of:
1. Bilaterally- Poor neuromuscular control of the abductor and adductor muscles of the lower
leg.
2. Unilaterally — Poor neuromuscular control of the inversion or eversion muscles of the lower
leg, especially following an ankle sprain.
The following equation is used to calculate the Medial/Lateral Stability Index:
2
DI =
2
DIy = √ ∑ (0 – Y)
# of samples
DIx = √ ∑ (0 – X)
2
# of samples
— 8-1 —
(DI) 2
REPORTS AND DATA