title: Postural stability index is a more valid measure of stability than equilibrium score.
abstract: Researchers, therapists, and physicians often use equilibrium score (ES) from the Sensory Organization Test, a key test in the NeuroCom EquiTest System (a dynamic posturography system) to assess stability. ES reflects the overall coordination of the visual, proprioceptive, and vestibular systems for maintaining standing posture. In our earlier article, we proposed a new measure of anterior-posterior (A-P) postural stability called the Postural Stability Index (PSI), which accounts for more biomechanical aspects than ES. This article showed that PSI provides a clinically important adjunct to ES. In the present article, we show that PSI can provide an acceptable index even if a person falls during the trial, whereas ES assigns a zero score for any fall. We also show that PSI decreases as ankle stiffness increases, which is intuitive, while ES exhibits the opposite behavior. Ankle stiffness is generally recognized as an indicator of postural stability. These results suggest that PSI is a more valid measure of A-P stability than ES.
authors.affiliation: War-Related Illness and Injury Study Center, Department of Veterans Affairs Medical Center, East Orange, NJ, USA.
authors.forename: Hans
authors.initials: H
authors.lastname: Chaudhry
authors.forename: Thomas
authors.initials: T
authors.lastname: Findley
authors.forename: Karen S
authors.initials: KS
authors.lastname: Quigley
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Ji
authors.forename: Miriam
authors.initials: M
authors.lastname: Maney
authors.forename: Tiffany
authors.initials: T
authors.lastname: Sims
authors.forename: Bruce
authors.initials: B
authors.lastname: Bukiet
authors.forename: Richard
authors.initials: R
authors.lastname: Foulds
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology; D001259:Ataxia / Q000175:diagnosis* / Q000503:physiopathology*; D004548:Elasticity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011187:Posture / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D019415:Torque; D014728:Veterans